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A hybrid method to determine efficiency curve of HPGe detectors.
Ozben, Cenap S; Emirhan, Erhan M
A method was developed for determining the efficiency calibration curve of HPGe detectors between 26 and 1770 keV. A simple simulation based on the attenuation of gamma-rays in pure germanium was used together with efficiency calibrations performed for three detector-source distances: 5, 12 and 30 cm. The simple simulation model required an energy dependent term with three parameters and these parameters were determined from the fit of the simulated data to the measured efficiency of the detector. The efficiency response of the detector determined this way was then tested with other certified sources to verify the validity of the method. PMID:19297177
Gamma-ray efficiency of a HPGe detector as a function of energy and geometry.
Challan, Mohsen B
The concept of double points detector model approach (DPDM) is developed as a procedure to find the full energy peak efficiency of the coaxial 120 cm(3) closed hyperpure germanium (HPGe) detectors. Usually in the experimental nuclear physics work, which involves using HPGe detector for gamma-ray spectrometry, the full energy peak efficiency function must represent adequately the HPGe detector response. In the current work the gamma-ray energy in the range from 60 keV to 1332 keV and gamma-ray intensity changes by changing source to detector distance from 10mm to 800 mm. The detector was characterized using a number of point-like standard sources. The calculated efficiencies obtained by (DPDM) are in good agreement with experimental data. PMID:24007787
A software for simulation of efficiency of HPGe detectors
NASA Astrophysics Data System (ADS)
Khiem, L. H.; Trong, T. D.
Computer software named GE_EFF for calculation of detection efficiency of High Purity Ge detectors recently developed by us is presented. A Monte-Carlo method has been used for simulation. The software has been written in Visual Basic language. The calculated efficiencies for our detectors are in agreement with the measured values using a standard ?-ray sources. The software has been used at our laboratory of Institute of Physics for gamma radiation measurements.
Analytical approach for radioactivity correlation of disc sources with HPGe detector efficiency.
Challan, Mohsen B; El-Taher, A
The HPGe detector efficiency is measured as a function of source to detector separation using disc sources of (131)I with diameter ranging from 10 to 400mm. Detector efficiencies are characterized using single photon point-like standard sources at different distances; the calculated efficiencies for disc sources were analyzed by utilizing the double point detector model (DPDM) and the efficiency transfer method. The developed approach provided satisfactory results. The axial variation and radial dependence for disc sources efficiency determination in gamma-ray spectrometry were described with both gamma ray standard sources and measured samples as their extended sources. PMID:24365876
A software package using a mesh-grid method for simulating HPGe detector efficiencies
Gritzo, Russell E [Los Alamos National Laboratory; Jackman, Kevin R [REMOTE SENSING LAB; Biegalski, Steven R [UT AUSTIN
Traditional ways of determining the absolute full-energy peak efficiencies of high-purity germanium (HPGe) detectors are often time consuming, cost prohibitive, or not feasible. A software package, KMESS (Kevin's Mesh Efficiency Simulator Software), was developed to assist in predicting these efficiencies. It uses a semiempirical mesh-grid method and works for arbitrary source shapes and counting geometries. The model assumes that any gamma-ray source shape can be treated as a large enough collection of point sources. The code is readily adaptable, has a web-based graphical front-end. and could easily be coupled to a 3D scanner. As will be shown. this software can estimate absolute full-energy peak efficiencies with good accuracy in reasonable computation times. It has applications to the field of gamma-ray spectroscopy because it is a quick and accurate way to assist in performing quantitative analyses using HPGe detectors.
Evaluation of ANGLE(R), a code for calculating HPGe detector efficiencies
Homan, Victoria M [Los Alamos National Laboratory
This paper evaluates the ANGLE(reg sign) software package, an advanced efficiency calibration software for high purity germanium detectors that is distributed by ORTEC(reg sign). ANGLE(reg sign) uses a semi-empirical approach, by way of the efficiency transfer method, based on the calculated effective solid angle. This approach would have an advantage over the traditional relative and stochastic methods by decreasing the chances for systematic errors and reducing sensitivity to uncertainties in detector parameters. For experimental confirmation, a closed-end coaxial HPGe detector was used with sample geometries frequently encountered at the Los Alamos National Laboratory. The results obtained were sufficient for detector-source configurations which included intercepting layers of plexiglass and carbon graphite, but somewhat insufficient for bare source configurations.
A new model calculation of the peak efficiency for HPGe detectors used in assays of radioactive waste drums.
Stanga, D; Radu, D; Sima, O
In this paper we present a new semi-empirical model calculation of the peak efficiency for unshielded HPGe detectors based on the virtual point detector and the attenuation factor concepts. The validity of the model calculation was checked by comparison with Monte Carlo efficiency values and experimental efficiencies determined for a HPGe detector type GEM 25P4 using a calibration drum. The discrepancy between experimental and calculated efficiencies is smaller than 10% in the energy range 122-1408 keV. PMID:19945290
The determination of the efficiency of a Compton suppressed HPGe detector using Monte Carlo simulations.
McNamara, A L; Heijnis, H; Fierro, D; Reinhard, M I
A Compton suppressed high-purity germanium (HPGe) detector is well suited to the analysis of low levels of radioactivity in environmental samples. The difference in geometry, density and composition of environmental calibration standards (e.g. soil) can contribute to excessive experimental uncertainty to the measured efficiency curve. Furthermore multiple detectors, like those used in a Compton suppressed system, can add complexities to the calibration process. Monte Carlo simulations can be a powerful complement in calibrating these types of detector systems, provided enough physical information on the system is known. A full detector model using the Geant4 simulation toolkit is presented and the system is modelled in both the suppressed and unsuppressed mode of operation. The full energy peak efficiencies of radionuclides from a standard source sample is calculated and compared to experimental measurements. The experimental results agree relatively well with the simulated values (within ?5�-�20%). The simulations show that coincidence losses in the Compton suppression system can cause radionuclide specific effects on the detector efficiency, especially in the Compton suppressed mode of the detector. Additionally since low energy photons are more sensitive to small inaccuracies in the computational detector model than high energy photons, large discrepancies may occur at energies lower than ?100�keV. PMID:22304994
Application of the Monte Carlo efficiency transfer method to an HPGe detector with the purpose of environmental samples measurement.
Morera-G�mez, Yasser; Cartas-Aguila, H�ctor A; Alonso-Hern�ndez, Carlos M; Bernal-Castillo, Jose L; Guill�n-Arruebarrena, Aniel
Monte Carlo efficiency transfer method was used to determine the full energy peak efficiency of a coaxial n-type HPGe detector. The efficiencies calibration curves for three Certificate Reference Materials were determined by efficiency transfer using a (152)Eu reference source. The efficiency values obtained after efficiency transfer were used to calculate the activity concentration of the radionuclides detected in the three materials, which were measured in a low-background gamma spectrometry system. Reported and calculated activity concentration show a good agreement with mean deviations of 5%, which is satisfactory for environmental samples measurement. PMID:25544663
Close-geometry efficiency calibration of p-type HPGe detectors with a Cs-134 point source.
DeFelice, P; Fazio, A; Vidmar, T; Korun, M
When close-geometry detector calibration is required in gamma-ray spectrometry, single-line emitters are usually used in order to avoid true coincidence summing effects. We managed to overcome this limitation by developing a method for the determination of the efficiency of p-type HPGe detectors in close-geometry with a calibrated Cs-134 point source. No separate determination of coincidence summing correction factors is required and a single measurement furnishes the full-energy-peak efficiencies in the 475-1365 keV energy range. PMID:16549352
Performance assessment by Monte Carlo simulations of a prospective assembly of up to three HPGe detectors designed for superior detection efficiency and sensitivity.
Jutier, Christophe; Douysset, Guilhem
The present work reports on the results of Monte Carlo simulations performed with MCNP on an assembly of two HPGe detectors facing each other regarding detector efficiencies. Report is also made when a third detector is added to the previous configuration from below. Moreover cross talk between detectors is investigated and found of limited impact. The choice for an actual detector goes to the three detector configuration for accommodating most geometries while cost and engineering constrains remain acceptable. PMID:22440238
Efficiency transfer in the calibration of a coaxial p-type HpGe detector using the Monte Carlo method.
Vargas, M Jurado; D�az, N Cornejo; S�nchez, D P�rez
Monte Carlo simulation was applied to the efficiency transfer exercise described in the EUROMET428 project (Appl. Radiat. Isot. 55 (2001) 493), evaluating the peak efficiencies in the energy range 60-2000 keV for a typical coaxial p-type HpGe detector and several types of source configuration: point sources located at various distances from the detector and a cylindrical box containing three matrices. The efficiency values were derived in two ways: (a) by direct calculation taking into account the physical dimensions of the detector provided by the supplier, and (b) by means of relative computation (efficiency transfer) taking also into consideration the known efficiency values for a reference point source. As expected, some significant discrepancies between the calculated and experimental values were found when a direct computation was made using the data provided by the supplier. On the contrary, the results for the peak efficiency derived by relative calculation by means of an efficiency transfer were in good agreement with the experimental values. The deviations found with this last procedure were generally below 5% for all the geometries considered, which is entirely satisfactory for the purposes of routine measurements. PMID:12798381
Characterization of HPGe detectors using Computed Tomography
NASA Astrophysics Data System (ADS)
Hedman, A.; Bahar Gogani, J.; Granstr�m, M.; Johansson, L.; Andersson, J. S.; Rameb�ck, H.
Computed Tomography (CT) high-resolution imaging have been used to investigate if there is a significant change in the crystal-to-window distance, i.e. the air gap thickness, in a small n-type detector cooled to 77 K, and in a medium sized p-type HPGe detector when cooled to 100 K. The findings were compared to detector dimension data made available by the manufacturer. The air gap thickness increased by (0.38�0.07) mm for the n-type detector and by (0.40�0.15) mm for the p-type detector when the detectors were cooled to 77 resp. 100 K compared to at room temperature. Monte Carlo calculations indicate that these differences have a significant impact on the efficiency in close geometries (<5 cm). In the energy range of 40-700 keV with a source placed directly on endcap, the change in detector efficiency with temperature is 1.9-2.9% for the n-type detector and 0.3-2.1% for the p-type detector. The measured air gap thickness when cooling the detector was 1.1 mm thicker than manufacturer data for the n-type detector and 0.2 mm thicker for the p-type detector. In the energy range of 40-700 keV and with a source on endcap, this result in a change in detector efficiency of 5.2-7.1% for the n-type detector and 0.2-1.0% for the p-type detector, i.e. the detector efficiency is overestimated using data available by the manufacturer.
New cooling methods for HPGE detectors and associated electronics
D. L. Upp; R. M. Keyser; T. R. Twomey
Summary��Despite the on-going development of room temperature semiconductors for use as gamma-ray detectors, the only material which can provide a solution to the combined requirements of stability, high-energy resolution and high-detection efficiency (at useful energies) is still germanium (HPGe). These properties of HPGe gamma-ray detectors make them invaluable in meeting the demands of the newly emergent and increasingly important applications
Accurate Characterization of the Shape of the HPGe Detector Peak Efficiency Curve for Application in PGNAA
Hawari, Ayman I.
Measurements in prompt gamma neutron activation analysis (PGNAA) typically have errors of the order of {+-}2 to 3%. A method is described that can yield a lower limit on the uncertainty in relative efficiencies applied to PGNAA of about {+-}0.1%.
Experimental and MC determination of HPGe detector efficiency in the 40-2754 keV energy range for measuring point source geometry with the source-to-detector distance of 25 cm.
Dryak, Pavel; Kovar, Petr
A precise model of a 40% relative efficiency p-type HPGe detector was created for photon detection efficiency calculation using the MCNP code. All detector parameters were determined by different experiments. No experimental calibration points were used for the modification of detector parameters. The model was validated by comparing calculated and experimental full energy peak efficiencies in the 40-2754 keV energy range, for point-source geometry with the source-to-detector distance of 25 cm. PMID:16564693
Performance of HPGe Detectors in High Magnetic Fields
A. Sanchez Lorente; P. Achenbach; M. Agnello; T. Bressani; S. Bufalino; B. Cederwall; A. Feliciello; F. Ferro; J. Gerl; F. Iazzi; M. Kavatsyuk; I. Kojouharov; L. Majling; A. Pantaleo; M. Palomba; J. Pochodzalla; G. Raciti; N. Saito; T. R. Saito; H. Schaffner; C. Sfienti; K. Szymanska; P. -E. Tegn�r
A new generation of high-resolution hypernuclear gamma$-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DAPhiNE, the Frascati phi-factory, and at PANDA, the antiproton proton hadron spectrometer at the future FAIR facility. Both, the FINUDA and PANDA spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields B ~ 1 T. The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.
Experience with a factory-calibrated HPGe detector
NASA Astrophysics Data System (ADS)
Bossus, D. A. W.; Swagten, J. J. J. M.; Kleinjans, P. A. M.
For k0-based analysis, an HPGe detector has to be used. This detector has to be absolutely calibrated in a reference position and with a defined geometry so that, using SOLCOI/KAYZERO software package, for example, efficiencies of other positions and sample geometries can be calculated. This reference calibration is a time-consuming procedure during which the detector is not available for analyses. Therefore, DSM Resolve decided to purchase a "factory-calibrated" detector. Efficiency calibrations were ordered for a point-source geometry at a coincidence-free distance from the detector and for two additional distances closer to the detector. After delivery, the factory calibration was checked at DSM Resolve using a limited set of PTB-calibrated reference sources. At the end, we decided nevertheless to perform a standard and full calibration of the detector, because it turned out that the factory-calibrated detector was not accurate enough to be used for quantitative analyses.
Determining HPGe Total Detection Efficiency Using ?�? Coincidence
Erikson, Luke E.; Keillor, Martin E.; Aalseth, Craig E.; Hossbach, Todd W.; Mizouni, Leila K.; Stavenger, Timothy J.; McDonald, Benjamin S.; Lepel, Elwood A.; Greenwood, Lawrence R.; Rutherford, Crystal E.
Abstract Both the peak and total detection efficiencies are generally needed in order to calculate sample activity from a gamma spectroscopic measurement, except in the case of isotope specific calibration. This is particularly true when the sample is in close proximity to the detector and corrections for cascade summing effects are required to avoid significant inaccuracy in the result. These corrections use the total detection efficiency to correct for summing-in and summing-out events, and the extent of the correction depends on both the geometry and the gamma cascade for the isotope in question. Experimentally determining the total efficiency is a labor intensive endeavor requiring multiple measurements with a set of single-gamma-emitting standards. Modeling the total efficiency vs. energy may be less time consuming, but is also likely to produce less confidence in the final result. Pacific Northwest National Laboratory's Radiation Detection and Nuclear Sciences group has constructed a low background 14-crystal HPGe array for sample measurement; in all measurements, samples will be in close proximity to the germanium crystals. This close geometry and the sheer number efficiency calibrations required for the system have led us to investigate methods to simplify the efficiency calibration procedure. One method we are developing uses the Y-Y coincidence plane to isolate Compton scattering event populations, allowing experimental determination of total detection efficiency values from the measurement of a single mixed isotope standard. A description of the analysis and experimental results of this method are presented.
Detection efficiency of Ge(Li) and HPGe detectors for. gamma. -rays up to 10 MeV
Lin, J.; Henry, E.A.; Meyer, R.A.
The relative efficiency up to 9.7 MeV was calibrated for two coaxial detectors, one Ge(Li) and one high purity Ge. The efficiency curves were determined by using a combination of standard radioactive sources and (n,..gamma..) reactions. Based on the result of this work, the general slope of the two detector efficiency curves appears to be similar and in agreement with earlier work reported by McCallum and Coote. When plotted as a semilogarithmic function of energy the efficiency is linear from 2 to 9.7 MeV.
Monte Carlo calculation of the efficiency calibration curve and coincidence-summing corrections in low-level gamma-ray spectrometry using well-type HPGe detectors
Laborie; Le Petit G; Abt; Girard
Well-type high-purity germanium (HPGe) detectors are well suited to the analysis of small amounts of environmental samples, as they can combine both low background and high detection efficiency. A low-background well-type detector is installed in the Modane underground Laboratory. In the well geometry, coincidence-summing effects are high and make the construction of the full energy peak efficiency curve a difficult task with an usual calibration standard, especially in the high energy range. Using the GEANT code and taking into account a detailed description of the detector and the source, efficiency curves have been modelled for several filling heights of the vial. With a special routine taking into account the decay schemes of the radionuclides, corrections for coincidence-summing effects that occur when measuring samples containing 238U, 232Th or 134Cs have been computed. The results are found to be in good agreement with the experimental data. It is shown that triple coincidences effect on counting losses accounts for 7-15% of pair coincidences effect in the case of 604 and 796 keV lines of 134Cs. PMID:10879838
Support of low-level instrument background for HPGe detectors
A. D. Sokolov; A. S. Starostin; V. I. Kuzmenko; A. R. Rozite
The development results for the cryostats with the low-level of instrument background supported by special design, the reduction of mass of the materials surrounding detector and application of the materials with very low content of radiation impurities are presented. The development results for HPGe detector with ultra low-level of instrument background for gamma spectrometer under the GEMMA project for investigation
HPGe detectors long time behaviour in high-resolution ? spectrometry
L. Sajo-Bohus; D. Rosso; A. M. Sajo Castelli; D. R. Napoli; E. Fioretto; R. Menegazzo; H. Barros; C. A. Ur; D. Palacios; J. Liendo
A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA ? spectrometers, as well as environmental measurements have been collected over two decades. In this paper a detailed statistical analysis of this data is given and detector long term behaviour is provided to the scientific community. We include failure, failure mode,
HPGe virtual point detector for radioactive disk sources.
Alfassi, Z B; Lavi, N; Presler, O; Pushkarski, V
Validity of the model of a virtual point detector (implying existence of a point where all interactions virtually occur) was confirmed for measurements of radioactive disk sources with HPGe detectors. The existing correlation of the count rates with the distance between the virtual plain detector and the detector face makes it possible to inter- and extrapolate calibration curves for disk radioactive sources for use at different source-detector face distances. The dependence of the distance between the virtual plane detector and the detector face on the photon energy was studied for sources of various radii. PMID:17000113
Employing Thin HPGe Detectors for Gamma-Ray Imaging
Vetter, K; Mihailescu, L; Ziock, K; Burks, M; Hull, E; Madden, N; Pehl, R
We have evaluated a collimator-less gamma-ray imaging system, which is based on thin layers of double-sided strip HPGe detectors. The position of individual gamma-ray interactions will be deduced by the strip addresses and the Ge layers which fired. Therefore, high bandwidth pulse processing is not required as in thick Ge detectors. While the drawback of such a device is the increased number of electronics channels to be read out and processed, there are several advantages, which are particularly important for remote applications: the operational voltage can be greatly reduced to fully deplete the detector and no high bandwidth signal processing electronics is required to determine positions. Only a charge sensitive preamplifier, a slow pulse shaping amplifier, and a fast discriminator are required on a per channel basis in order to determine photon energy and interaction position in three dimensions. Therefore, the power consumption and circuit board real estate can be minimized. More importantly, since the high bandwidth signal shapes are not used to determine the depth position, lower energy signals can be processed. The processing of these lower energy signals increases the efficiency for the recovery of small angle scattering. Currently, we are studying systems consisting of up to ten 2mm thick Ge layers with 2mm pitch size. The required electronics of the few hundred channels can be integrated to reduce space and power. We envision applications in nuclear non-proliferation and gamma-ray astronomy where ease of operation and low power consumption, and reliability, are crucial.
Employing Thin HPGe Detectors for Gamma-Ray Imaging
Vetter, K; Mihailescu, L; Ziock, K; Burks, M; Hull, E; Madden, N; Pehl, R
We have evaluated a collimator-less gamma-ray imaging system, which is based on thin layers of double-sided strip HPGe detectors. The positions of individual gamma-ray interactions will be deduced by the strip addresses and the Ge layers which fired. Therefore, high bandwidth pulse processing is not required as in thick Ge detectors. While the drawback of such a device is the increased number of electronics channels to be read out and processed, there are several advantages, which are particularly important for remote applications: the operational voltage can be greatly reduced to fully deplete the detector and no high bandwidth signal processing electronics is required to determine positions. Only a charge sensitive preamplifier, a slow pulse shaping amplifier, and a fast discriminator are required on a per channel basis in order to determine photon energy and interaction position in three dimensions. Therefore, the power consumption and circuit board real estate can be minimized. More importantly, since the high bandwidth signal shapes are not used to determine the depth position, lower energy signals can be processed. The processing of these lower energy signals increases the efficiency for the recovery of small angle scattering. Currently, we are studying systems consisting of up to ten 2mm thick Ge layers with 2mm pitch size. The required electronics of the few hundred channels can be integrated to reduce space and power. We envision applications in nuclear non-proliferation and gamma-ray astronomy where ease of operation and low power consumption, and reliability, are crucial.
Employing thin HPGe detectors for gamma-ray imaging
NASA Astrophysics Data System (ADS)
Vetter, K.; Mihailescu, L.; Ziock, K.; Burks, M.; Cork, C.; Fabris, L.; Hull, E.; Madden, N.; Pehl, R.
We have evaluated a collimator-less gamma-ray imaging system, which is based on thin layers of double-sided strip HPGe detectors. The positions of individual gamma-ray interactions will be deduced by the strip addresses and the Ge layers which fired. Therefore, high bandwidth pulse processing is not required as in thick Ge detectors. While the drawback of such a device is the increased number of electronics channels to be read out and processed, there are several advantages, which are particularly important for remote applications: the operational voltage can be greatly reduced to fully deplete the detector and no high bandwidth signal processing electronics is required to determine positions. Only a charge sensitive preamplifier, a slow pulse shaping amplifier, and a fast discriminator are required on a per channel basis in order to determine photon energy and interaction position in three dimensions. Therefore, the power consumption and circuit board real estate can be minimized. More importantly, since the high bandwidth signal shapes are not used to determine the depth position, lower energy signals can be processed. The processing of these lower energy signals increases the efficiency for the recovery of small angle scattering. Currently, we are studying systems consisting of up to ten 2mm thick Ge layers with 2mm pitch size. The required electronics of the few hundred channels can be integrated to reduce space and power. We envision applications in nuclear non-proliferation and gamma-ray astronomy where ease of operation and low power consumption, and reliability, are crucial.
Performance of CdTe, HPGe and NaI(Tl) detectors for radioactivity measurements
A. Perez-Andujar; L. Pibida
The characteristics and performances of the NIST High-Purity Germanium (HPGe), Sodium Iodide (NaI(Tl)) and Cadmium Telluride (CdTe) gamma-ray detectors were studied. The efficiencies, the minimum detectable activities and the energy resolutions of each were measured and compared. The data were analyzed using different software packages. The measurements were performed in a low background radiation environment using calibrated point sources. The
Search for the triple-escape peak in HPGe detectors
NASA Astrophysics Data System (ADS)
Maidana, N. L.; Tridapalli, D. B.; Rizzutto, M. A.; Pascholati, P. R.; Martins, M. N.; Vanin, V. R.
Triple-escape peaks can be generated when either the electron or the positron created by the pair-formation interaction inside the active volume generates a Bremsstrahlung ?-ray with enough energy to produce another pair; however, they were never observed. MCNP5 and MCNPX simulations differ greatly in the triple-escape peak intensity for photon energies around 6 MeV but agree for 14 MeV incoming photons. An empirical model was developed to check the order of magnitude of the simulated results. An experiment performed to observe the triple-escape peak yielded negative result; the upper limit for the intensity ratio between the triple- and double-escape peaks for 6.13 MeV photons in a 240 cm 3 HPGe detector is 9�10 -4.
Observation of charge-sharing in an HPGe double-sided strip detector
NASA Astrophysics Data System (ADS)
Hayward, Jason; Wehe, David
In double-sided strip high-purity germanium (HPGe) detectors, improved position resolution can be obtained through axial and lateral strip interpolation by means of pulse shape analysis. Yet, only a small fraction of events can be interpolated in both the axial and lateral dimensions, meaning that the best possible imaging performance is delivered at the cost of low imaging efficiency. Lateral position interpolation is complicated by the bipolar nature of induced bystander signals, charge-sharing between neighboring strips, and close interaction sequences. The first two complications were observed in our HPGe double-sided strip detector, and their significance is explored. An algorithm has been developed to calculate detector signals for clouds of drifting charge in three dimensions. Simulated bystander signals are in agreement with the family of waveforms produced in our detector. Based upon simulation, the nature of the bipolar signals and fundamental limits on position resolution are discussed. To determine the significance of charge-sharing, our detector was irradiated with high-energy gamma-ray sources, and then preamplifier signals were digitized and analyzed offline. Charge-sharing between adjacent strips was found to increase with gamma-ray energy, occurring for approximately 18% of all Ba-133 interactions (356 keV) and 30% of all Co-60 interactions (1173 and 1333 keV).
Comparison of background in underground HPGe-detectors in different lead shield configurations.
Hult, Mikael; Lutter, Guillaume; Y�ksel, Ayhan; Marissens, Gerd; Misiaszek, Marcin; Roseng�rd, Ulf
In underground HPGe-detector systems where the cosmic ray induced background is low, it is often difficult to assess the location of background sources. In this study, background counting rates of different HPGe-detectors in different lead shields are reported with the aim of better understanding background sources. To further enhance the understanding of the variations of environmental parameters, the background as a function of time over a long period was also studied. PMID:23602708
Evaluation of Monte Carlo-based calibrations of HPGe detectors for in situ gamma-ray spectrometry
Jonas Boson; Agneta H. Plamboeck; Henrik Rameb�ck; G�ran �gren; Lennart Johansson
The aim of this work was to evaluate the use of Monte Carlo-based calibrations for in situ gamma-ray spectrometry. We have performed in situ measurements at five different sites in Sweden using HPGe detectors to determine ground deposition activity levels of 137Cs from the 1986 Chernobyl accident. Monte Carlo-calculated efficiency calibration factors were compared with corresponding values calculated using a
Application of GEANT4 simulation on calibration of HPGe detectors for cylindrical environmental samples.
Nikolic, J D; Jokovic, D; Todorovic, D; Rajacic, M
The determination of radionuclide activity concentration requires a prior knowledge of the full-energy peak (FEP) efficiency at all photon energies for a given measuring geometry. This problem has been partially solved by using procedures based on Monte Carlo simulations, developed in order to complement the experimental calibration procedures used in gamma-ray measurements of environmental samples. The aim of this article is to apply GEANT4 simulation for calibration of two HPGe detectors, for measurement of liquid and soil-like samples in cylindrical geometry. The efficiencies obtained using a simulation were compared with experimental results, and applied to a realistic measurement. Measurement uncertainties for both simulation and experimental values were estimated in order to see whether the results of the realistic measurement fall within acceptable limits. The trueness of the result was checked using the known activity of the measured samples provided by IAEA. PMID:24894534
Positron annihilation spectroscopy techniques applied to the study of an HPGe detector
NASA Astrophysics Data System (ADS)
Nascimento, E. do; Vanin, V. R.; Maidana, N. L.; Silva, T. F.; Rizzutto, M. A.; Fern�ndez-Varea, J. M.
Doppler Broadening Spectroscopy of the large Ge crystal of an HPGe detector was performed using positrons from pair production of 6.13 MeV ?-rays from the 19F(p,??)16O reaction. Two HPGe detectors facing opposite sides of the Ge crystal acting as target provided both coincidence and singles spectra. Changes in the shape of the annihilation peak were observed when the high voltage applied to the target detector was switched on or off, amounting to somewhat less than 20% when the areas of equivalent energy intervals in the corresponding normalized spectra are compared.
New analytical approach to calibrate the co-axial HPGe detectors including correction for source matrix self-attenuation.
Badawi, Mohamed S; Gouda, Mona M; Nafee, Sherif S; El-Khatib, Ahmed M; El-Mallah, Ekram A
To calibrate the co-axial HPGe semiconductor detectors, we introduce a new theoretical approach based on the Direct Statistical method proposed by Selim and Abbas (1995, 1996) to calculate the full-energy peak efficiency for cylindrical detectors. The present method depends on the accurate analytical calculation of the average path length covered by the photon inside the detector active volume and the geometrical solid angle ?, to obtain a simple formula for the efficiency. In addition, the self attenuation coefficient of the source matrix (with a radius greater than the detector's radius), the attenuation factors of the source container and the detector housing materials are also treated by calculating the average path length within these materials. (152)Eu aqueous radioactive sources covering the energy range from 121 to 1408 keV were used. Remarkable agreement between the measured and the calculated efficiencies was achieved with discrepancies less than 2%. PMID:23023386
A large HPGe detector for the non-destructive radioassay of an ultra-low-background counting facility
M. Fechner; C. Henson; J. Gaffiot; T. Lasserre; A. Letourneau; D. Lhuillier; G. Mention; Th. A. Mueller; R. Qu�val; R. Svoboda
We present the use of a low background counting facility, equipped with a p-type 80% relative efficiency HPGe detector, protected by active and passive shielding, and large enough to count a 10" photo-multiplier tube (PMT). A GEANT4 Monte-Carlo of this detector was developed and tuned to 3% accuracy. We report the U, Th, and K contents in three different types of PMTs used in current neutrino experiments, with accuracies of $\\sim 10$ ppb for U and Th and of $\\sim 15$ ppm for K.
New numerical algorithm method to calibrate the HPGe cylindrical detectors using non-axial extended source geometries.
Nafee, Sherif S; Badawi, Mohamed S; Ahmed, Ayman H
The knowledge of the full-energy peak efficiency for a specific source-detector arrangement is often required in various fields of research and applications, such as the analysis of nuclear waste or environmental samples, where both require modeling because it is not practical to prepare a standard that matches the physical and nuclear properties of every waste or environmental item. Therefore, a new numerical algorithm method (NAM) is proposed in the present work to calibrate the co-axial HPGe cylindrical detectors. Cylindrical sources are used in the calibration process placed perpendicularly to the detector's axis. The self-attenuation and the coincidence summing effects at low source-detector distance are also included in the algorithm. A remarkable agreement between the measured and the calculated efficiencies is achieved with discrepancies less than 3%. PMID:20395155
Underwater gamma-spectrometry with HPGe and NaI(Tl) detectors
P. P. Povinec; I. Osvath; M. S. Baxter
An in situ ?-spectrometer designed for underwater operations consisting of HPGe and NaI(Tl) detectors with electronics, data acquistion and processing electronics, and a supporting system consisting of a hydraulic winch with 1200 m conducting cable is described. The characteristics of the system and results obtained during operational tests and deployment in the Irish and Kara Seas are presented. The spectra
Evaluation of sup 137 Cs in pond sediment with an underwater HPGe detector
Winn, W.G.
The amount of 137Cs was measured in the PAR pond on the Savannah River Site. An underwater HPGe detector was used to inventory the gamma-emitting radionuclides in the sediment of the pond. The description and process of the equipment was given in this report. From the analysis of the compiled data, the drawdown can proceed in radiological guide lines.
Calculation of HPGe efficiency for environmental samples: comparison of EFFTRAN and GEANT4
NASA Astrophysics Data System (ADS)
Nikolic, Jelena; Vidmar, Tim; Jokovic, Dejan; Rajacic, Milica; Todorovic, Dragana
Determination of full energy peak efficiency is one of the most important tasks that have to be performed before gamma spectrometry of environmental samples. Many methods, including measurement of specific reference materials, Monte Carlo simulations, efficiency transfer and semi empirical calculations, were developed in order to complete this task. Monte Carlo simulation, based on GEANT4 simulation package and EFFTRAN efficiency transfer software are applied for the efficiency calibration of three detectors, readily used in the Environment and Radiation Protection Laboratory of Institute for Nuclear Sciences Vinca, for measurement of environmental samples. Efficiencies were calculated for water, soil and aerosol samples. The aim of this paper is to perform efficiency calculations for HPGe detectors using both GEANT4 simulation and EFFTRAN efficiency transfer software and to compare obtained results with the experimental results. This comparison should show how the two methods agree with experimentally obtained efficiencies of our measurement system and in which part of the spectrum do the discrepancies appear. The detailed knowledge of accuracy and precision of both methods should enable us to choose an appropriate method for each situation that is presented in our and other laboratories on a daily basis.
Dead-layer thickness effect for gamma spectra measured in an HPGe p-type detector
Ngo Quang Huy
The present work studies the influence of the dead-layer thickness effect on the gamma spectra of a high purity germanium (HPGe) p-type detector at two different points in time. The study was conducted with the Canberra GC1518 detector, which had a dead-layer thickness of 1.15mm in 2005 and 1.46mm in 2009. The measurement of gamma spectra for the reference point-like
Dead-layer thickness effect for gamma spectra measured in an HPGe p-type detector
Ngo Quang Huy
The present work studies the influence of the dead-layer thickness effect on the gamma spectra of a high purity germanium (HPGe) p-type detector at two different points in time. The study was conducted with the Canberra GC1518 detector, which had a dead-layer thickness of 1.15 mm in 2005 and 1.46 mm in 2009. The measurement of gamma spectra for the
Monte Carlo model of HPGe detectors used in routine lung counting.
Atanackovic, Jovica; Kramer, Gary H; Hogue, Mark
An MCNP model of a pair of planar HPGe detectors (designated as: detector 3 and detector 4), that are used for routine lung counting at AECL, was developed. The model was benchmarked against experimental results, where a multi-line (152)Eu source was counted in several different geometrical arrangements. The best agreement for both detectors was achieved when side and back dead layers (of both detectors) were quadrupled, with respect to the ones quoted by their manufacturer (Canberra). In the case of detector 4, the agreement between simulated and measured spectra was within 4%, throughout the whole ?-spectrum, spanning 70-1600 keV. The same was true for detector 3 at the lower end of the ?-spectrum. However, at the high end of the ?-spectrum, the agreement was within 7% and 12% for (152)Eu ?-lines at 778.9 and 1408.01 keV. PMID:23747513
Determination of dead-layer variation in HPGe detectors.
Andreotti, E; Hult, M; Marissens, G; Lutter, G; Garfagnini, A; Hemmer, S; von Sturm, K
The dead-layer uniformity of the top surface of two high purity germanium detectors has been studied using a novel automated scanning set-up that allows a fine-grained topography of a detector's top and lateral surfaces. Comparisons between measurements and Monte Carlo simulations allowed implementation of a dead-layer variation into the detector model, which reproduces the measurements results. The effect of the non-uniform dead-layer on activity determinations based on low-energy ?-rays (i.e. below ~100 keV) has been determined to be of the order of 10% or more. PMID:24331853
Comparison of the NDA of HEU Oxide between the AWCC and the HPGe Detector
Chiang, L. G.; Oberer, R. B.; Gunn, C. A.; Dukes, E. E.; Akin, J. A.
This paper compares the performance of the Active Well Coincidence Counter (AWCC) with the performance of high resolution gamma spectrometry using an HPGe detector to nondestructively assay highly enriched (HEU) oxide. Traditionally the AWCC was considered to be the more appropriate instrument for this measurement. Although the AWCC had a high degree of precision, the HPGe provided the more accurate measurement of this material. The AWCC determines mass of U-235 from the coincident pairs of neutron detections, or doubles rate. The HPGe determines the mass of both U-235 and U238, the enrichment, and the quantity of other radioisotopes. The Tl-208 gamma rays were used to verify the amount of attenuation for the HPGe analysis. Fifty-four cans of enriched U3O8 were shipped to the Y-12 National Security Complex from Los Alamos National Laboratory (LANL) under Scrap Declaration LANL-45. The declared values for net weight, mass of uranium, mass of U-235, and enrichment (percent mass of U-235 to total uranium) are shown in Table A-1. The masses of U-235 range from 104g to 2404g and the enrichment varies from 20% to 98%.
Surface-Alpha Backgrounds for HPGe Detectors in Neutrinoless Double-Beta Decay Experiments
R. A. Johnson; T. H. Burritt; S. R. Elliott; V. M. Gehman; V. E. Guiseppe; J. F. Wilkerson
The Majorana Experiment will use arrays of enriched HPGe detectors to search for the neutrinoless double-beta decay of ^76Ge. Such a decay, if found, would show lepton-number violation, confirm the Majorana nature of the neutrino, and help determine the effective Majorana neutrino mass. A potentially important background contribution to this and other double-beta decay experiments arises from decays of alpha-emitting
Evaluation of [sup 137]Cs in pond sedment with an underwater HPGe detector
Winn, W.G. (Westinghouse Savannah River Co., Aiken, SC (United States))
At the Savannah River Site during the past year, an underwater high-purity germanium (HPGe) detector was used to inventory [sup 137]Cs in sediment of a reactor cooling pond. Dam maintenance required lowering the water level of the pond by 6 m, and the gamma-emitting radionuclides in the exposed sediment needed preevaluation. Although earlier [sup 137]Cs data were available, there were no comprehensive underwater gamma spectrometric measurements of the sediment.
Triple and quadruple-escape peaks in HPGe detectors: Experimental observation and Monte Carlo simulation
N. L. Maidana; L. Brualla; V. R. Vanin; J. R. B. Oliveira; M. A. Rizzutto; E. do Nascimento; J. M. Fern�ndez-Varea
The triple- and quadruple-escape peaks of 6.128MeV photons from the F(p,??)19O16 nuclear reaction were observed in an HPGe detector. The experimental peak areas, measured in spectra projected with a restriction function that allows quantitative comparison of data from different multiplicities, are in reasonably good agreement with those predicted by Monte Carlo simulations done with the general-purpose radiation-transport code penelope. The
Measurements of radionuclide in Par Pond sediments with an underwater HPGe detector
Savannah River Site (SRS) effluent gamma emitting radionuclides in Par Pond sediment were examined in situ with an underwater HPGe detector prior to and following a 19 ft drawdown of the pond in 1991 to address dam repairs. These measurements provide a map of the ¹³⁷Cs concentrations of the pond sediment, indicating that 9.4 ± 1.5 Ci is exposed by
A high-efficiency HPGe coincidence system for environmental analysis.
Britton, R; Davies, A V; Burnett, J L; Jackson, M J
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is supported by a network of certified laboratories which must meet certain sensitivity requirements for CTBT relevant radionuclides. At the UK CTBT Radionuclide Laboratory (GBL15), a high-efficiency, dual-detector gamma spectroscopy system has been developed to improve the sensitivity of measurements for treaty compliance, greatly reducing the time required for each sample. Utilising list-mode acquisition, each sample can be counted once, and processed multiple times to further improve sensitivity. For the 8 key radionuclides considered, Minimum Detectable Activities (MDA's) were improved by up to 37% in standard mode (when compared to a typical CTBT detector system), with the acquisition time required to achieve the CTBT sensitivity requirements reduced from 6 days to only 3. When utilising the system in coincidence mode, the MDA for (60) Co in a high-activity source was improved by a factor of 34 when compared to a standard CTBT detector, and a factor of 17 when compared to the dual-detector system operating in standard mode. These MDA improvements will allow the accurate and timely quantification of radionuclides that decay via both singular and cascade ? emission, greatly enhancing the effectiveness of CTBT laboratories. PMID:25875083
Triple- and quadruple-escape peaks in HPGe detectors: Experimental observation and Monte Carlo simulation
NASA Astrophysics Data System (ADS)
Maidana, N. L.; Brualla, L.; Vanin, V. R.; Oliveira, J. R. B.; Rizzutto, M. A.; do Nascimento, E.; Fern�ndez-Varea, J. M.
The triple- and quadruple-escape peaks of 6.128 MeV photons from the F(p,??)19O16 nuclear reaction were observed in an HPGe detector. The experimental peak areas, measured in spectra projected with a restriction function that allows quantitative comparison of data from different multiplicities, are in reasonably good agreement with those predicted by Monte Carlo simulations done with the general-purpose radiation-transport code PENELOPE. The behaviour of the escape intensities was simulated for some gamma-ray energies and detector dimensions; the results obtained can be extended to other energies using an empirical function and statistical properties related to the phenomenon.
Mapping radionuclide distribution in surface sediments using GIS and an underwater HPGe detector
Dunn, D.L.; Winn, W.G.; Bresnahan, P.J. [Westinghouse Savannah River Company, Aiken, SC (United States)
Gamma-emitting radionuclides in the surface sediments of L Lake were examined in situ with an underwater High Purity Germanium (HPGe) detector and further studied by retrieving various sediment samples for analysis by HPGe gamma spectrometry. The predominant man-made radio nuclide detected was cesium-137. These measurements were part of a four phase strategy for characterizing L Lake contaminants. The radionuclide distribution data provided by these studies can be directly compared to baseline gamma surveys done in 1985 prior to the lake`s completion. All available data were carefully considered in the preparation of an Environmental Impact Statement (EIS) that evaluates the consequences of discontinuing river water pumping to the man-made cooling water reservoirs at the Savannah River Site.
Alpha Backgrounds for HPGe Detectors in Neutrinoless Double-Beta Decay Experiments
R. A. Johnson; T. H. Burritt; S. R. Elliott; V. M. Gehman; V. E. Guiseppe; J. F. Wilkerson
The Majorana Experiment will use arrays of enriched HPGe detectors to search for the neutrinoless double-beta decay of 76Ge. Such a decay, if found, would show lepton-number violation and confirm the Majorana nature of the neutrino. Searches for such rare events are hindered by obscuring backgrounds which must be understood and mitigated as much as possible. A potentially important background contribution to this and other double-beta decay experiments could come from decays of alpha-emitting isotopes in the 232Th and 238U decay chains on or near the surfaces of the detectors. An alpha particle emitted external to an HPGe crystal can lose energy before entering the active region of the detector, either in some external-bulk material or within the dead region of the crystal. The measured energy of the event will only correspond to a partial amount of the total kinetic energy of the alpha and might obscure the signal from neutrinoless double-beta decay. A test stand was built and measurements were performed to quantitatively assess this background. We present results from these measurements and compare them to simulations using Geant4. These results are then used to measure the alpha backgrounds in an underground detector in situ. We also make estimates of surface contamination tolerances for double-beta decay experiments using solid-state detectors.
Alpha Backgrounds for HPGe Detectors in Neutrinoless Double-Beta Decay Experiments
Johnson, R. A. [University of Washington, Seattle; Burritt, T. H. [University of Washington, Seattle; Elliott, S. R. [Los Alamos National Laboratory (LANL); Gehman, V. M. [Los Alamos National Laboratory (LANL); Guiseppe, V.E. [University of South Dakota; Wilkerson, J. F. [UNC/Triangle Univ. Nucl. Lab, Durham, NC/ORNL
The Majorana Experiment will use arrays of enriched HPGe detectors to search for the neutrinoless double-beta decay of 76Ge. Such a decay, if found, would show lepton-number violation and confirm the Majorana nature of the neutrino. Searches for such rare events are hindered by obscuring backgrounds which must be understood and mitigated as much as possible. A potentially important background contribution to this and other double-beta decay experiments could come from decays of alpha-emitting isotopes in the 232Th and 238U decay chains on or near the surfaces of the detectors. An alpha particle emitted external to an HPGe crystal can lose energy before entering the active region of the detector, either in some external-bulk material or within the dead region of the crystal. The measured energy of the event will only correspond to a partial amount of the total kinetic energy of the alpha and might obscure the signal from neutrinoless double-beta decay. A test stand was built and measurements were performed to quantitatively assess this background. We present results from these measurements and compare them to simulations using Geant4. These results are then used to measure the alpha backgrounds in an underground detector in situ. We also make estimates of surface contamination tolerances for double-beta decay experiments using solid-state detectors.
Search for double beta decay of $^{136}$Ce and $^{138}$Ce with HPGe gamma detector
P. Belli; R. Bernabei; R. S. Boiko; F. Cappella; R. Cerulli; F. A. Danevich; A. Incicchitti; B. N. Kropivyansky; M. Laubenstein; D. V. Poda; O. G. Polischuk; V. I. Tretyak
Search for double $\\beta$ decay of $^{136}$Ce and $^{138}$Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe $\\gamma$ detector with a volume of 465 cm$^3$ at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of $\\lim T_{1/2}\\sim 10^{17}-10^{18}$~yr; many of them are even two orders of magnitude larger than the best previous results.
Cosmic-ray induced background intercomparison with actively shielded HPGe detectors at underground locations
Sz�cs, T; Reinhardt, T P; Schmidt, K; Tak�cs, M P; Wagner, A; Wagner, L; Weinberger, D; Zuber, K
The main background above 3\\,MeV for in-beam nuclear astrophysics studies with $\\gamma$-ray detectors is caused by cosmic-ray induced secondaries. The two commonly used suppression methods, active and passive shielding, against this kind of background were formerly considered only as alternatives in nuclear astrophysics experiments. In this work the study of the effects of active shielding against cosmic-ray induced events at a medium deep location is performed. Background spectra were recorded with two actively shielded HPGe detectors. The experiment was located at 148\\,m below the surface of the Earth in the Reiche Zeche mine in Freiberg, Germany. The results are compared to data with the same detectors at the Earth's surface, and at depths of 45\\,m and 1400\\,m, respectively.
Inhomogeneity effects on HPGe gamma spectrometry detection efficiency using Monte Carlo technique
F. Gharbi
This work deals with the inhomogeneity effects on the full energy peak efficiency determination with HPGe gamma spectrometry. The inhomogeneity of the sample was defined in this work as being the fraction of its volume, which does not contain gamma emitters. We applied the Monte Carlo technique based on the GEANT4 code of CERN to study these effects for soil
Field analyses of (238)U and (226)Ra in two uranium mill tailings piles from Niger using portable HPGe detector.
D�jeant, Adrien; Bourva, Ludovic; Sia, Radia; Galoisy, Laurence; Calas, Georges; Phrommavanh, Vannapha; Descostes, Michael
The radioactivities of (238)U and (226)Ra in mill tailings from the U mines of COMINAK and SOMA�R in Niger were measured and quantified using a portable High-Purity Germanium (HPGe) detector. The (238)U and (226)Ra activities were measured under field conditions on drilling cores with 600s measurements and without any sample preparation. Field results were compared with those obtained by Inductive Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and emanometry techniques. This comparison indicates that gamma-ray absorption by such geological samples does not cause significant deviations. This work shows the feasibility of using portable HPGe detector in the field as a preliminary method to observe variations of radionuclides concentration with the aim of identifying samples of interest. The HPGe is particularly useful for samples with strong secular disequilibrium such as mill tailings. PMID:25036918
Scoping measurements of radionuclides in L Lake with an underwater HPGe detector
Dunn, D.L.; Win, W.G.; Bresnahan, P.J.
This study of L Lake was conducted to determine whether the distribution of man-made radiation levels had changed from the time preceding the filling of the newly created lake in 1985. Overflight gamma measurements by EG&G in 1985 mapped the man-made radiation levels, indicating that significant levels were only detected from former stream beds that were to be covered by the lake. the present scoping gamma measurements were consistent with these earlier findings, indicating no major evidence of movement of the radioactivity. These results will be available to guide decisions concerning future plans for the lake. Gamma-emitting radionuclides of L Lake were examined in situ with an underwater HPGe detector and further studied by retrieving various sediment samples for analysis by HPGe gamma spectrometry in the Underground Counting Facility. The predominant man-made radionuclide detected was {sup 137}Cs; it had about 100 times greater activity than {sup 60}Co, which was the only other man-made radionuclide that was detected above trace levels.
Deterioration of plutonium isotopic analysis with neurtron damage to HPGe detectors
Koenig, Z.M.; Gunnink, R.; Ruhter, W.D.; Camp, D.C.
The effects of neutron (n) damage on HPGe detectors used to measure Pu isotopic ratios were investigated. Both a p-type planar and an n-type coaxial detector were progressively neutron damaged up to a total integrated flux of >5{times}10{sup 9} n/cm{sup 2} from a {sup 252}Cf source. Severe deterioration of selected peak shapes and degradation in the Pu isotopic analysis capability were observed and quantified by using the GRPANL and MGA codes developed at LLNL. After an integrated exposure of 1{times}10{sup 9} n/cm{sup 2} the Pu spectrum from the coaxial detector could not be analyzed with MGA. The planar detector spectrum continued to be analyzable with MGA up to 4{times}10{sup 9} n/cm{sup 2}. Cooling the planar detector to 80 K with an electrically-cooled cryostat could extent its useful lifetime up to an exposure of 2{times}10{sup 10} n/cm{sup 2}. 11 refs., 7 figs. , 1 tab.
Spatial calibration via imaging techniques of a novel scanning system for the pulse shape characterisation of position sensitive HPGe detectors
N. Goel; C. Domingo-Pardo; T. Engert; J. Gerl; I. Kojouharov; H. Schaffner
In this work, a novel imaging technique for the spatial calibration of a gamma camera is presented. The latter is aimed for the characterisation of the charge signals of 3D-position sensitive HPGe detectors. The characterisation method itself is based on pulse shape comparison (PSC) technique. The performance of the device is improved by implementing a gamma camera or position sensitive
Characterisation, modelling and optimisation of the model of a HPGe detector with the aid of point sources
O. Marzocchi; B. Breustedt; M. Urban
A virtual model of a Canberra HPGe detector was produced with the aid of MCNPX and of different point sources. The measured and expected count rates were compared. The initial results showed significant discrepancies, therefore additional parametric simulations have been used to improve the model. As a result, the agreement between theoretical and measured performances in the middle�upper part of
Estimation of background spectrum in a shielded HPGe detector using Monte Carlo simulations.
Medhat, M E; Wang, Yifang
Monte Carlo simulations are powerful tools used to estimate the background ?-radiation detected by high-resolution gamma-ray spectrometry systems with a HPGe (high purity germanium) detector contained inside a lead shield. The purpose of this work was to examine the applicability of Monte Carlo simulations to predict the optimal lead thickness necessary to reduce the background effect in spectrometer measurements. GEANT4 code was applied to simulate the background radiation spectrum at different thicknesses of lead. The simulated results were compared with experimental measurements of background radiation taken at the same shielding thickness. The results show that the background radiation detected depends on the thickness, size and lining of the shield. Simulation showed that 12 cm lead thick is the optimal shielding thickness. PMID:24292007
Improvement studies on neutron-gamma separation in HPGe detectors by using neural networks
Serkan Akkoyun; Tuncay Bayram; S. Okan Kara
The neutrons emitted in heavy-ion fusion-evaporation (HIFE) reactions together with the gamma-rays cause unwanted backgrounds in gamma-ray spectra. Especially in the nuclear reactions, where relativistic ion beams (RIBs) are used, these neutrons are serious problem. They have to be rejected in order to obtain clearer gamma-ray peaks. In this study, the radiation energy and three criteria which were previously determined for separation between neutron and gamma-rays in the HPGe detectors have been used in artificial neural network (ANN) for improving of the decomposition power. According to the preliminary results obtained from ANN method, the ratio of neutron rejection has been improved by a factor of 1.27 and the ratio of the lost in gamma-rays has been decreased by a factor of 0.50.
Measurements of radionuclide in Par Pond sediments with an underwater HPGe detector
Winn, W.G.
Savannah River Site (SRS) effluent gamma emitting radionuclides in Par Pond sediment were examined in situ with an underwater HPGe detector prior to and following a 19 ft drawdown of the pond in 1991 to address dam repairs. These measurements provide a map of the {sup 137}Cs concentrations of the pond sediment, indicating that 9.4 {plus_minus} 1.5 Ci is exposed by the drawdown and that 46.6 {plus_minus} 7.2 Ci is the entire pond inventory. The highest individual {sup 137}Cs concentration was 25 {mu}Ci/m{sup 2} for the exposed sediment and 50 {mu}Ci/m{sup 2} for the entire pond. The results are consistent with parallel studies conducted by SREL, as well as historical data. Aside from {sup 137}Cs, the only other SRS-produced isotope observed was {sup 60}Co, with activity of only about 1% of that for {sup 137}Cs. This observation was also confirmed in grab samples of pond sediment and vegetation, which were returned to the laboratory for ultra-low-level gamma spectrometry analysis. A special effort was required to calibrate the underwater HPGe detector, where both measurements and calculational models were used. The effects of sediment depth profiles for density and {sup 137}Cs concentration were addressed in the calibration. Calibration factors for sediment surface concentrations ({mu}Ci/m{sup 2}/cpm) and sediment mass concentrations (pCi/kg/cpm) were obtained. In general, the {mu}Ci/m{sup 2}/cpm factor is recommended, as the pCi/kg/cpm factor depends on the depth location of the sediment of interest. However, a pCi/kg/cpm factor, which is dependent on the depth within the sediment is presented to address dose calculations that require it.
Response of AGATA segmented HPGe detectors to gamma-rays up to 15.1 MeV
F. C. L. Crespi; R. Avigo; F. Camera; G. Benzoni; N. Blasi; S. Bottoni; A. Bracco; S. Brambilla; P. Casati; F. Coniglio; A. Corsi; A. Giaz; S. Leoni; B. Million; R. Nicolini; L. Pellegri; S. Riboldi; V. Vandone; O. Wieland; S. Akkoyun; A. Atac; D. Bazzacco; M. Bellato; D. Bortolato; E. Calore; M. Ciemala; E. Farnea; A. Gadea; A. Gottardo; M. Kmiecik; A. Maj; D. Mengoni; C. Michelagnoli; D. Montanari; D. R. Napoli; J. Nyberg; F. Recchia; E. Sahin; P.-A. Soderstrom; C. Ur; J. J. Valiente Dobon
In many in-beam gamma spectroscopy experiments the detection of high-energy gamma rays in the range up to 10�20 MeV is of primary importance. New generation high-resolution gamma-ray spectrometers like AGATA and GRETA are composed of position sensitive segmented HPGe detectors and provide a reconstruction of the gamma-ray tracks. The performance of AGATA detectors in this energy range has, however, never
Spectral Study of a Broad Energy HPGe Detector for First Measurement of Coherent Neutrino Scattering
NASA Astrophysics Data System (ADS)
Surbrook, Jason; Green, Matthew
Intense neutrino flux at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) in the energy domain below E? = 50 MeV makes SNS a suitable location for measurement of Coherent Neutrino Scattering. Coherent scattering is assumed to occupy vital roles in supernovae (SN) events and measurement offers promising insight into SN mechanics and advancements in SN- ? detection. Furthermore, this interaction is well-calculable and therefore, a strong test of the Standard Model. P-Type Point Contact High-purity germanium detectors are excellent candidates for this measurement due to their sensitivity to low-energy nuclear recoils. One such, a Canberra Broad Energy HPGe detector, was tested for quality degradation from exposure to fast neutrons in the SNS target building, to assess usefulness in a future coherent scattering experiment. Analysis of the lead-shielded spectra was handled using tools developed for the Majorana Demonstrator neutrinoless double-beta decay experiment. Broad spectrum energy resolution and 68Ge decay rates were calculated. This poster will present findings that will help determine this detector's eligibility and exposure limitations for measurement in a future coherent neutrino scattering experiment at the SNS.
Estimation of immediate fallout after the accident at Fukushima Daiichi Nuclear Power Plant by using HPGe detector and EGS5 code.
Unno, Yasuhiro; Yunoki, Akira; Sato, Yasushi; Hino, Yoshio
After the accident at the Fukushima Daiichi nuclear power plant, we managed to carry out emergency measurements of the radioactive fallout. The included nuclides were identified via gamma-ray spectrometry using an HPGe detector. Quantifications of each radionuclide in the fallout were determined based on the efficiency calibrations and relevant corrections. The collected samples had a variety of shapes, densities, and compositions. EGS5 Monte Carlo code was used for the flexible estimation of these parameters. The measurement results show the temporal changes in the fallout quantity about a month after the accident. PMID:23570955
Uncertainty in HPGe detector calibrations for in situ gamma-ray spectrometry.
Boson, Jonas; Johansson, Lennart; Rameb�ck, Henrik; Agren, G�ran
Semi-empirical methods are often used for efficiency calibrations of in situ gamma-ray spectrometry measurements with high-purity germanium detectors. The intrinsic detector efficiency is experimentally determined for different photon energies and angles of incidence, and a suitable expression for the efficiency is fitted to empirical data. In this work, the combined standard uncertainty of such an efficiency function for two detectors was assessed. The uncertainties in individual efficiency measurements were found to be about 1.9 and 3.1% (with a coverage factor k = 1, i.e. with a confidence interval of about 68%) for the two detectors. The main contributions to these uncertainties were found to originate from uncertainties in source-to-detector distance, source activity and full-energy peak count rate. The standard uncertainties of the fitted functions were found to be somewhat higher than the uncertainty of individual data points, i.e. 5.2 and 8.1% (k = 1). With the introduction of a new expression for the detector efficiency, these uncertainties were reduced to 3.7 and 4.2%, i.e. with up to a factor of two. Note that this work only addresses the uncertainty in the determination of intrinsic detector efficiency. PMID:19429646
Double {beta} experiments with the help of scintillation and HPGe detectors at Gran Sasso
Barabash, A.; Konovalov, S. I.; Umatov, V. I. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Belli, P.; D'Angelo, S.; Di Marco, A. [INFN, Sezione di Roma ''Tor Vergata'', Rome (Italy); Bernabei, R. [INFN, Sezione di Roma ''Tor Vergata '', Rome (Italy); Dipartimento di Fisica, Universita di Roma ''Tor Vergata'', Rome (Italy); Boiko, R. S.; Chernyak, D. M.; Danevich, F. A.; Kobychev, V. V.; Kropivyansky, B. N.; Kudovbenko, V. M.; Nagorny, S. S.; Podviyanuk, R. B.; Polischuk, O. G.; Tretyak, V. I.; Vyshnevskyi, I. M.; Yurchenko, S. S. [Institute for Nuclear Research, Kyiv (Ukraine); Brudanin, V. B. [Joint Institute for Nuclear Research, Dubna (Russian Federation); and others
A search for double beta decay of {sup 64,70}Zn, {sup 180,186}W was carried out by using low background ZnWO{sub 4} crystal scintillators, while a CeCl{sub 3} scintillation detector was applied to investigate 2{beta} processes in {sup 136,138,142}Ce. A search for 2{beta} decay of {sup 96,104}Ru, {sup 156,158}Dy, {sup 190,198}Pt and study of 2{nu}2{beta} decay of {sup 100}Mo to the first excited 0{sup +} level of {sup 100}Ru were realized by ultra-low background HPGe {gamma} spectrometry. Moreover, CdWO{sub 4} crystal scintillators from enriched {sup 106}Cd and {sup 116}Cd isotopes were developed to search for 2{beta} decay of {sup 106}Cd and {sup 116}Cd. Finally, experiments aimed to investigate {sup 96,104}Ru and {sup 116}Cd are in progress and a new phase of the experiment to search for 2{beta} processes in {sup 106}Cd is in preparation.
A Monte Carlo simulation of background characteristics of low-level HPGe detectors
Vojtyla; Povinec
The radionuclide levels observed at present in the marine environment are very low, therefore high sensitive spectrometric systems are required for carrying out oceanographic investigations. The present-state-of-the-art carefully designed low-level HPGe gamma-spectrometers, which do not operate underground, have a dominating background component induced by cosmic rays, mostly by cosmic muons. High energy cosmic rays can initiate a large number of physical processes leading to background induction. Analytic solutions for describing these processes are not available and therefore, a Monte Carlo simulation is necessary. The development of a simulation code for background induction is useful for the optimisation of a counting system in respect to its background characteristics. It enables to assert the background before the system is built and also to perform systematic investigation of the influence of various parameters on the background of the detector. The GEANT code has been selected from the codes systems facilitating the simulation of the passage of particles through matter, as it best meets the requirements for simulations with high-energy muons. The obtained results show that the background depends most significantly on the thickness, the size and lining of the shield. Lead shielding of 15 cm thick has been found to be the optimum shielding for most applications. It is not advisable to build an unnecessarily large shield. A shield with removable lining would be the best as the lining can be removed from applications where the lead X-rays are not a disturbing influence. PMID:10879859
Measurement of real and imaginary form factors of silver atom using a high resolution HPGe detector.
Krishnananda; Niranjana, K M; Badiger, N M
The real and imaginary form factors of silver atom have been determined by using EDXRF method. The K x-ray photons in the energy range from 8.62 keV to 52.18 keV are generated by sending 59.56 keV gamma photons from
Calibration of HPGe gamma-ray detectors for measurement of radioactive noble gas sources
L. Pibida; S. S. Nafee; M. Unterweger; M. M. Hammond; L. Karam; M. I. Abbas
Measurements of radioactive noble gases are routinely made with gamma-ray spectrometers. This work describes the calibration of high purity germanium detectors provided by the full-energy-peak efficiency as a function of the gamma-ray energy. A comparison of measured efficiency values with a new, simplified method based on a direct mathematical method is given here.
19F (p, alpha gamma) 16O reaction: HPGe detector response function and gamma-ray relative yields
D. B. Tridapalli; P. R. Pascholati; N. L. Maidana; V. R. Vanin; Z. O. Guimar�es-Filho; M. A. Rizzutto
The 6.1, 6.9 and 7.1 MeV photon yields in the reaction with protons in the 1.32 to 1.42 MeV energy range were determined from the comparison between experimental and simulated spectrum. The gamma-ray spectra were measured with a HPGe detector which was 72.5 mm in diameter and 60.5 mm in length. The reaction kinematics and the detector response function were simulated by different programs using the Monte Carlo method. The relative photon yields were obtained from the least-squares fit of the experimental gamma-ray spectra to the convolution of the detector response function with the photon energy distribution arising from the reaction kinematics.
19F (p, alpha gamma) 16O reaction: HPGe detector response function and gamma-ray relative yields
Tridapalli, D B; Maidana, N L; Vanin, V R; Guimar�es-Filho, Z O; Rizzutto, M A
The 6.1, 6.9 and 7.1 MeV photon yields in the reaction with protons in the 1.32 to 1.42 MeV energy range were determined from the comparison between experimental and simulated spectrum. The gamma-ray spectra were measured with a HPGe detector which was 72.5 mm in diameter and 60.5 mm in length. The reaction kinematics and the detector response function were simulated by different programs using the Monte Carlo method. The relative photon yields were obtained from the least-squares fit of the experimental gamma-ray spectra to the convolution of the detector response function with the photon energy distribution arising from the reaction kinematics.
High efficiency photoionization detector
Anderson, D.F.
A high efficiency photoionization detector is described using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36 [+-] 0.02 eV, and a vapor pressure of 0.35 torr at 20 C. 6 figs.
Consistent empirical physical formula construction for recoil energy distribution in HPGe detectors using artificial neural networks
Serkan Akkoyun; Nihat Yildiz
The gamma-ray tracking technique is one of the highly efficient detection method in experimental nuclear structure physics. On the basis of this method, two gamma-ray tracking arrays, AGATA in Europe and GRETA in the USA, are currently being developed. The interactions of neutrons in these detectors lead to an unwanted background in the gamma-ray spectra. Thus, the interaction points of neutrons in these detectors have to be determined in the gamma-ray tracking process in order to improve photo-peak efficiencies and peak-to-total ratios of the gamma-ray peaks. Therefore, the recoil energy distributions of germanium nuclei due to inelastic scatterings of 1-5 MeV neutrons were obtained both experimentally and using artificial neural networks. Also, for highly nonlinear detector response for recoiling germanium nuclei, we have constructed consistent empirical physical formulas (EPFs) by appropriate layered feed-forward neural networks (LFNNs). These LFNN-EPFs can be used to derive further physical functions which could be relevant to determination of neutron interactions in gamma-ray tracking process.
Response of AGATA Segmented HPGe Detectors to Gamma Rays up to 15.1 MeV
F. C. L. Crespi; R. Avigo; F. Camera; S. Akkoyun; A. Atac; D. Bazzacco; M. Bellato; G. Benzoni; N. Blasi; D. Bortolato; S. Bottoni; A. Bracco; S. Brambilla; B. Bruyneel; S. Cerutia; M. Ciemala; S. Coelli; J. Eberth; C. Fanin; E. Farnea; A. Gadea; A. Giaz; A. Gottardo; H. Hess; M. Kmiecik; S. Leoni; A. Maj; D. Mengoni; C. Michelagnoli; B. Million; D. Montanari; L. Pellegri; F. Recchia; P. Reiter; S. Riboldi; C. A. Ur; V. Vandone; J. J. Valiente-Dobon; O. Wieland; A. Wiens; The AGATA Collaboration
The response of AGATA segmented HPGe detectors to gamma rays in the energy range 2-15 MeV was measured. The 15.1 MeV gamma rays were produced using the reaction d(11B,ng)12C at Ebeam = 19.1 MeV, while gamma-rays between 2 to 9 MeV were produced using an Am-Be-Fe radioactive source. The energy resolution and linearity were studied and the energy-to-pulse-height conversion resulted to be linear within 0.05%. Experimental interaction multiplicity distributions are discussed and compared with the results of Geant4 simulations. It is shown that the application of gamma-ray tracking allows a suppression of background radiation following neutron capture by Ge nuclei. Finally the Doppler correction for the 15.1 MeV gamma line, performed using the position information extracted with Pulse-shape Analysis, is discussed.
Efficiencies of Quantum Optical Detectors
Daniel Hogg; Dominic W. Berry; A. I. Lvovsky
We propose a definition for the efficiency that can be universally applied to all classes of quantum optical detectors. This definition is based on the maximum amount of optical loss that a physically plausible device can experience while still replicating the properties of a given detector. We prove that detector efficiency cannot be increased using linear optical processing. That is, given a set of detectors, as well as arbitrary linear optical elements and ancillary light sources, it is impossible to construct detection devices that would exhibit higher efficiencies than the initial set.
Mapping of true coincidence effect value for voluminous sources measured with HPGE
NASA Astrophysics Data System (ADS)
Kolotov, V. P.; Atrashkevich, V. V.; Dogadkin, N. N.
Based on the methodology of the full peak efficiency mapping of HPGe detectors, a means to model the computation of the true coincidence effect inside a voluminous sample was developed. A summing-in and a summing-out case are used as examples to illustrate the magnitude of the true coincidence effect for a 60% HPGe. The applicability of the intrinsic P/T-calibration in the course of the integration of the coincidence effect is also discussed.
The use of Geant4 for simulations of a plastic beta-detector and its application to efficiency calibration
V. V. Golovko; V. E. Iacob; J. C. Hardy
Precise beta-branching-ratio measurements are required in order to determine ft-values as a part of our program to test the Electroweak Standard Model via unitarity of the Cabibbo-Kobayashi-Moskawa matrix. For the measurements to be useful in this test, their precision must be close to 0.1 %. In a branching-ratio measurement, we position the radioactive sample between a thin plastic scintillator used to detect beta-particles, and a HPGe detector for gamma-rays. Both beta singles and beta-gamma coincidences are recorded. Although the branching ratio depends most strongly on the HPGe detector efficiency, it has some sensitivity to the energy dependence of the beta-detector efficiency. We report here on a study of our beta-detector response function, which used Monte Carlo calculations performed by the Geant4 toolkit. Results of the simulations are compared to measured beta-spectra from several standard beta-sources.
Experimentally determined vs. Monte Carlo simulated peak-to-valley ratios for a well-characterised n-type HPGe detector.
Ostlund, Karl; Samuelsson, Christer; R��f, Christopher L
Measurements and simulations to investigate the contributing factors to the peak-to-valley (PTV) ratio have been both experimentally determined as well as Monte Carlo simulated for a well-characterised HPGe n-type detector together with a Cs-137 gamma source encapsulated in thin polystyrene. Measurements were carried out in a low-background gamma counting facility at Lund University. The results of the PTV ratio have been compared to distinguish what components or variables in the setup that significantly influence the ratio. In addition to manufacture specifications, the detector components have been examined using planar X-ray, source scanning and computer tomography in order to determine and verify component dimensions when necessary. In spite of these efforts a discrepancy of approximately 25% for thin absorbers in the PTV ratio between measurements and calculations is observed. However, this discrepancy becomes less significant for larger absorbing layers of copper (>1mm). This indicates that it would be difficult to achieve a field calibration for in-situ gamma spectrometry using the PTV ratio that could position a Cs-137 source in soil depth shallower than corresponding 1mm layer of copper. The results also showed that when building a detector in simulations part by part, the inner dead layer, and the contact pin are of great importance for the accuracy of the PTV ratio simulations. PMID:25464184
Efficient scalable solid-state neutron detector
NASA Astrophysics Data System (ADS)
Moses, Daniel
We report on scalable solid-state neutron detector system that is specifically designed to yield high thermal neutron detection sensitivity. The basic detector unit in this system is made of a 6Li foil coupled to two crystalline silicon diodes. The theoretical intrinsic efficiency of a detector-unit is 23.8% and that of detector element comprising a stack of five detector-units is 60%. Based on the measured performance of this detector-unit, the performance of a detector system comprising a planar array of detector elements, scaled to encompass effective area of 0.43 m2, is estimated to yield the minimum absolute efficiency required of radiological portal monitors used in homeland security.
Determination of the hit locations in segmented HPGe detectors without the use of simulations or scanning systems
P. D�sesquelles
A new method is proposed which allows the building of a signal basis, i.e. a matrix of traces corresponding to identified locations of gamma interactions with the crystal, directly from a set of signals delivered by the detector. The usual on-line algorithms dedicated to the location of the hits can apply this basis to perform signal decomposition. The method also
Methods and software for predicting germanium detector absolute full-energy peak efficiencies
K. R. Jackman; S. R. Biegalski
High-purity germanium (HPGe) and lithium drifted germanium (Ge(Li)) detectors have been the detector of choice for high resolution\\u000a gamma-ray spectroscopy for many years. This is primarily due to the superior energy resolution that germanium detectors present\\u000a over other gamma-ray detectors. In order to perform quantitative analyses with germanium detectors, such as activity determination\\u000a or nuclide identification, one must know the
An Efficient Ant-Based Edge Detector
NASA Astrophysics Data System (ADS)
Ayd?n, Do?an
An efficient ant-based edge detector is presented. It is based on the distribution of ants on an image, ants try to find possible edges by using a state transition function based on 5x5 edge structures. Visual comparisons show that the proposed method gives finer details and thinner edges at lesser computational times when compared to earlier ant-based approaches. When compared to standard edge detectors, it shows robustness to Gaussian and Salt & Pepper noise and provides finer details than others with same parameter set in both clear and noisy images.
Determination of Barium and selected rare-earth elements in geological materials employing a HpGe detector by radioisotope excited x-ray fluorescence
LaBrecque, J.J.; Preiss, I.L. (Instituto Venezolano de Investigaciones Cientificas, Caracas. Dept. de Fisica Atomica y Molecular)
The laterite material (geological) from Cerro Impacto was first studied by air radiometric techniques in the 1970's and was found to have an abnormally high radioactive background. Further studies showed this deposit to be rich in thorium, columbium, barium and rare-earth elements (mostly La, Ce, Pr and Nd). A similar work has been reported for the analysis of Brazil's lateritic material from Morro do Ferro to determine elemental compositions (including barium and rare-earth elements) and its relationship to the mobilization of thorium from the deposit using a Co-57 radioisotope source. The objective of this work was to develop an analytical method to determine barium and rare-earth element present in Venezuelan lateritic material from Cerro Impacto. We have employed a method before, employing a Si(Li) detector, but due to the low detection efficiencies in the rare-earth K-lines region (about 30 KeV - 40 KeV), we have decided to study the improvement in sensitivities and detection limits using an hyperpure germanium detector.
Direct modeling of external quantum efficiency of silicon trap detectors
Thiago Menegotto; Maur�cio S. Lima; Giovanna B. Almeida; Iakyra B. Couceiro; Hans Peter Grieneisen
It is shown the feasibility of direct fitting of external quantum efficiency for silicon trap detectors which are applied as radiometric transfer standards at several National Institutes of Metrology. The model considers the internal quantum efficiency and the reflectance of the detector, whose parameters are fitted in the measured data of external quantum efficiency. The advantage of the suggested approach
Measurement of radionuclide activities induced in target components of an IBA CYCLONE 18/9 by gamma-ray spectrometry with HPGe and LaBr3: Ce detectors.
Tomarchio, Elio
Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disposal. Gamma-ray spectrometric analyses were carried out with High Purity Germanium (HPGe) and Lanthanum bromide (LaBr3:Ce) scintillation detectors. HPGe is the most used detector for its high energy resolution although it is more suitable for use in a laboratory. The use of LaBr3:Ce can be considered a viable option, particularly in realizing a portable spectrometric system to perform "on-site" measurements and a fast dose rate evaluation before the disposal of activated parts. Due to a high activity of target assembly components replaced after a typical irradiation cycle (about 5000 ?Ah integrated beam current), gamma-ray spectrometric measurements were performed at a large distance from the detector, even more than 100 cm, or by using a purposely realized Lead-walled collimator. The identification of some key-radionuclides allows to evaluate through simple formulations the dose rate behavior for each component as function of decay time from the last irradiation. The knowledge of the dose rate behavior is a significant piece of information to health physicists for waste handling with safety at work. For an Havar� foil, the dose rate will be reduced to about 1/1,000 of the starting value after a decay period of approximately 4 y (about 1,500 d), with a relatively safety at product disposal work. For a longer time, only long-lived radionuclides (57)Co, (60)Co, and (54)Mn contribute to dose rate. PMID:24949919
Evaluation of the neutron background in an HPGe target for WIMP direct detection when using a reactor neutrino detector as a neutron veto system
Ji, Xiangpan; Xu, Ye, E-mail: firstname.lastname@example.com; Lin, Junsong; Feng, Yulong; Li, Haolin [Nankai University, School of Physics (China)
A direct WIMP (weakly interacting massive particle) detector with a neutron veto system is designed to better reject neutrons. The experimental configuration is studied in this paper involves 984 Ge modules placed inside a reactor-neutrino detector. The neutrino detector is used as a neutron veto device. The neutron background for the experimental design is estimated using the Geant4 simulation. The results show that the neutron background can decrease to O(0.01) events per year per tonne of high-purity germanium and it can be ignored in comparison with electron recoils.
Efficiency study of a big volume well type NaI(Tl) detector by point and voluminous sources and Monte-Carlo simulation.
Hansman, Jan; Mrdja, Dusan; Slivka, Jaroslav; Krmar, Miodrag; Bikit, Istvan
The activity of environmental samples is usually measured by high resolution HPGe gamma spectrometers. In this work a set-up with a 9in.x9in. NaI well-detector with 3in. thickness and a 3in.�3in. plug detector in a 15-cm-thick lead shielding is considered as an alternative (Hansman, 2014). In spite of its much poorer resolution, it requires shorter measurement times and may possibly give better detection limits. In order to determine the U-238, Th-232, and K-40 content in the samples by this NaI(Tl) detector, the corresponding photopeak efficiencies must be known. These efficiencies can be found for certain source matrix and geometry by Geant4 simulation. We found discrepancy between simulated and experimental efficiencies of 5-50%, which can be mainly due to effects of light collection within the detector volume, an effect which was not taken into account by simulations. The influence of random coincidence summing on detection efficiency for radionuclide activities in the range 130-4000Bq, was negligible. This paper describes also, how the efficiency in the detector depends on the position of the radioactive point source. To avoid large dead time, relatively weak Mn-54, Co-60 and Na-22 point sources of a few kBq were used. Results for single gamma lines and also for coincidence summing gamma lines are presented. PMID:25769009
Simulation of background reduction and Compton depression in low-background HPGe spectrometer at a surface laboratory
ShunLi Niu; Xiao Cai; ZhenZhong Wu; YuGuang Xie; BoXiang Yu; ZhiGang Wang; Jian Fang; XiLei Sun; LiJun Sun; YingBiao Liu; Long Gao; Xuan Zhang; Hang Zhao; Li Zhou; JunGuang Lv; Tao Hu
High-purity germanium detectors are well suited to analysis the radioactivity of samples. In order to reduce the environmental background, low-activity lead and oxygen free copper are installed outside of the probe to shield gammas, outmost is a plastic scintillator to veto the cosmic rays, and an anti-Compton detector can improve the Peak-to-Compton ratio. Using the GEANT4 tools and taking into account a detailed description of the detector, we optimize the sizes of the detectors to reach the design indexes. A group of experimental data from a HPGe spectrometer in using were used to compare with the simulation. As to new HPGe Detector simulation, considering the different thickness of BGO crystals and anti-coincidence efficiency, the simulation results show that the optimal thickness is 5.5cm, and the Peak-to-Compton ratio of 40K is raised to 1000 when the anti-coincidence efficiency is 0.85. As the background simulation, 15 cm oxygen-free copper plus 10 cm lead can reduce the environmental gamma rays to 0.0024 cps/100 cm3 Ge (50keV~2.8MeV), which is about 10-5 of environmental background.
Measurements of electron detection efficiencies in solid state detectors.
NASA Technical Reports Server (NTRS)
Lupton, J. E.; Stone, E. C.
Detailed laboratory measurement of the electron response of solid state detectors as a function of incident electron energy, detector depletion depth, and energy-loss discriminator threshold. These response functions were determined by exposing totally depleted silicon surface barrier detectors with depletion depths between 50 and 1000 microns to the beam from a magnetic beta-ray spectrometer. The data were extended to 5000 microns depletion depth using the results of previously published Monte Carlo electron calculations. When the electron counting efficiency of a given detector is plotted as a function of energy-loss threshold for various incident energies, the efficiency curves are bounded by a smooth envelope which represents the upper limit to the detection efficiency. These upper limit curves, which scale in a simple way, make it possible to easily estimate the electron sensitivity of solid-state detector systems.
New Factor Graph Based Multiuser Detector for Spectrally Efficient CPM
Noels, Nele
detector for SE CPM. The proposed receiver algorithm will be referred to as g6-MU-FG-GA. Numerical results indicate that, for a set of system parameters yielding high spectral efficiency, the novel g6-MU CPM sys- tems. Section III describes the considered system model. The proposed g6-MU-FG-GA detector
Absolute Efficiency Calibration of a Beta-Gamma Detector
Cooper, Matthew W.; Ely, James H.; Haas, Derek A.; Hayes, James C.; McIntyre, Justin I.; Lidey, Lance S.; Schrom, Brian T.
Abstract- Identification and quantification of nuclear events such as the Fukushima reactor failure and nuclear explosions rely heavily on the accurate measurement of radioxenon releases. One radioxenon detection method depends on detecting beta-gamma coincident events paired with a stable xenon measurement to determine the concentration of a plume. Like all measurements, the beta-gamma method relies on knowing the detection efficiency for each isotope measured. Several methods are commonly used to characterize the detection efficiency for a beta-gamma detector. The most common method is using a NIST certified sealed source to determine the efficiency. A second method determines the detection efficiencies relative to an already characterized detector. Finally, a potentially more accurate method is to use the expected sample to perform an absolute efficiency calibration; in the case of a beta-gamma detector, this relies on radioxenon gas samples. The complication of the first method is it focuses only on the gamma detectors and does not offer a solution for determining the beta efficiency. The second method listed is not similarly constrained, however it relies on another detector to have a well-known efficiency calibration. The final method using actual radioxenon samples to make an absolute efficiency determination is the most desirable, but until recently it was not possible to produce all four isotopically pure radioxenon. The production, by University of Texas (UT), of isotopically pure radioxenon has allowed the beta-gamma detectors to be calibrated using the absolute efficiency method. The first four radioxenon isotope calibration will be discussed is this paper.
Environmental measurements at the Savannah River Site with Underwater gamma detectors
Winn, W.G.
Underwater NAI(Tl) and HPGe detectors are used in the environmental measurements programs at the Savannah River Site (SRS). A 22.9 cm {times} 10.2 cm NAI(Tl) detector on the Savannah River continuously monitors effluent releases from both SRS (DOE) and Plant Vogtle (Georgia Power). Correlations with known releases indicate a sensitivity of 4 mBq/l for {sup 58}Co with 1500 min spectra; such levels are well below those of hazardous or legal concern. A 30%-efficient HPGE detector has appraised radionuclides in SRS cooling pond sediments; the dominant gamma-emitting radionuclide detected was {sup 137}Cs, at levels ranging up to 2.0 MBq/m{sup 2}. The pond activities were adequately quantified by 1 min counts with the HPGE detector; resulting contour maps of sediment {sup 137}Cs provided guidance for partially draining the ponds for dam repairs.
High efficiency proportional neutron detector with solid liner internal structures
Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.
A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.
Coincidence Efficiency of Sodium Iodide Detectors for Positron Annihilation
NASA Astrophysics Data System (ADS)
Eckert, Thomas; Vincett, Laurel; Yuly, Mark; Padalino, Stephen; Russ, Megan; Bienstock, Mollie; Simone, Angela; Ellison, Drew; Desmitt, Holly; Sangster, Craig; Regan, Sean
One possible diagnostic technique for characterizing inertial confinement fusion reactions uses tertiary neutron activation of 12C via the 12C(n, 2n)11C reaction. A recent experiment to measure this cross section involved counting the positron annihilation gamma rays from the 11C decay by using sodium iodide detectors in coincidence. To determine the number of 11C decays requires an accurate value for the full-peak coincidence efficiency for the detector system. A new technique has been developed to measure this coincidence efficiency by detecting the positron prior to its annihilation, and vetoing events in which decay gamma rays other than the 511 keV annihilation gamma rays could enter the detectors. Measurements and simulation results for the absolute coincidence total and full-peak efficiencies are presented. Funded in part by a grant from the DOE through the Laboratory for Laser Energetics.
MaMP and FeMP: computational mesh phantoms applied for studying the variation of WBC efficiency using a NaI(Tl) detector.
Ferreira Fonseca, T C; Bogaerts, R; Lebacq, A L; Ribeiro, R M; Vanhavere, F
In a previous study, the counting efficiency calibration was calculated for 36 computational mesh phantoms called MaMP and FeMP-Male and Female Mesh Phantoms, which span variations in height, weight and gender. They were created to be used in a sitting configuration WBC set-up using an HPGe detector. Now this work is extended to investigate the influence of body sizes and the position of the detector on the counting efficiency (CE) for a different counting geometry. This was done by creating a new set of MaMP and FeMP mesh phantoms lying on a reclining chair and by studying the variation of the counting efficiency using a NaI(Tl) detector for the WBC set-up of SCK-CEN. The deviation of the CE due to the detector's position with respect to the phantom was investigated. Correlations were also studied for CE as a function of trunk volume, waist-hips ratio (WHR) and waist-chest ratio (WCR) for different mesh phantoms. PMID:24938683
Testing the Ge Detectors for the MAJORANA DEMONSTRATOR
NASA Astrophysics Data System (ADS)
Xu, W.; Abgrall, N.; Aguayo, E.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, J.; MacMullin, S.; Martin, R. D.; Meijer, S.; Mertens, S.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G.; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Suriano, A. M.; Thompson, J.; Timkin, V.; Tornow, W.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.
High purity germanium (HPGe) crystals will be used for the MAJORANA DEMONSTRATOR, where they serve as both the source and the detector for neutrinoless double beta decay. It is crucial for the experiment to understand the performance of the HPGe crystals. A variety of crystal properties are being investigated, including basic properties such as energy resolution, efficiency, uniformity, capacitance, leakage current and crystal axis orientation, as well as more sophisticated properties, e.g. pulse shapes and dead layer and transition layer distributions. In this talk, we will present our measurements that characterize the HPGe crystals. We will also discuss the our simulation package for the detector characterization setup, and show that additional information can be extracted from data-simulation comparisons.
Testing the Ge detectors for the MAJORANA DEMONSTRATOR
W. Xu; N. Abgrall; E. Aguayo; F. T. Avignone III; A. S. Barabash; F. E. Bertrand; M. Boswell; V. Brudanin; M. Busch; D. Byram; A. S. Caldwell; Y-D. Chan; C. D. Christofferson; D. C. Combs; C. Cuesta; J. A. Detwiler; P. J. Doe; Yu. Efremenko; V. Egorov; H. Ejiri; S. R. Elliott; J. E. Fast; P. Finnerty; F. M. Fraenkle; A. Galindo-Uribarri; G. K. Giovanetti; J. Goett; M. P. Green; J. Gruszko; V. E. Guiseppe; K. Gusev; A. L. Hallin; R. Hazama; A. Hegai; R. Henning; E. W. Hoppe; S. Howard; M. A. Howe; K. J. Keeter; M. F. Kidd; O. Kochetov; S. I. Konovalov; R. T. Kouzes; B. D. LaFerriere; J. Leon; L. E. Leviner; J. C. Loach; J. MacMullin; S. MacMullin; R. D. Martin; S. Meijer; S. Mertens; M. Nomachi; J. L. Orrell; C. O'Shaughnessy; N. R. Overman; D. G. Phillips II; A. W. P. Poon; K. Pushkin; D. C. Radford; J. Rager; K. Rielage; R. G. H. Robertson; E. Romero-Romero; M. C. Ronquest; A. G. Schubert; B. Shanks; T. Shima; M. Shirchenko; K. J. Snavely; N. Snyder; A. M. Suriano; J. Thompson; V. Timkin; W. Tornow; J. E. Trimble; R. L. Varner; S. Vasilyev; K. Vetter; K. Vorren; B. R. White; J. F. Wilkerson; C. Wiseman; E. Yakushev; A. R. Young; C. H. Yu; V. Yumatov
High purity germanium (HPGe) crystals will be used for the MAJORANA DEMONSTRATOR, where they serve as both the source and the detector for neutrinoless double beta decay. It is crucial for the experiment to understand the performance of the HPGe crystals. A variety of crystal properties are being investigated, including basic properties such as energy resolution, efficiency, uniformity, capacitance, leakage current and crystal axis orientation, as well as more sophisticated properties, e.g. pulse shapes and dead layer and transition layer distributions. In this paper, we will present our measurements that characterize the HPGe crystals. We will also discuss our simulation package for the detector characterization setup, and show that additional information can be extracted from data-simulation comparisons.
Existing NaI detectors; an efficient alternative to He-3 detectors
NASA Astrophysics Data System (ADS)
Metwally, Walid A.
Neutron detectors are important in various fields of research, safeguards, security, medicine, and industry. The most common methods for detecting neutrons involve utilization of the 10B(n,?), 6Li(n,?), or 3He(n,p) reactions; with the He-3 filled proportional counters being the most widely used because of their high detection efficiency and good gamma ray discrimination. However these counters have severe drawbacks in terms of detector size and scarcity of He-3. The aim of this work is to investigate an alternative neutron detection method by using a boron lining with existing NaI detectors and compare the results with those obtained from a He-3 detector. The results show a good sensitivity of the boron-lined NaI detector to neutrons at different source locations and a considerable improvement in efficiency compared to He-3 detectors. On top of this the NaI detectors are used to detect the gamma rays from the surrounding source and interacting media.
Resonant infrared detector with substantially unit quantum efficiency
NASA Technical Reports Server (NTRS)
Farhoomand, Jam (inventor); Mcmurray, Robert E., Jr. (inventor)
A resonant infrared detector includes an infrared-active layer which has first and second parallel faces and which absorbs radiation of a given wavelength. The detector also includes a first tuned reflective layer, disposed opposite the first face of the infrared-active layer, which reflects a specific portion of the radiation incident thereon and allows a specific portion of the incident radiation at the given wavelength to reach the infrared-active layer. A second reflective layer, disposed opposite the second face of the infrared-active layer, reflects back into the infrared-active layer substantially all of the radiation at the given wavelength which passes through the infrared-active layer. The reflective layers have the effect of increasing the quantum efficiency of the infrared detector relative to the quantum efficiency of the infrared-active layer alone.
Roadmap for high efficiency solid-state neutron detectors
NASA Astrophysics Data System (ADS)
Nikoli?, R. J.; Cheung, C. L.; Reinhardt, C. E.; Wang, T. F.
Solid-state thermal neutron detectors are generally fabricated in a planar configuration by coating a layer of neutron-to-alpha converter material onto a semiconductor. The as-created alpha particles in the material are expected to impinge the semiconductor and create electron-hole pairs which provide the electrical signal. These devices are limited in efficiency to a range near (2-5%)/cm2 due to the conflicting thickness requirements of the converter layer. In this case, the layer is required to be thick enough to capture the incoming neutron flux while at the same time adequately thin to allow the alpha particles to reach the semiconductor. A three dimensional matrix structure has great potential to satisfy these two requirements in one device. Such structures can be realized by using PIN diode pillar elements to extend in the third dimension with the converter material filling the rest of the matrix. Our strategy to fabricate this structure is based on both "top-down" and "bottom-up" approaches. The "top down" approach employs high-density plasma etching techniques, while the "bottom up" approach draws on the growth of nanowires by chemical vapor deposition. From our simulations for structures with pillar diameters from 2 micron down to 100 nm, the detector efficiency is expected to increase with a decrease in pillar size. Moreover, in the optimized configuration, the detector efficiency could be higher than 75%/cm2. Finally, the road map for the relationship between detector diameter and efficiency will be outlined.
Efficient filter for detecting gravitational wave bursts in interferometric detectors
Thierry Pradier; Nicolas Arnaud; Marie-Anne Bizouard; Fabien Cavalier; Michel Davier; Patrice Hello
Typical sources of gravitational wave bursts are supernovae, for which no accurate models exist. This calls for search methods with high efficiency and robustness to be used in the data analysis of foreseen interferometric detectors. A set of such filters is designed to detect gravitational wave burst signals. We first present filters based on the linear fit of whitened data
High collection efficiency CVD diamond alpha detectors
Bergonzo, P.; Foulon, F.; Marshall, R.D.; Jany, C.; Brambilla, A. [CEA/Saclay, Gif-sur-Yvette (France)] [CEA/Saclay, Gif-sur-Yvette (France); McKeag, R.D.; Jackman, R.B. [University College London (United Kingdom). Electronic and Electrical Engineering Dept.] [University College London (United Kingdom). Electronic and Electrical Engineering Dept.
Advances in Chemical Vapor Deposited (CVD) diamond have enabled the routine use of this material for sensor device fabrication, allowing exploitation of its unique combination of physical properties (low temperature susceptibility (> 500 C), high resistance to radiation damage (> 100 Mrad) and to corrosive media). A consequence of CVD diamond growth on silicon is the formation of polycrystalline films which has a profound influence on the physical and electronic properties with respect to those measured on monocrystalline diamond. The authors report the optimization of physical and geometrical device parameters for radiation detection in the counting mode. Sandwich and co-planar electrode geometries are tested and their performances evaluated with regard to the nature of the field profile and drift distances inherent in such devices. The carrier drift length before trapping was measured under alpha particles and values as high as 40% of the overall film thickness are reported. Further, by optimizing the device geometry, they show that a gain in collection efficiency, defined as the induced charge divided by the deposited charge within the material, can be achieved even though lower bias values are used.
Measurement of Compton scattering in phantoms by germanium detectors
Zasadny, K.R.; Koral, K.F. (Michigan Univ., Ann Arbor, MI (USA). Medical Center); Floyd, C.E. Jr.; Jaszczak, R.J. (Duke Univ., Durham, NC (USA). Dept. of Radiology)
Quantitative Anger-camera tomography requires correction for Compton scattering. The Anger camera spectral-fitting technique can measure scatter fractions at designated positions in an image allowing for correction. To permit verification of those measurements for {sup 131}I, the authors have determined scatter fractions with a high-purity germanium (HPGe) detector and various phantom configurations. The scatter fraction values for {sup 99m}Tc were also measured and are compared to results from Monte Carlo simulation. The phantom consisted of a 22.2 cm diameter {times} 18.6 cm high cylinder filled with water and a 6 cm diameter water-filled sphere placed at various locations inside the cylinder. Radioisotope is added to either the sphere or the cylinder. The source is collimated by an Anger camera collimator and the active area of the HPGe detector is defined by a 0.6 cm diameter hole in a lead shielding mask. Corrections include accounting for the HPGe detector efficiency as a function of gamma-ray energy, the finite energy resolution of detector and the HPGe detector energy resolution compared to that for a NaI(Tl) Anger camera.
Neutron efficiency of LaBr3:Ce detector
NASA Astrophysics Data System (ADS)
Ebran, A.; Roig, O.; M�ot, V.; Delaune, O.
We report on a measurement of the neutron detection efficiency in a LaBr3 detector in the energy range 0.1-2 MeV. The experiment was carried out using a 4 MV Van-de-Graaff accelerator which provided monoenergetic neutrons from T(p,n)3He and 7Li(p,n)7Be reactions. The five most intense ?-rays from the LaBr3(n, n ? ?) reaction have been studied to deduce the neutron sensitivity of the detector. GEANT4 simulations with different nuclear data libraries have been done and a comparison with the data is provided.
GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA
Winn, W.G.
The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or multiplet peak analysis, bypassing the usual peak fitting analysis for a differential f-function probability model. Because F is defined by the peak data, statistical limitations for peak fitting are avoided; however, the F-function does provide generic values for peak centroid, full width at half maximum, and tail that are consistent with a Gaussian formalism. GRABGAM has successfully analyzed over 10,000 customer samples, and it interfaces with a variety of supplementary codes for deriving detector efficiencies, backgrounds, and quality checks.
Investigation of the quantum efficiency of optical heterodyne detectors
NASA Technical Reports Server (NTRS)
Batchman, T. E.
The frequency response and quantum efficiency of optical photodetectors for heterodyne receivers is investigated. The measurements utilized two spectral lines from the output of two lasers as input to the photodetectors. These lines are easily measurable in power and frequency and hence serve as known inputs. By measuring the output current of the photodetector the quantum efficiency is determined as a function of frequency separation between the two input signals. An investigation of the theoretical basis and accuracy of this type of measurement relative to similar measurements utilizing risetime is undertaken. A theoretical study of the heterodyne process in photodetectors based on semiconductor physics is included so that higher bandwidth detectors may be designed. All measurements are made on commercially available detectors and manufacturers' specifications for normal photodetector operation are compared to the measured heterodyne characteristics.
Charge collection efficiency simulations of irradiated silicon strip detectors
NASA Astrophysics Data System (ADS)
Peltola, T.
During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face a more intense radiation environment than the present system was designed for. Thus, to upgrade the tracker to the required performance level, comprehensive measurements and simulation studies have already been carried out. Essential information of the performance of an irradiated silicon detector is obtained by monitoring its charge collection efficiency (CCE). From the evolution of CCE with fluence, it is possible to directly observe the effect of the radiation induced defects on the ability of the detector to collect charge carriers generated by traversing minimum ionizing particles (MIPs). In this paper the numerically simulated CCE and CCE loss between the strips of irradiated silicon strip detectors are presented. The simulations based on the Synopsys Sentaurus TCAD framework were performed before and after irradiation for fluences up to 1.5 � 1015 neqcm?2 for n-on-p sensors. A two level defect model and non-uniform three level defect model were applied for the proton irradiation simulations, and a two level model for neutrons. The results are presented together with the measurements of strip detectors irradiated by different particles and fluences and show considerable agreement for both CCE and its position dependency.
Charge Collection Efficiency Simulations of Irradiated Silicon Strip Detectors
T. Peltola
During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face more intense radiation environment than the present system was designed for. Thus, to upgrade the tracker to required performance level, comprehensive measurements and simulations studies have already been carried out. Essential information of the performance of an irradiated silicon detector is obtained by monitoring its charge collection efficiency (CCE). From the evolution of CCE with fluence, it is possible to directly observe the effect of the radiation induced defects to the ability of the detector to collect charge carriers generated by traversing minimum ionizing particles (mip). In this paper the numerically simulated CCE and CCE loss between the strips of irradiated silicon strip detectors are presented. The simulations based on Synopsys Sentaurus TCAD framework were performed before and after irradiation for fluences up to $1.5\\times10^{15}$ $\\textrm{n}_{\\textrm{eq}}$cm$^{-2}$ for the n-on-p sensors. A two level and non-uniform three level defect models were applied for the proton irradiation simulations and two level model for neutrons. The results are presented together with the measurements of strip detectors irradiated by different particles and fluences and show considerable agreement for both CCE and its position dependency.
Data encoding efficiency in binary strip detector readout
Garcia-Sciveres, Maurice
An analysis of the minimum number of bits needed for binary strip detector readout is presented. This enables a definition of data transmission efficiency relative to this theoretical minimum number of bits. Different level efficiencies are defined to include engineering properties needed for reliable transmission, such as DC-balance, and context information. Commonly used encoding methods are found to be inefficient. A new encoding method called Pattern Overlay Compression is introduced, which significantly outperforms current methods in the low occupancy range of interest.
The GMRF detector for hyperspectral imagery: An efficient fully-adaptive maximum likelihood detector
NASA Astrophysics Data System (ADS)
Schweizer, Susan Marie
Hyperspectral sensors collect hundreds of narrow and contiguously spaced spectral bands of data organized in the so called hyperspectral cube. The hyperspectral imagery provides fully registered spatial and high resolution spectral information that is invaluable in discriminating between man-made objects and natural clutter backgrounds, since the objects and clutter have unique spectral signatures that are captured by the data. This comes at a cost. The high volume of data in the hyperspectral cube and the associated processing that is required, has precluded the development of computationally practical Maximum-Likelihood (ML) detectors of man-made anomalies in clutter. This thesis solves this problem. We derive the Gauss- Markov random field (GMRF) detector, a computationally efficient ML anomaly detector that fully adapts to the unknown statistics of the clutter, and fully exploits the spatial and spectral correlation of the hyperspectral imagery. We test extensively our clutter adaptive GMRF detector with real imagery from several hyperspectral sensors. Our results show that the GMRF detector is significantly simpler computationally and noticeably improves the detection performance over the benchmark anomaly detection algorithm. Our approach avoids the costly step of inverting the large sample covariance matrix of the clutter. We parameterize directly the inverse of the clutter covariance and develop several alternative methods to match this inverse to the actual clutter statistics.
Highly Efficient Quantum Key Distribution Immune to All Detector Attacks
Wen-Fei Cao; Yi-Zheng Zhen; Yu-Lin Zheng; Zeng-Bing Chen; Nai-Le Liu; Kai Chen; Jian-Wei Pan
Vulnerabilities and imperfections of single-photon detectors have been shown to compromise security for quantum key distribution (QKD). The measurement-device-independent QKD (MDI-QKD) appears to be the most appealing solution to solve the issues. However, in practice one faces severe obstacles of having significantly lower key generation rate, difficult two photon interferences, and remote synchronization etc. In this letter, we propose a highly efficient and simple quantum key distribution scheme to remove all of these drawbacks. Our proposal can be implemented with only small modifications over the standard decoy BB84 system. Remarkably it enjoys both the advantages of high key generation rate (being almost two orders of magnitude higher than that based on conventional MDI-QKD) comparable to the normal decoy system, and security against any detector side channel attacks. Most favorably one can achieve complete Bell state measurements with resort to single photon interference, which reduces significantly experimental costs. Our approach enables utilization of high speed and efficient secure communication, particularly in real-life scenario of both metropolitan and intercity QKD network, with an attack free fashion from arbitrary detector side channels.
High-resolution study of the {sup 12}C({gamma},p{gamma}{sup '}){sup 11}B reaction using a HpGe detector to resolve excited states of {sup 11}B through the observation of their {gamma}-ray decays
Morrow, S.A.; Branford, D.; Foehl, K. [School of Physics, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); McGeorge, J.C.; MacGregor, I.J.D. [Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Adler, J.-O.; Hansen, K.; Isaksson, L.; Lundin, M.; Schroder, B. [Department of Nuclear Physics, University of Lund, S-223 62 Lund (Sweden)
Relative populations of states in {sup 11}B following the {sup 12}C({gamma},p){sup 11}B reaction have been measured with high resolution using a 70% HpGe {gamma} detector to observe decay {gamma} rays from the residual nucleus. The triplet of states near 7 MeV in {sup 11}B are resolved and the measured populations compared to previous data. The analysis includes a consideration of {gamma}-proton angular correlations, which was not made in the previous measurement. The new and previous results corrected for angular correlation effects agree reasonably well with calculations that include one- and two-body nuclear currents, pion exchange, and {delta} currents, under the assumption that the photons are mainly absorbed on exchanged pions.
Optimization of efficiency and response time of diffusion-based nuclear radiation detectors
S. E. Wouters; T. Otaredian; E. M. Schooneveld
The charge collection process in a diffusion-based silicon nuclear radiation detector was investigated by illuminating the detector at the backside with optical radiation. The results are compared to calculations and show good agreement. The collection mechanism is characterized, and the detector response to nuclear radiation and its optimum with respect to efficiency and response time are calculated. Efficiency and response
Efficiency and Noise Measurements of Nonuniformly Irradiated Doublesided Silicon Strip Detectors
California at Santa Cruz, University of
and the noise occupancy of double�sided silicon strip detectors, which were subjected to non�uniform proton at the high radiation end. We determined the efficiency and noise occupancy on both n�side and p�side in a 106 of the detectors. We have now made measurements of the efficiency and noise occupancy of irradiated detectors
Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector.
Renema, J J; Wang, Q; Gaudio, R; Komen, I; Op 't Hoog, K; Sahin, D; Schilling, A; van Exter, M P; Fiore, A; Engel, A; de Dood, M J A
We probe the local detection efficiency in a nanowire superconducting single-photon detector along the cross-section of the wire with a far subwavelength resolution. We experimentally find a strong variation in the local detection efficiency of the device. We demonstrate that this effect explains previously observed variations in NbN detector efficiency as a function of device geometry. PMID:26087352
Normalization in 3D PET: Comparison of Detector Efficiencies Obtained from Uniform Planar and Cylindrical Sources
Oakes, Terry
to the sinogram data, yielding axial uniformity indices of 0.78% (2D), 1.71% (3D planar), and 3.40% (3D cylinder to calculating the detector efficiencies was found to slightly improve axial uniformity and to slightly degrade-source is scanned to determine the individual detector efficiency factors () by creating a three-dimensional fan
Study of the charge collection efficiency of CdZnTe radiation detectors
Y. Nemirovsky; A. Ruzin; G. Asa; J. Gorelik
The charge collection efficiency of CdZnTe radiation detectors with two different configurations: aSchottky diode detector and aresistive detector are compared. The average charge collection efficiencies for three different directions of irradiation (negative electrode,\\u000a positive electrode and perpendicular to the electric field) are calculated. The mobility-lifetime product of the CdZnTe substrates\\u000a is evaluated from the dependence of the measured spectra upon
Validation of efficiency transfer for Marinelli geometries.
Ferreux, Laurent; Pierre, Sylvie; Thanh, Tran Thien; L�py, Marie-Christine
In the framework of environmental measurements by gamma-ray spectrometry, some laboratories need to characterize samples in geometries for which a calibration is not directly available. A possibility is to use an efficiency transfer code, e.g., ETNA. However, validation for large volume sources, such as Marinelli geometries, is needed. With this aim in mind, ETNA is compared, initially to a Monte Carlo simulation (PENELOPE) and subsequently to experimental data obtained with a high-purity germanium detector (HPGe). PMID:23623315
Efficiency of antiscatter grids for flat-detector CT
NASA Astrophysics Data System (ADS)
Kyriakou, Yiannis; Kalender, Willi
Flat-panel detector CT (FD-CT) scanners offer large volume coverage, but as a consequence are more susceptible to scatter artifacts than standard clinical CT scanners with smaller cone angles. FD-CT scanners can employ antiscatter grids as a scatter rejection technique. We evaluated three standard fluoroscopic antiscatter grids for two different field sizes with respect to scatter suppression efficiency and image quality improvement. The evaluations included simulations and measurements. Regarding the simulation a hybrid model combining deterministic and Monte Carlo (MC) calculations was used combined with an analytical calculation of grid transmission. The scatter-to-primary ratio (SPR) was measured using an adapted collimator technique in order to validate our simulations. The SPR obtained by simulations and measurements with and without antiscatter grids were in agreement typically within 10%. The employment of a grid does not generally provide a significant improvement of the signal-to-noise ratio (SNR). Antiscatter grids led to a significant reduction of cupping artifacts in all cases. There is a trade-off between the SNR and the reduction of the scatter intensity described by the signal-to-noise improvement factor (SNRif). For low- or medium-scatter conditions the increase in noise caused by the reduced primary transmission through the grid has to be compensated by a higher exposure. For high scatter conditions SNRif is significantly greater than 1; i.e. a decrease of dose of up to 50% can be reached.
Measurement of InGaAs single photon detector quantum efficiency at 1550nm
NASA Astrophysics Data System (ADS)
Zhao, Kun; Liu, Changming; Chen, Haidong; Shi, Xueshun
Single photon detectors nowadays are widely used in numerous applications such as quantum cryptography, laser ranging, single molecule spectroscopy and so on. And the calibration of the detection efficiency is quite important for some of the applications. In recent years, researchers find that correlated photon pairs can be employed to calibrate the detection efficiency of single-photon detectors with quite high precision. Firstly, we calibrated the InGaAs single photon detector quantum efficiency at 1550nm by correlated photon pairs. Consistency between the measurement result using correlated photon pairs and the reference value is better than 0.8%. Secondly, the detectors are calibrated with an attenuated laser source. Thirdly, the two methods for measuring the quantum efficiency of single photon detectors, correlated photon pairs and laser attenuation, respectively, are discussed and analyzed in detail. Finally, results derived from the two methods have been compared with each other.
Development of A Self Biased High Efficiency Solid-State Neutron Detector for MPACT Applications
Danon, Yaron; Bhat, Ishwara; Jian-Qiang Lu, James
Neutron detection is an important aspect of materials protection, accounting, and control for transmutation (MPACT). Currently He-3 filled thermal neutron detectors are utilized in many applications; these detectors require high-voltage bias for operation, which complicates the system when multiple detectors are used. In addition, due to recent increase in homeland security activity and the nuclear renaissance, there is a shortage of He-3, and these detectors become more expensive. Instead, cheap solid-state detectors that can be mass produced like any other computer chips will be developed. The new detector does not require a bias for operation, has low gamma sensitivity, and a fast response. The detection system is based on a honeycomb-like silicon device, which is filled with B-10 as the neutron converter; while a silicon p-n diode (i.e., solar cell type device) formed on the thin silicon wall of the honeycomb structure detects the energetic charged particles emitted from the B-10 conversion layer. Such a detector has ~40% calculated thermal neutron detection efficiency with an overall detector thickness of about 200 ?m. Stacking of these devices allows over 90% thermal neutron detection efficiency. The goal of the proposed research is to develop a high-efficiency, low-noise, self-powered solid-state neutron detector system based on the promising results of the existing research program. A prototype of this solid-state neutron detector system with sufficient detector size (up to 8-inch diam., but still portable and inexpensive) and integrated with interface electronics (e.g., preamplifier) will be designed, fabricated, and tested as a coincidence counter for MPACT applications. All fabrications proposed are based on silicon-compatible processing; thus, an extremely cheap detector system could be massively produced like any other silicon chips. Such detectors will revolutionize current neutron detection systems by providing a solid-state alternative to traditional gas-based neutron detectors.
Monte Carlo simulations of the response of a plastic scintillator and an HPGe spectrometer in coincidence.
Jokovi?, D R; Dragi?, A; Udovici?, V; Banjanac, R; Puzovi?, J; Anicin, I
A simulation programme based on the Geant4 toolkit has been developed to simulate the coincident responses of a plastic scintillator and an HPGe detector to the cosmic-ray muons. The detectors are situated in a low-level underground laboratory (25 m.w.e). Primary positions, momentum directions and energies of the muons are sampled from the angular and energy distributions of the cosmic-ray muons at the shallow underground level. Obtained coincident spectra of both detectors are presented and discussed. PMID:19231223
Experimental determination of LR115 detector efficiency for exposure to alpha particles
D Marocco; F Bochicchio
The alpha particle detection efficiency of LR-115 detectors has been measured against alpha particle energy E and incidence angle ? (with respect to the normal to the detector surface), using an experimental apparatus with an 241Am alpha source and air in a pressure-controlled chamber as the degrading medium, and a spark-counter for counting tracks. About 200 LR-115 detectors were exposed
Efficiently Coupling Light to Superconducting Nanowire Single-Photon Detectors
Hu, Xiaolong
We designed superconducting nanowire single-photon detectors (SNSPDs) integrated with silver optical antennae for free-space coupling and a dielectric waveguide for fiber coupling. According to our finite-element simulation, ...
Approximated total and full energy peak intrinsic efficiencies of gamma detectors for measuring systems design
B. Shapiro; A. Notea
Functions characterizing the performance of gauges based on gamma radiation correlate the design parameters and the variables to be measured. The radiation detector is a major component of the gauge. Analytic expressions for the total and full energy peak efficiencies were derived using the mean chord length in the detector's sensitive volume. The errors associated with this approximation were estimated
Absolute efficiency estimation of photon-number-resolving detectors using twin beams
Worsley, A P; Lundeen, J S; Mosley, P J; Smith, B J; Puentes, G; Thomas-Peter, N; Walmsley, I A; 10.1364/OE.17.004397
A nonclassical light source is used to demonstrate experimentally the absolute efficiency calibration of a photon-number-resolving detector. The photon-pair detector calibration method developed by Klyshko for single-photon detectors is generalized to take advantage of the higher dynamic range and additional information provided by photon-number-resolving detectors. This enables the use of brighter twin-beam sources including amplified pulse pumped sources, which increases the relevant signal and provides measurement redundancy, making the calibration more robust.
Absolute and angular efficiencies of a microchannel-plate position-sensitive detector
NASA Technical Reports Server (NTRS)
Gao, R. S.; Gibner, P. S.; Newman, J. H.; Smith, K. A.; Stebbings, R. F.
This paper presents a characterization of a commercially available position-sensitive detector of energetic ions and neutrals. The detector consists of two microchannel plates followed by a resistive position-encoding anode. The work includes measurement of absolute efficiencies of H(+), He(+), and O(+) ions in the energy range between 250 and 5000 eV, measurement of relative detection efficiencies as a function of particle impact angle, and a simple method for accurate measurement of the time at which a particle strikes the detector.
High quantum-efficiency photon-number-resolving detector for photonic on-chip information processing
Calkins, Brice; Lita, Adriana E; Metcalf, Benjamin J; Kolthammer, W Steven; Linares, Antia Lamas; Spring, Justin B; Humphreys, Peter C; Mirin, Richard P; Gates, James C; Smith, Peter G R; Walmsley, Ian A; Gerrits, Thomas; Nam, Sae Woo
The integrated optical circuit is a promising architecture for the realization of complex quantum optical states and information networks. One element that is required for many of these applications is a high-efficiency photon detector capable of photon-number discrimination. We present an integrated photonic system in the telecom band at 1550 nm based on UV-written silica-on-silicon waveguides and modified transition-edge sensors capable of number resolution and over 40% efficiency. Exploiting the mode transmission failure of these devices, we multiplex three detectors in series to demonstrate a combined 79% +/- 2% detection efficiency with a single pass, and 88% +/- 3% at the operating wavelength of an on-chip terminal reflection grating. Furthermore, our optical measurements clearly demonstrate no significant unexplained loss in this system due to scattering or reflections. This waveguide and detector design therefore allows the placement of number-resolving single-photon detectors of predictable efficienc...
Note: Fast neutron efficiency in CR-39 nuclear track detectors
NASA Astrophysics Data System (ADS)
Cavallaro, S.
CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.
Investigation of efficient termination structure for improved breakdown properties of semiconductor radiation detectors
D. Krizaj; D. Resnik; D. Vrtacnik; S. Amon; V. Cindro
Efficiency of a new junction termination structure for improvement of breakdown properties of semiconductor radiation detectors is investigated. The structure consists of a diffused resistor winding around the active junction in a spiral fashion. The current flow through the spiral enables controlled potential distribution along the spiral turns and thus controlled depletion spreading from the main junction, efficiently preventing premature
Correlation of the charge collection efficiency of GaAs particle detectors with material properties
K Berwick; M. R Brozel; C. M Buttar; J. S Pooni; P. J Sellin; S. M Young
Measurements of the Charge Collection Efficiency (CCE) of radiation detectors fabricated from semi-insulating GaAs wafers which have different thermal histories have been undertaken. A correlation between charge collection efficiency and electrical resistivity has been observed. These are consistent with a dominant dependence of CCE with the concentration of the ionized deep donor, EL2+.
Developing 152Eu into a standard for detector efficiency calibration
Ruy M. Castro; Vito R. Vanin; Paulo R. Pascholati; Nora L. Maidana; Mauro S. Dias; Marina F. Koskinas
A ?�? coincidence experiment was performed to check the 152Eu 13-year decay scheme and the placement of the observed ?-ray transitions. The multi-detector array for residual activity measurement of the Linear Accelerator Laboratory was used. The source activity was 1MBq, and about 109 coincidence events were observed. About 30 ?'s were placed in the decay scheme and four 152Sm levels
Quantum efficiency test set up performances for NIR detector characterization at ESTEC
NASA Astrophysics Data System (ADS)
Crouzet, P.-E.; Duvet, L.; De Wit, F.; Beaufort, T.; Blommaert, S.; Butler, B.; Van Duinkerken, G.; ter Haar, J.; Heijnen, J.; van der Luijt, K.; Smit, H.; Viale, T.
The Payload Technology Validation Section (Future mission preparation Office) at ESTEC is in charge of specific mission oriented validation activities, for science and robotic exploration missions, aiming at reducing development risks in the implementation phase. These activities take place during the early mission phases or during the implementation itself. In this framework, a test set up to characterize the quantum efficiency of near infrared detectors has been developed. The first detector to be tested will an HAWAII-2RG detector with a 2.5?m cut off, it will be used as commissioning device in preparation to the tests of prototypes European detectors developed under ESA funding. The capability to compare on the same setup detectors from different manufacturers will be a unique asset for the future mission preparation office. This publication presents the performances of the quantum efficiency test bench to prepare measurements on the HAWAII-2RG detector. A SOFRADIR Saturn detector has been used as a preliminary test vehicle for the bench. A test set up with a lamp, chopper, monochromator, pinhole and off axis mirrors allows to create a spot of 1mm diameter between 700nm and 2.5?m.The shape of the beam has been measured to match the rms voltage read by the Merlin Lock -in amplifier and the amplitude of the incoming signal. The reference detectors have been inter-calibrated with an uncertainty up to 3 %. For the measurement with HAWAII-2RG detector, the existing cryostat [1] has been modified to adapt cold black baffling, a cold filter wheel and a sapphire window. An statistic uncertainty of +/-2.6% on the quantum efficiency on the detector under test measurement is expected.
Substrate characterization for underwater gamma spectrometry: tank measurement results utilizing efficiencies calculated via Monte-Carlo code
R. Ocone; A. Kostezh; V. Kurinenko; A. Tyshchenko; G. Derkach; P. Leone
In order to study the sediment contamination, underwater gamma-ray spectrometry measurements performed by the sub-marine detector Canberra HpGe with a relative efficiency of 80% were carried out in an equipped tank at the Ukrainian Hydrometeorological Institute of Kiev. Different substrates, certified sources and experiment geometrical set-up were arranged. Efficiencies were calculated by in situ object counting system (ISOCS) software. ISOCS
Investigations of 2? decay measured by low background HPGe spectrometer OBELIX
Rukhadze, Ekaterina [Institute of Experimental and Applied Physics, CTU in Prague, Horska 3a/22, 128 00 Prague 2 (Czech Republic); Collaboration: OBELIX Collaboration; SuperNEMO Collaboration
A low background high sensitive HPGe spectrometer OBELIX was installed at the Modane Underground Laboratory (LSM, France, 4800 m w.e.). The detector was designed to measure a contamination of enriched isotopes and radio-impurities in construction materials, to investigate rare nuclear processes such as resonance neutrinoless double electron capture and two-neutrino double beta decay to excited states of daughter nuclei. Spectrometer sensitivity, contamination of NEMO-3 sources and results of 2?2?{sup ?} decay of {sup 100}Mo to the 0{sup +} (1130 keV) and 2{sup +} (540 keV) excited states as well as future plans for OBELIX detector are given.
Aguayo Navarrete, Estanislao; Fast, James E.; Reid, Douglas J.
ABSTRACT A two-phase nitrogen thermosiphon was developed for the new generation of low-background high-purity germanium (HPGe) arrays. The cooling system for these arrays has to be able to handle the heat load (>20 W) presented by a large detector mass while meeting stringent requirements necessary for low-background systems. The HPGe detector modules should operate as close to liquid nitrogen temperature (<80K) as possible to provide adequate operating conditions for a full range of HPGe impurity concentrations. In addition, exceptional temperature stability (<1 K) is needed to reduce electronic gain shifts due to changes in the front-end electronics operating temperature. In order to meet the background requirements of state-of-the-art systems these arrays are enclosed in passive lead and copper shielding up to 1 m thick. In this paper we present a cooling system for low-background experiments that complies with these stringent geometrical restrictions. Active cooling was integrated via a horizontal thermosiphon that can be fabricated using ultra-pure electroformed copper. It was charged with nitrogen to 434 kPa (63 PSIA) at 292 K, which provided a fill ratio of 10%. The results showed that the thermosiphon can effectively remove in excess of 25 W of heat load.
Note: fast neutron efficiency in CR-39 nuclear track detectors.
Cavallaro, S
CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed. PMID:25832287
Evaluation of efficiency calibration parameters of the LR-115 radon detector.
Mireles, F; D�vila, J I; Garc�a, M L; Pinedo, J L; L�pez, H
Measurement of 222Rn is an important research concern because of the high-energy alpha emission of its 218Po and 214Po progeny. The LR-115 passive detector is the basis of a solid-state nuclear track detector (SSNTD) whose use for radon measurements has been well established. The usage of the SSNTD technique requires calibration by comparison. The aim of this work is to evaluate the efficiency calibration parameters for the radon measurement system that three steps: (1) irradiation conditions, (2) etching conditions, and (3) track counting. The following parameters were evaluated: breakdown and counting voltages for the spark counter, detector thickness, etching time, temperature and NaOH concentration as etching conditions for the LR-115 detector. Calibrating factors of 0.035 and 0.028 tracks cm-2 Bq-1 m3 d-1 for the open- and closed-chamber radon monitors, respectively, were determined considering the best efficiency calibration parameter values. PMID:20386194
Developing 152Eu into a standard for detector efficiency calibration.
Castro, Ruy M; Vanin, Vito R; Pascholati, Paulo R; Maidana, Nora L; Dias, Mauro S; Koskinas, Marina F
A gamma-gamma coincidence experiment was performed to check the 152Eu 13-year decay scheme and the placement of the observed gamma-ray transitions. The multi-detector array for residual activity measurement of the Linear Accelerator Laboratory was used. The source activity was 1 MBq, and about 10(9) coincidence events were observed. About 30 gamma's were placed in the decay scheme and four 152Sm levels were added to the previously known set of levels fed in 152Eu 13-year decay. PMID:14987655
Charge collection efficiency of an irradiated cryogenic double-p silicon detector
K. Borer; S. Janos; Z. Li; B. Dezillie; C. Da Vi�; V. Granata; L. Casagrande; R. W. I. de Boer; C. Louren�o; T. O. Niinikoski; V. G. Palmieri; S. Chapuy; Z. Dimcovski; E. Grigoriev; W. Bell; S. R. H. Devine; G. Ruggiero; V. O�Shea; K. Smith; P. Berglund; W. de Boer; F. Hauler; S. Heising; L. Jungermann; M. Abreu; P. Rato; P. Sousa; V. Cindro; M. Mikuz; M. Zavrtanik; A. Esposito; S. Paul; S. Buontempo; N. D�Ambrosio; S. Pagano; V. Eremin; E. Verbitskaya
We present results on the measurement of the charge collection efficiency of a p+\\/n\\/p+ silicon detector irradiated to 1�1015n\\/cm2, operated in the temperature range between 80 and 200K. For comparison, measurements obtained with a standard silicon diode (p+\\/n\\/n+), irradiated to the same fluence, are also presented. Both detectors show a dramatic increase of the CCE when operated at temperatures around
Charge collection efficiency of irradiated silicon detector operated at cryogenic temperatures
K. Borer; S. Janos; V. G. Palmieri; B. Dezillie; Z. Li; P. Collins; T. O. Niinikoski; C. Louren�o; P. Sonderegger; E. Borchi; M. Bruzzi; S. Pirollo; V. Granata; S. Pagano; S. Chapuy; Z. Dimcovski; E. Grigoriev; W. Bell; S. R. H. Devine; V. O'Shea; K. Smith; P. Berglund; W. de Boer; F. Hauler; S. Heising; L. Jungermann; L. Casagrande; V. Cindro; M. Mikuz; M. Zavartanik; C. da Vi�; A. Esposito; I. Konorov; S. Paul; L. Schmitt; S. Buontempo; N. D'Ambrosio; G. Ruggiero; V. Eremin; E. Verbitskaya
The charge collection efficiency (CCE) of heavily irradiated silicon diode detectors was investigated at temperatures between 77 and 200K. The CCE was found to depend on the radiation dose, bias voltage value and history, temperature, and bias current generated by light. The detector irradiated to the highest fluence 2�1015n\\/cm2 yields a MIP signal of at least 15000e? both at 250V
Charge collection efficiency of irradiated silicon detectors operated at cryogenic temperatures
K. Borer; S. Janos; V. G. Palmieria; B Dezillie; Z Li; P Collins; T O Niinikoski; C Louren�o; P Sonderegger; E Borchi; Mara Bruzzi; S Pirollo; V Granata; S Pagano; S Chapuy; Zlatomir Dimcovski; E Grigoriev; W Bell; S R H Devine; V O'Shea; K Smith; P Berglund; Wim de Boer; F Hauler; S Heising; L Jungermann; L Casagrande; V Cindro; M Mikuz; M Zavrtanik; C Da Vi�; A P Esposito; I Konorov; S Paul; L Schmitt; S Buontempo; N D'Ambrosio; G Ruggiero; V V Eremin; E Verbitskaya
The charge collection efficiency (CCE) of heavily irradiated silicon diode detectors was investigated at temperatures between 77 and 200 K. The CCE was found to depend on the radiation dose, bias voltage value and history, temperature, and bias current generated by light. The detector irradiated to the highest fluence 2�1015 n\\/cm2 yields a MIP signal of at least 15000 e-
Practical attacks on decoy-state quantum-key-distribution systems with detector efficiency mismatch
NASA Astrophysics Data System (ADS)
Fei, Yangyang; Gao, Ming; Wang, Weilong; Li, Chaobo; Ma, Zhi
To the active-basis-choice decoy-state quantum-key-distribution systems with detector efficiency mismatch, we present a modified attack strategy, which is based on the faked states attack, with quantum nondemolition measurement ability to restress the threat of detector efficiency mismatch. Considering that perfect quantum nondemolition measurement ability doesn't exist in real life, we also propose a practical attack strategy using photon number resolving detectors. Theoretical analysis and numerical simulation results show that, without changing the channel, our attack strategies are serious threats to decoy-state quantum-key-distribution systems. The eavesdropper may get some information about the secret key without causing any alarms. Besides, the lower bound of detector efficiency mismatch to run our modified faked states attack successfully with perfect quantum nondemolition measurement ability is also given out, which provides the producers of quantum-key-distribution systems with a reference and can be treated as the approximate secure bound of detector efficiency mismatch in decoy-state quantum-key-distribution systems.
Absolute detector quantum-efficiency measurements using correlated photons
A. L. Migdall; R. U. Datla; A. Sergienko; J. S. Orszak; Y. H. Shih
An experimental system using correlated photons for radiometric purposes has been set up at the National Institute of Standards and Technology (NIST). We use pairs of correlated photons to produce spatial maps of the absolute efficiency of a photomultiplier photocathode at four wavelengths. We also compare this technique with measurements carried out by conventional means tied to existing radiometric standards.
Coincidence summing corrections for a clover detector
NASA Astrophysics Data System (ADS)
Agarwal, Chhavi; Danu, L. S.; Gathibandhe, M.; Goswami, A.; Biswas, D. C.
The true coincidence summing effect on the full energy peak efficiency calibration of a clover HPGe detector for point sources has been determined as a function of sample-to-detector distance using mono-energetic and multi-energetic gamma ray sources. The coincidence summing effect has been observed to increase at closer distances with the correction factors as high as 1.25 at closest distance studied. The correction factors for the total and the photopeak efficiencies have been obtained using the analytical method. The clover detector response has been simulated using MCNP code, taking care of the bevels and the flat surfaces of the clover detector. The geometry of the clover detector has been optimized to match the experimental and the theoretical efficiencies. The true coincidence summing correction factors (kTCS) have also been experimentally obtained by taking the ratio of corresponding mono-energetic extrapolated efficiencies to multi-energetic efficiencies. The kTCS obtained from analytical method has been found to match with the experimental kTCS with the simulated values within 1-5%.
Relative efficiency of TL detectors to energetic ion beams
P. Bilski; M. Puchalska
The relative TL efficiency of LiF:Mg, Ti and LiF:Mg, Cu, P was evaluated for several ion beams, ranging from helium to xenon ions. Irradiations were realized at the HIMAC accelerator in Chiba, Japan, partly within the ICCHIBAN intercomparison project. The covered LET range was extending from about 2keV\\/?m to 1500keV\\/?m.Both tested TLD types exhibited a decrease of relative response with
Efficient modeling of Compton diode gamma radiation detectors
D. R. Drumm; J. J. Hohlfelder; J. D. Kotulski; G. J. Scrivner; G. S. Mills; T. J. Tanaka
The CEPXS\\/ONELD code package proves to be significantly more efficient than electron Monte Carlo for computing the spherical Compton diode response to gamma irradiation, requiring only minutes instead of hours of Cray computer time. The adjoint capability of CEPXS\\/ONELD allows the complete energy-angle response of a Compton diode to be determined with a single transport calculation. The method is a
Efficient modeling of Compton diode gamma radiation detectors
C. R. Drumm; J. J. Hohlfelder; J. D. Kotulski; G. J. Scrivner; G. S. MillsandT; T. J. Tanaka
The CEPXS\\/ONELD code package proved to be significantly more efficient than electron Monte Carlo for computing spherical Compton diode response to gamma irradiation. The authors review the mechanism responsible for the production of electric currents in Compton diodes, describe the calculation method, and present results for a few representative Compton diodes. The adjoint capability of CEPXS\\/ONELD allows the complete energy-angle
A simple approach to determine the radioactivities of nuclides with 200�2000�keV ? ray(s) in the absence of efficiency calibration standard
Xiao-Gui Feng; Qian-Ge He; Zhong-Gong Chen; Xue-Mei Han; Jian-Feng Guo
By combing 4? liquid scintillation (LS) and ? spectrometry, we proposed a new approach, which is based on the linearity of the energy and the efficiency of coaxial HPGe detectors in logarithmic coordinates, to determine the radioactivities of nuclides with 200�2000�keV ? ray(s). In this approach, the multi-gamma-ray nuclide 152Eu has been applied to obtain the slope of energy-efficiency line.
Monte-Carlo calculations of Ge detector escape-peak efficiencies
NASA Technical Reports Server (NTRS)
Owens, Alan; Gehrels, Neil; Pascarelle, Sebastian M.; Teegarden, Bonnard J.
The authors present calculated first and second escape peak efficiencies for a variety of n-type coaxial Ge detectors using the Monte Carlo method. The results are given for right-circular cylindrical geometries of size ranging from 3-cm diameter x 3-cm thick to 8-cm diameter x 8-cm thick. For completeness, the intrinsic interaction and photopeak efficiencies for energies ranging from 20 keV to 20 MeV are listed. The calculations have been tested against experimental measurement and found to be in agreement to within the quoted errors (typically 10 percent). It is found that the ratio of the second escape peak efficiency to the first escape peak efficiency, R, is approximately independent of energy for small detector volumes but has a weak power law energy dependence for large volumes. It is shown that R also varies as an inverse power law of the active volume.
Efficient modeling of compton diode gamma radiation detectors
Drumm, C.R.; Hohlfelder, J.J.; Kotulski, J.D.; Scrivner, G.L.; Mills, G.S.; Tanaka, T.J. (Sandia National Labs., Albuquerque, NM (United States))
This paper reports on the CEPXS/ONELD code package which proves to be significantly more efficient than electron Monte Carlo for computing spherical Compton diode response to gamma irradiation, requiring only minutes instead of hours of Cray computer time. The adjoint capability of CEPXS/ONELD allows the complete energy-angle response of a Compton diode to be determined with a single transport calculation. The method is a useful tool for determining new Compton-diode designs with desired energy-response characteristics.
Influence of electron traps on charge-collection efficiency in GaAs radiation detectors
F. Nava; C M Canali; A. Castaldini; A. Cavallini; S D D'Auria; C. del Papa; C. Frigeri; L. Zanotti; A. Cetronio; C. Lanzieri; Antonino Zichichi
This paper deals with the interpretation of the charge-collection efficiency for minimum ionizing particles in terms of electron traps in semi-insulating liquid encapsulated Czochralski gallium arsenide detectors fabricated with thicknesses of 80 mum, 200 mum, and 300 mum. The results, obtained within the context of the RD-8 project, show that low values of charge-collection efficiency cannot be ascribed primarily to
Accurate and Efficient Filtering for the Intel Thread Checker Race Detector
Torrellas, Josep
Accurate and Efficient Filtering for the Intel Thread Checker Race Detector Paul Sack firstname.lastname@example.com ABSTRACT Debugging data races in parallel applications is a difficult task. Error-causing data races may or not a debugger is used, and other effects. Further, many race conditions cause incorrect pro- gram behavior only
Charge collection efficiency in a semiconductor radiation detector with a non-constant electric field
K. S. Shah; J. C. Lund; F. Olschner
The development of a model which enables the calculation of charge collection efficiencies in a planar semiconductor detector with a nonconstant electric field is described. The validity of the model is verified analytically by comparing the results predicted by it with known solutions for the limiting case of a constant field. The correctness of the model is also established by
Evaluation of active layer properties and charge collection efficiency of GaAs particle detectors
J. W. Chen; T. Fr�mmichen; J. Ludwig; M. Kohler; T. Pl�tze; M. Rogalla; K. Runge; D. G. Ebling; M. Fiederle; P. Hug
According to Ramo's theorem the charge collection efficiency of a particle detector is mainly influenced by the field distribution between the contacts of a Schottky diode. In semi-insulating GaAs material a space charge layer is formed due to deep levels needed for the compensation of acceptors. In this paper the deep levels and their influence on the distribution of the
High quantum-efficiency photon-number-resolving detector for photonic on-chip information processing.
Calkins, Brice; Mennea, Paolo L; Lita, Adriana E; Metcalf, Benjamin J; Kolthammer, W Steven; Lamas-Linares, Antia; Spring, Justin B; Humphreys, Peter C; Mirin, Richard P; Gates, James C; Smith, Peter G R; Walmsley, Ian A; Gerrits, Thomas; Nam, Sae Woo
The integrated optical circuit is a promising architecture for the realization of complex quantum optical states and information networks. One element that is required for many of these applications is a high-efficiency photon detector capable of photon-number discrimination. We present an integrated photonic system in the telecom band at 1550 nm based on UV-written silica-on-silicon waveguides and modified transition-edge sensors capable of number resolution and over 40 % efficiency. Exploiting the mode transmission failure of these devices, we multiplex three detectors in series to demonstrate a combined 79 % � 2 % detection efficiency with a single pass, and 88 % � 3 % at the operating wavelength of an on-chip terminal reflection grating. Furthermore, our optical measurements clearly demonstrate no significant unexplained loss in this system due to scattering or reflections. This waveguide and detector design therefore allows the placement of number-resolving single-photon detectors of predictable efficiency at arbitrary locations within a photonic circuit - a capability that offers great potential for many quantum optical applications. PMID:24104153
Weakly ionizing charged particle detectors with high efficiency using transitory electronic secondary emission of porous CsI
NASA Astrophysics Data System (ADS)
Chianelli, C.; Ageron, P.; Bouvet, J. P.; Karolak, M.; Martin, S.; Robert, J. P.
A very high efficiency detector for weakly ionizing particles is described. This very thin detector (2 mg/cm 2), using the transitory electronic secondary emission of porous CsI, has allowed us to detect protons of 540 MeV energy with a detection efficiency ? ? 95% and a time resolution of 450 ps within the SATURNE synchrotron (CEN Saclay).
Weakly ionizing charged particle detectors with high efficiency using transitory electronic secondary emission of porous CsI
C. Chianelli; P. Ageron; J. P. Bouvet; M. Karolak; S. Martin; J. P. Robert
A very high efficiency detector for weakly ionizing particles is described. This very thin detector (2 mg\\/cm2), using the transitory electronic secondary emission of porous CsI, has allowed us to detect protons of 540 MeV energy with a detection efficiency eta >= 95% and a time resolution of 450 ps within the SATURNE synchrotron (CEN Saclay).
Waveguide integrated superconducting single-photon detectors with high internal quantum efficiency at telecom wavelengths.
Kahl, Oliver; Ferrari, Simone; Kovalyuk, Vadim; Goltsman, Gregory N; Korneev, Alexander; Pernice, Wolfram H P
Superconducting nanowire single-photon detectors (SNSPDs) provide high efficiency for detecting individual photons while keeping dark counts and timing jitter minimal. Besides superior detection performance over a broad optical bandwidth, compatibility with an integrated optical platform is a crucial requirement for applications in emerging quantum photonic technologies. Here we present SNSPDs embedded in nanophotonic integrated circuits which achieve internal quantum efficiencies close to unity at 1550?nm wavelength. This allows for the SNSPDs to be operated at bias currents far below the critical current where unwanted dark count events reach milli-Hz levels while on-chip detection efficiencies above 70% are maintained. The measured dark count rates correspond to noise-equivalent powers in the 10(-19)?W/Hz(-1/2) range and the timing jitter is as low as 35?ps. Our detectors are fully scalable and interface directly with waveguide-based optical platforms. PMID:26061283
Waveguide integrated superconducting single-photon detectors with high internal quantum efficiency at telecom wavelengths
Kahl, Oliver; Ferrari, Simone; Kovalyuk, Vadim; Goltsman, Gregory N.; Korneev, Alexander; Pernice, Wolfram H. P.
Superconducting nanowire single-photon detectors (SNSPDs) provide high efficiency for detecting individual photons while keeping dark counts and timing jitter minimal. Besides superior detection performance over a broad optical bandwidth, compatibility with an integrated optical platform is a crucial requirement for applications in emerging quantum photonic technologies. Here we present SNSPDs embedded in nanophotonic integrated circuits which achieve internal quantum efficiencies close to unity at 1550?nm wavelength. This allows for the SNSPDs to be operated at bias currents far below the critical current where unwanted dark count events reach milli-Hz levels while on-chip detection efficiencies above 70% are maintained. The measured dark count rates correspond to noise-equivalent powers in the 10?19?W/Hz?1/2 range and the timing jitter is as low as 35?ps. Our detectors are fully scalable and interface directly with waveguide-based optical platforms. PMID:26061283
High optical efficiency and photon noise limited sensitivity of microwave kinetic inductance detectors using phase readout
Janssen, R. M. J., E-mail: firstname.lastname@example.com; Endo, A. [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands)] [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands); Baselmans, J. J. A. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584CA Utrecht (Netherlands)] [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584CA Utrecht (Netherlands); Ferrari, L.; Yates, S. J. C. [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands)] [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands); Baryshev, A. M. [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands) [SRON Netherlands Institute for Space Research, Landleven 12, 9747AD Groningen (Netherlands); Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Klapwijk, T. M. [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands) [Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628CJ Delft (Netherlands); Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation)
We demonstrate photon noise limited performance in both phase and amplitude readout in microwave kinetic inductance detectors (MKIDs) consisting of NbTiN and Al, down to 100 fW of optical power. We simulate the far field beam pattern of the lens-antenna system used to couple radiation into the MKID and derive an aperture efficiency of 75%. This is close to the theoretical maximum of 80% for a single-moded detector. The beam patterns are verified by a detailed analysis of the optical coupling within our measurement setup.
High efficiency, large-active-area superconducting nanowire single-photon detectors
NASA Astrophysics Data System (ADS)
Gu, Min; Zhang, La-Bao; Kang, Lin; Zhao, Qing-Yuan; Jia, Tao; Wan, Chao; Xu, Rui-Ying; Yang, Xiao-Zhong; Wu, Pei-Heng; Zhang, Yong; Xia, Jin-Song
Niobium nitride superconducting nanowire single-photon detectors were fabricated on thermally oxidized silicon substrates with large active areas of 30 ?m � 30 ?m. To achieve non-constricted detectors, we improved the film growth and electron beam lithography process to fabricate uniform 100-nm wide NbN nanowires with a fill factor of 50%. The devices showed 72.4% system detection efficiency (SDE) at 100-Hz dark count rate (DCR) and 74-ps timing jitter, measured at the fiber communication wavelength of 1550 nm. The highest SDE which is 81.2% when the DCR is ?700 c/s appears at the wavelength of 1650 nm.
Monte Carlo study of a highly efficient gas ionization detector for megavoltage imaging and image-guided radiotherapy.
Keller, H; Glass, M; Hinderer, R; Ruchala, K; Jeraj, R; Olivera, G; Mackie, T Rock
The imaging characteristics of an arc-shaped xenon gas ionization chamber for the purpose of megavoltage CT imaging were investigated. The detector consists of several hundred 320 microm thick gas cavities separated by thin tungsten plates of the same thickness. Dose response, efficiency and resolution parameters were calculated using Monte Carlo simulations. The calculations were compared to measurements taken in a 4 MV photon beam, assuming that the measured signal in the chambers corresponds to the therein absorbed dose. The measured response profiles for narrow and broad incident photon beams could be well reproduced with the Monte Carlo calculations. They show, that the quantum efficiency is 29.2% and the detective quantum efficiency at zero frequency DQE(0) is 20.4% for the detector arc placed in focus with the photon source. For a detector placed out of focus, these numbers even increase. The efficiency of this kind of radiation detector for megavoltage radiation therefore surpasses the reported efficiency of existing detector technologies. The resolution of the detector is quantified with calculated and measured line spread functions. The corresponding modulation transfer functions were determined for different thicknesses of the tungsten plates. They show that the resolution is only slightly dependent on the plate thickness but is predominantly determined by the cell size of the detector. The optimal plate thickness is determined by a tradeoff between quantum efficiency, total signal generation and resolution. Thicker plates are more efficient but the total signal and the resolution decrease with plate thickness. In conclusion, a gas ionization chamber of the described type is a highly efficient megavoltage radiation detector, allowing to obtain CT images with very little dose for a sufficient image quality for anatomy verification. This kind of detector might serve as a model for a future generation of highly efficient radiation detectors. PMID:11865988
The effect of magnetic field on the intrinsic detection efficiency of superconducting single-photon detectors
Renema, J J; Komen, I; Wang, Q; Gaudio, R; Hoog, K P M op 't; Zhou, Z; Sahin, D; Fiore, A; Kes, P; Aarts, J; van Exter, M P; de Dood, M J A; Driessen, E F C
We experimentally investigate the effect of a magnetic field on photon detection in superconducting single-photon detectors. At low fields, the effect of a magnetic field is through the direct modification of the quasiparticle density of states of the superconductor, and magnetic field and bias current are interchangable, as is expected for homogeneous dirty-limit superconductors. At the field where a first vortex enters the detector, the effect of the magnetic field is reduced, up until the point where the critical current of the detector starts to be determined by flux flow. From this field on, increasing the magnetic field does not alter the detection of photons anymore, whereas it does still change the rate of dark counts. This result points at an intrinsic difference in dark and light counts, and also shows that no enhancement of the intrinsic detection efficiency of a straight SSPD wire is achievable in a magnetic field.
The effect of magnetic field on the intrinsic detection efficiency of superconducting single-photon detectors
NASA Astrophysics Data System (ADS)
Renema, J. J.; Rengelink, R. J.; Komen, I.; Wang, Q.; Gaudio, R.; op't Hoog, K. P. M.; Zhou, Z.; Sahin, D.; Fiore, A.; Kes, P.; Aarts, J.; van Exter, M. P.; de Dood, M. J. A.; Driessen, E. F. C.
We experimentally investigate the effect of a magnetic field on photon detection in superconducting single-photon detectors (SSPDs). At low fields, the effect of a magnetic field is through the direct modification of the quasiparticle density of states of the superconductor, and magnetic field and bias current are interchangeable, as is expected for homogeneous dirty-limit superconductors. At the field where a first vortex enters the detector, the effect of the magnetic field is reduced, up until the point where the critical current of the detector starts to be determined by flux flow. From this field on, increasing the magnetic field does not alter the detection of photons anymore, whereas it does still change the rate of dark counts. This result points at an intrinsic difference in dark and photon counts, and also shows that no enhancement of the intrinsic detection efficiency of a straight SSPD wire is achievable in a magnetic field.
An efficient, movable single-particle detector for use in cryogenic ultra-high vacuum environments.
Spruck, Kaija; Becker, Arno; Fellenberger, Florian; Grieser, Manfred; von Hahn, Robert; Klinkhamer, Vincent; Novotn�, Old?ich; Schippers, Stefan; Vogel, Stephen; Wolf, Andreas; Krantz, Claude
A compact, highly efficient single-particle counting detector for ions of keV/u kinetic energy, movable by a long-stroke mechanical translation stage, has been developed at the Max-Planck-Institut f�r Kernphysik (Max Planck Institute for Nuclear Physics, MPIK). Both, detector and translation mechanics, can operate at ambient temperatures down to ?10 K and consist fully of ultra-high vacuum compatible, high-temperature bakeable, and non-magnetic materials. The set-up is designed to meet the technical demands of MPIK's Cryogenic Storage Ring. We present a series of functional tests that demonstrate full suitability for this application and characterise the set-up with regard to its particle detection efficiency. PMID:25725832
Intrinsic detection efficiency of superconducting nanowire single-photon detectors with different thicknesses
NASA Astrophysics Data System (ADS)
Hofherr, M.; Rall, D.; Ilin, K.; Siegel, M.; Semenov, A.; H�bers, H.-W.; Gippius, N. A.
We evaluate experimentally the intrinsic detection efficiency (IDE) of superconducting NbN nanowire single-photon detectors in the range of wire thicknesses from 4 to 12 nm. The study is performed in the broad spectral interval between near-ultraviolet (wavelength 400 nm) and near-infrared (wavelength 2000 nm) light with plane waves at normal incidence. For visible light the IDE of the thinnest detectors reaches 70%. We use numerically computed absorptance of the nanowire-structures for the analysis of the experimental data. Variations in the detection efficiency with both the wire thickness and the wavelength evidence the red boundary of the hot-spot photon-detection mechanism. We explain the detection at larger wavelengths invoking thermal excitation of magnetic Pearl vortices over the potential barrier at the edges of the wire.
Development of practical superconducting nanowire single photon detector system with high detection efficiency
Shigehito Miki; Taro Yamashita; Hirotaka Terai; Mikio Fujiwara; Masahide Sasaki; Zhen Wang
We have developed a practical superconducting nanowire single photon detector (SNSPD) system with our superconducting thin films and devices fabrication, optical coupling packaging, and cryogenic technology. The SNSPD devices were fabricated from high-quality niobium nitride (NbN) ultra-thin films that were epitaxially grown on single-crystal MgO substrates, and optical cavity structure were applied for improvement of photo absorption efficiency. The SNSPD
A new measurement of the neutron detection efficiency for the NaI Crystal Ball detector
NASA Astrophysics Data System (ADS)
Martemianov, M.; Kulikov, V.; Demissie, B. T.; Marinides, Z.; Akondi, C. S.; Annand, J. R. M.; Arends, H. J.; Beck, R.; Borisov, N.; Braghieri, A.; Briscoe, W. J.; Cherepnya, S.; Collicott, C.; Costanza, S.; Downie, E. J.; Dieterle, M.; Ferretti Bondy, M. I.; Fil'kov, L. V.; Garni, S.; Glazier, D. I.; Glowa, D.; Gradl, W.; Gurevich, G.; Hornidge, D.; Huber, G. M.; Kaeser, A.; Kashevarov, V. L.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Krusche, B.; Lazarev, A.; Linturi, J. M.; Lisin, V.; Livingston, K.; MacGregor, I. J. D.; Manley, D. M.; Martel, P. P.; Middleton, D. G.; Miskimen, R.; Mushkarenkov, A.; Neganov, A.; Neiser, A.; Oberle, M.; Ostrick, M.; Ott, P.; Otte, P. B.; Oussena, B.; Pedroni, P.; Polonski, A.; Prakhov, S.; Ron, G.; Rostomyan, T.; Sarty, A.; Schott, D. M.; Schumann, S.; Sokhoyan, V.; Steffen, O.; Strakovsky, I. I.; Strub, Th.; Supek, I.; Thiel, M.; Thomas, A.; Unverzagt, M.; Usov, Yu. A.; Wagner, S.; Watts, D. P.; Wettig, J.; Werthm�ller, D.; Witthauer, L.; Wolfes, M.
We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball detector obtained from a study of single ?0 photoproduction on deuterium using the tagged photon beam at the Mainz Microtron. The results were obtained up to a neutron energy of 400 MeV . They are compared to previous measurements made more than 15 years ago at the pion beam at the BNL AGS.
A Bell Theorem Without Inequalities for Two Particles, Using Efficient Detectors
Daniel M. Greenberger; Michael Horne; Anton Zeilinger
We consider an entangled two-particle state that is produced from two independent down-conversion sources by the process of "entanglement-swapping", so that the particles have never met. We prove a Greenberger-Horne-Zeilinger (GHZ) type theorem, showing that the quantum mechanical perfect correlations for such a state are inconsistent with any deterministic, local, realistic theory. This theorem holds for individual events with no inequalities, for detectors of 100% efficiency.
Note: Determining the detection efficiency of excited neutral atoms by a microchannel plate detector.
Berry, Ben; Zohrabi, M; Hayes, D; Ablikim, U; Jochim, Bethany; Severt, T; Carnes, K D; Ben-Itzhak, I
We present a method for determining the detection efficiency of neutral atoms relative to keV ions. Excited D* atoms are produced by D2 fragmentation in a strong laser field. The fragments are detected by a micro-channel plate detector either directly as neutrals or as keV ions following field ionization and acceleration by a static electric field. Moreover, we propose a new mechanism by which neutrals are detected. We show that the ratio of the yield of neutrals and ions can be related to the relative detection efficiency of these species. PMID:25933901
Constriction-limited detection efficiency of superconducting nanowire single-photon detectors
NASA Astrophysics Data System (ADS)
Kerman, Andrew J.; Dauler, Eric A.; Yang, Joel K. W.; Rosfjord, Kristine M.; Anant, Vikas; Berggren, Karl K.; Gol'tsman, Gregory N.; Voronov, Boris M.
We investigate the source of the large variations in the observed detection efficiencies of superconducting nanowire single-photon detectors between many nominally identical devices. Through both electrical and optical measurements, we infer that these variations arise from "constrictions:" highly localized regions of the nanowires where the effective cross-sectional area for superconducting current is reduced. These constrictions limit the bias-current density to well below its critical value over the remainder of the wire, and thus prevent the detection efficiency from reaching the high values that occur in these devices when they are biased near the critical current density.
2010 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 49, NO. 4, AUGUST 2002 Estimate of Large CZT Detector Absolute Efficiency
He, Zhong
quality are proposed. Index Terms--CdZnTe, CZT, Monte Carlo methods, radiation detectors, simulation. I-efficiency gamma radiation detectors. In spite of the improved quality of the material and device con- struction2010 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 49, NO. 4, AUGUST 2002 Estimate of Large CZT
Analysis of the Texas A&M impact lightning detector to determine detection efficiency and site error corrections�
Leahy, Frank Byron
The Texas A&M IMProved Accuracy from Combined Technology (IMPACT) lightning detector has been analyzed for 1997 and 1998-99 to determine detection characteristics. These characteristics include stroke detection efficiency as a function of range...
High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits
Pernice, W.H.P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G.N.; Sergienko, A.V.; Tang, H.X.
Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18?ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics. PMID:23271658
A robust approach to measuring the detective quantum efficiency of radiographic detectors in a clinical setting
NASA Astrophysics Data System (ADS)
McDonald, Michael C.; Kim, H. K.; Henry, J. R.; Cunningham, I. A.
The detective quantum efficiency (DQE) is widely accepted as a primary measure of x-ray detector performance in the scientific community. A standard method for measuring the DQE, based on IEC 62220-1, requires the system to have a linear response meaning that the detector output signals are proportional to the incident x-ray exposure. However, many systems have a non-linear response due to characteristics of the detector, or post processing of the detector signals, that cannot be disabled and may involve unknown algorithms considered proprietary by the manufacturer. For these reasons, the DQE has not been considered as a practical candidate for routine quality assurance testing in a clinical setting. In this article we described a method that can be used to measure the DQE of both linear and non-linear systems that employ only linear image processing algorithms. The method was validated on a Cesium Iodide based flat panel system that simultaneously stores a raw (linear) and processed (non-linear) image for each exposure. It was found that the resulting DQE was equivalent to a conventional standards-compliant DQE with measurement precision, and the gray-scale inversion and linear edge enhancement did not affect the DQE result. While not IEC 62220-1 compliant, it may be adequate for QA programs.
Quantum efficiency of back-illuminated CCD detectors in the VUV region (30 200 nm)
NASA Astrophysics Data System (ADS)
Garnir, H. P.; Lef�bvre, P.-H.
Charge-coupled devices (CCD's) are the detectors of choice for spectroscopy of highly charged ions due to their good linearity, spatial resolution, and high quantum efficiency (QE) over a wide wavelength range going from the ?-rays to the far infrared. However, the efficiency in the UV region of back-illuminated CCDs is not well known because of the lack of commercially available calibrated light sources in that wavelength range. By using the beam-foil light source, which produces well controlled line rich spectrum all over the XUV and VUV spectra, we have been able to measure the QE of our CCD over a large wavelength range. Our results are in accordance with the data gathered from the literature and allow us to propose a "universal" curve for the QE efficiency of CCDs in the 30-200 nm region.
112-Pixel Arrays of High-Efficiency STJ X-Ray Detectors
NASA Astrophysics Data System (ADS)
Friedrich, S.; Harris, J.; Warburton, W. K.; Carpenter, M. H.; Hall, J. A.; Cantor, R.
We are developing the next generation of high-resolution high-speed X-ray detectors based on superconducting tunnel junctions (STJs). They consist of 112-pixel arrays of 208 m 208 m Ta-Al--Al-Ta tunnel junctions whose Ta absorber increases the detection efficiency compared to earlier Nb-based STJs. To read out these medium size detector arrays we have also developed a compact and scalable 32-channel preamplifier with an input voltage noise 1 nV/Hz and a dc voltage bias for stable STJ operation between Fiske mode resonances. The pixels have a uniform response across the array, an energy resolution between 7.5 and 9.5 eV FWHM at 525 eV, and can be operated at several 1,000 counts/s per pixel.
Validation of Pulse Shape Simulation for Ge detectors in the MAJORANA DEMONSTRATOR
NASA Astrophysics Data System (ADS)
Shanks, Benjamin; Majorana Collaboration
The MAJORANA DEMONSTRATOR expects to begin searching for neutrinoless double beta decay using 76 Ge-enriched detectors in 2015. The DEMONSTRATOR high purity germanium (HPGe) detectors are built in the p-type point contact (PPC) geometry. The electrode of a PPC detector is small and shallow, resulting in low intrinsic capacitance and bulk field strengths compared to the traditional coaxial HPGe configuration. These characteristics allow for discrimination of signal event candidates from background using pulse shape analysis (PSA). In order to fully understand the systematics and efficiencies of PSA cuts, the MAJORANA collaboration has developed a software package to simulate signal generation in PPC detectors. This code has been validated by comparing simulated pulses to the pulse shapes generated for given detectors using an external source. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics Program of the National Science Foundation, and the Sanford Underground Research Facility.
Effects of radiation-induced defects on the charge collection efficiency of a silicon carbide particle detector
NASA Astrophysics Data System (ADS)
Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Ohshima, Takeshi; Kojima, Kazutoshi; Nozaki, Shinji
Radiation hardness of 6H silicon carbide (SiC) p+n diode particle detectors has been studied. The charge collection efficiency (CCE) of the detectors decreases with the increased fluence of electrons with energies of 0.2 MeV and higher. Defect X2 with an activation energy of 0.5 eV was found in all detectors which showed the decreased CCE. The decreased CCE was restored to the initial value by thermal annealing of defect X2. It is concluded that defect X2 is responsible for the decreased CCE of 6H-SiC p+n diode particle detectors.
Efficiency of dislocation density reduction during heteroepitaxial growth of diamond for detector applications
NASA Astrophysics Data System (ADS)
Stehl, C.; Fischer, M.; Gsell, S.; Berdermann, E.; Rahman, M. S.; Traeger, M.; Klein, O.; Schreck, M.
The development of dislocation density and micro-strain in heteroepitaxial diamond films on iridium was measured over more than two decades of thickness up to d ? 1 mm. Simple mathematical scaling laws were derived for the decrease of dislocation density with increasing film thickness and for its correlation with micro-strain. The Raman line width as a measure of micro-strain showed a huge decrease to 1.86 cm-1, close to the value of perfect single crystals. The charge collection properties of particle detectors built from this material yield efficiencies higher than 90% in the hole-drift mode, approaching the performance of homoepitaxial films.
Constriction-limited detection efficiency of superconducting nanowire single-photon detectors
Kerman, A J; Berggren, K K; Dauler, E A; Gol'tsman, G; Rosfjord, K M; Voronov, B L; Yang, J K W; Anant, Vikas; Berggren, Karl K.; Dauler, Eric A.; Kerman, Andrew J.; Rosfjord, Kristine M.; Yang, Joel K.W.
We investigate the source of large variations in the observed detection effiiencies of superconducting nanowire single-photon detectors between many nominally identical devices. Through both electrical and optical measurements, we infer that these variations arise from "constrictions:" highly localized regions of the nanowires where the effective cross-sectional area for superconducting current is reduced. These constrictions limit the DC bias current density to well below its critical value over the remainder of the wire, and thus prevent the detection efficiency from reaching the high values that occur in these devices only when they are biased near the critical current density.
Low-filling-factor superconducting single photon detector with high system detection efficiency.
Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen
We designed, fabricated, and measured superconducting nanowire single-photon detectors (SSPDs) with low filling factor which achieve high system detection efficiency (SDE) and counting rate simultaneously. Numerical simulation reveals that high optical absorptance is possible in SSPDs even for low filing factor by tuning the device design. The SDEs of fabricated 18-50% filling factor SSPDs were measured systematically, and all SSPDs showed high SDEs of 61-80% and the lowest 18% filling factor SSPD achieved a high SDE of 69%. PMID:24216941
Numerical Simulations of Pillar Structured Solid State Thermal Neutron Detector Efficiency and Gamma Discrimination
Conway, A; Wang, T; Deo, N; Cheung, C; Nikolic, R
This work reports numerical simulations of a novel three-dimensionally integrated, {sup 10}boron ({sup 10}B) and silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and {sup 7}Li) created from the neutron - {sup 10}B reaction. In this work, the effect of both the 3-D geometry (including pillar diameter, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated to compare well with the measurement results. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible.
Using of the natural radioactive elements for determining Ge-detector efficiencies
E. G. Tertyshnik; I. E. Epifanova
A method is proposed to use of the mixture of Uran oxide and non-active matrix (e.g., NaCl) and also potassium and lanthanum for determining Ge-detector efficiencies. The preparations containing of known amouts of the U or K, or La were measured by means of the Ge-detector, which a efficiency curve has been obtained through the reference solutions of 241Am, 109Cd, 57Co, 139Ce, 137Cs, 60Co. Results the measurements were compared the activities of the preparations calculated from mass of 235U, 238U, 138La, 40K in the samples, its natural abundance, half lives and intensities of gamma lines. Discrepancy of the activities in the energy range between 163 and 1461 keV does not exeed 7 %. For correct comparison of the activities the coefficients {\\omega} were calculated, which took into consideration a varied sorption of gamma-rays in water and in mixture of the Uran oxide and matrix.
Measuring the X-ray quantum efficiency of a hybrid CMOS detector with 55Fe
NASA Astrophysics Data System (ADS)
Bongiorno, S. D.; Falcone, A. D.; Prieskorn, Z.; Griffith, C.; Burrows, D. N.
Charge coupled devices (CCDs) are currently the workhorse focal plane arrays operating aboard many orbiting astrophysics X-ray telescopes, e.g. Chandra, XMM-Newton, Swift, and Suzaku. In order to meet the count rate, power, and mission duration requirements defined by next-generation X-ray telescopes, future detectors will need to be read out faster, consume less power, and be more resistant to radiation and micrometeoroid damage than current-generation devices. The hybrid CMOS detector (HCD), a type of active pixel sensor, is currently being developed to meet these requirements. With a design architecture that involves bump bonding two semiconductor substrates together at the pixel level, these devices exhibit both the high read speed and low power consumption of CMOS readout circuitry and the high quantum efficiency (QE) of a deeply depleted silicon absorber. These devices are expected to exhibit the same excellent, high-energy quantum efficiency (QE) as deep-depletion CCDs (QE > 0.9 at 6 keV), while at the same time exhibiting superior readout flexibility, power consumption, and radiation hardness than CCDs. In this work we present a QE model for a Teledyne Imaging Sensors HyViSI HCD, which predicts QE=96% at 55Fe source energies (5.89 and 6.49 keV). We then present a QE measurement of the modeled device at the same energies, which shows QE=97�5% and is in good agreement with the model.
Quantum efficiencies of imaging detectors with alkali halide photocathodes. 1: Microchannel plates with separate and integral Csl photocathodes.
Carruthers, G R
We have measured and compared the quantum efficiencies of microchannel plate (MCP) detectors in the far- UV (below 2000-A) wavelength range using CsI photocathodes (a) deposited on the front surfaces of microchannel plates and (b) deposited on solid substrates as opaque photocathodes with the resulting photoelectrons input to microchannel plates. The efficiencies were measured in both pulse-counting and photodiode modes of operation. Typical efficiencies are ~15% at 1216 A for a CsI-coated MCP compared with 65% for an opaque CsI photocathode MCP detector. Special processing has yielded an efficiency as high as 20% for a CsI-coated MCP. This may possibly be further improved by optimization of the tilt angle of the MCP channels relative to the front face of the MCP and incident radiation. However, at present there still remains a factor of at least 3 quantum efficiency advantage in the separate opaque CsI photocathode configuration. PMID:20489984
Optimization of the Efficiency of a Neutron Detector to Measure (?, n) Reaction Cross-Section
NASA Astrophysics Data System (ADS)
Perello, Jesus; Montes, Fernando; Ahn, Tony; Meisel, Zach; Joint Institute for Nuclear Astrophysics Team
Nucleosynthesis, the origin of elements, is one of the greatest mysteries in physics. A recent particular nucleosynthesis process of interest is the charge-particle process (cpp). In the cpp, elements form by nuclear fusion reactions during supernovae. This process of nuclear fusion, (?,n), will be studied by colliding beam elements produced and accelerated at the National Superconducting Cyclotron Laboratory (NSCL) to a helium-filled cell target. The elements will fuse with ? (helium nuclei) and emit neutrons during the reaction. The neutrons will be detected for a count of fused-elements, thus providing us the probability of such reactions. The neutrons will be detected using the Neutron Emission Ratio Observer (NERO). Currently, NERO's efficiency varies for neutrons at the expected energy range (0-12 MeV). To study (?,n), NERO's efficiency must be near-constant at these energies. Monte-Carlo N-Particle Transport Code (MCNP6), a software package that simulates nuclear processes, was used to optimize NERO configuration for the experiment. MCNP6 was used to simulate neutron interaction with different NERO configurations at the expected neutron energies. By adding additional 3He detectors and polyethylene, a near-constant efficiency at these energies was obtained in the simulations. With the new NERO configuration, study of the (?,n) reactions can begin, which may explain how elements are formed in the cpp. SROP MSU, NSF, JINA, McNair Society.
Activity determination of (41)Ar using efficiency extrapolation method and 4??(PS)-4??(NaI) coincidence system.
Xie, Feng; Li, Xuesong; Dai, Yihua; Jiang, Wengang; He, Xiaobing; Yu, Gongshuo; Ni, Jianzhong
Noble gas (41)Ar was measured with a 4??-4?? coincidence system, in which gamma- and beta-rays were respectively detected with a well-type NaI(Tl) and plastic scintillator (PS) detector. The activity of (41)Ar was determined from an efficiency extrapolation method, in which the beta detector efficiency was varied by electronic discrimination using the software developed under Visual basic. In addition, high resolution gamma spectroscopy with HPGe detector was also used for activity determination of (41)Ar, and the result was satisfactory in agreement with that obtain by the efficiency extrapolation method. This work demonstrated that the activity of (41)Ar can be accurately measured by efficiency extrapolation method. PMID:25527895
A Mechanically-Cooled, Highly-Portable, HPGe-Based, Coded-Aperture Gamma-Ray Imager
Ziock, Klaus-Peter [ORNL] [ORNL; Boehnen, Chris Bensing [ORNL] [ORNL; Hayward, Jason P [ORNL] [ORNL; Raffo-Caiado, Ana Claudia [ORNL] [ORNL
Coded-aperture gamma-ray imaging is a mature technology that is capable of providing accurate and quantitative images of nuclear materials. Although it is potentially of high value to the safeguards and arms-control communities, it has yet to be fully embraced by those communities. One reason for this is the limited choice, high-cost, and low efficiency of commercial instruments; while instruments made by research organizations are frequently large and / or unsuitable for field work. In this paper we present the results of a project that mates the coded-aperture imaging approach with the latest in commercially-available, position-sensitive, High Purity Germanium (HPGe) detec-tors. The instrument replaces a laboratory prototype that, was unsuitable for other than demonstra-tions. The original instrument, and the cart on which it is mounted to provide mobility and pointing capabilities, has a footprint of ~ 2/3 m x 2 m, weighs ~ 100 Kg, and requires cryogen refills every few days. In contrast, the new instrument is tripod mounted, weighs of order 25 Kg, operates with a laptop computer, and is mechanically cooled. The instrument is being used in a program that is ex-ploring the use of combined radiation and laser scanner imaging. The former provides information on the presence, location, and type of nuclear materials while the latter provides design verification information. To align the gamma-ray images with the laser scanner data, the Ge imager is fitted and aligned to a visible-light stereo imaging unit. This unit generates a locus of 3D points that can be matched to the precise laser scanner data. With this approach, the two instruments can be used completely independently at a facility, and yet the data can be accurately overlaid based on the very structures that are being measured.
Comparison of two HPGe counting system used in activation studies for nuclear astrophysics
Sz�cs, T.; Kiss, G. G.; F�l�p, Zs. [Institute for Nuclear Research (MTA Atomki), H-4001 Debrecen, POB 51 (Hungary)
The activation method is a widely used technique to measure charged-particle induced cross sections for astrophys-ical applications. This two step technique is used for example to measure alpha-induced cross sections in ?-process related studies. The first step � in which a target is irradiated with a proton/alpha beam � is followed by the determination of the produced activity. Especially in p-process related studies in the heavier mass range, the produced radioactive nuclei decays mainly with electron-capture, resulting intense x-rays. The activity of the reaction products hence can be determine via the counting of these x-rays, and not only by counting the usually much weaker ?-rays. In this paper we compare the minimum detectable activity (MDA) of two High Purity Germanium (HPGe) detectors used for x- and ?-ray counting in activation experiments.
Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy
Rowland, Mark S. (Alamo, CA); Howard, Douglas E. (Livermore, CA); Wong, James L. (Dublin, CA); Jessup, James L. (Tracy, CA); Bianchini, Greg M. (Livermore, CA); Miller, Wayne O. (Livermore, CA)
A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.
A high efficiency, low background neutron and gamma detector for cold fusion experiments
NASA Astrophysics Data System (ADS)
Stella, B.; Celani, F.; Corradi, M.; Ferrarotto, F.; Iucci, N.; Milone, V.; Spallone, A.; Villoresi, G.
The present apparatus (named by the acrostic "FERMI" also to celebrate the 60 yr of the discovery, by Enrico Fermi and collaborators at Rome University, of the effects of moderation of neutrons) is mainly a moderated neutron detector developed for the search of cold fusion events. It is based on 7 BF 3 and 2 3He proportional counters with detection efficiency for neutrons 40%-8% in the range 1 keV-20 MeV, pulse shape acquisition and good time resolution for neutron bursts; it also allows us to perform a good reconstruction of the average original neutron energy. The neutron background measured in the Gran Sasso INFN underground laboratory is about 0.09 Hz. Gamma rays are revealed mostly by a complementary low background NaI detector with 26% solid angle coverage. The performances are controlled by a full MC simulation, experimentally tested. A high multiplicity (up to � 100) neutrons' event has been detected during background runs. The system is being upgraded by the detection and identification of charged hadrons.
A high efficiency veto to increase the sensitivity of ZEPLIN-III, a WIMP detector
Barnes, E. J. [School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3JZ (United Kingdom)
An active veto detector to complement the ZEPLIN-III two phase Xenon, direct dark matter device is described. The proposed design consists of 52 plastic scintillator segments, individually read out by high efficiency photomultipliers, coupled to a Gd loaded passive polypropylene shield. Experimental work was performed to determine the plastic scintillator characteristics which were used to inform a complete end-to-end Monte Carlo simulation of the expected performance of the new instrument, both operating alone and as an active veto detector for ZEPLIN-III. The veto device will be capable of tagging over 65% of coincident nuclear recoil events in the energy range of interest in ZEPLIN-III, and over 12% for gamma ray rejection, while contributing no significant additional background. In addition it will also provide valuable diagnostic capabilities. The inclusion of the veto to ZEPLIN-III will aid to significantly improve the sensitivity to spin independent WIMP-nucleon cross sections below 10{sup -8} pb.
Thermoacoustic tomography with detectors on an open curve: an efficient reconstruction algorithm
Kunyansky, Leonid
Practical applications of thermoacoustic tomography require numerical inversion of the spherical mean Radon transform with the centers of integration spheres occupying an open surface. Solution of this problem is needed (both in 2-D and 3-D) because frequently the region of interest cannot be completely surrounded by the detectors, as it happens, for example, in breast imaging. We present an efficient numerical algorithm for solving this problem in 2-D (similar methods are applicable in the 3-D case). Our method is based on the numerical approximation of plane waves by certain single layer potentials related to the acquisition geometry. After the densities of these potentials have been precomputed, each subsequent image reconstruction has the complexity of the regular filtration backprojection algorithm for the classical Radon transform. The peformance of the method is demonstrated in several numerical examples: one can see that the algorithm produces very accurate reconstructions if the data are accurate and...
Investigations of afterpulsing and detection efficiency recovery in superconducting nanowire single-photon detectors
Burenkov, Viacheslav; Qi, Bing; Hadfield, Robert H; Lo, Hoi-Kwong
We report on the observation of a non-uniform dark count rate in Superconducting Nanowire Single Photon Detectors (SNSPDs), specifically focusing on an afterpulsing effect present when the SNSPD is operated at a high bias current regime. The afterpulsing exists for real detection events (triggered by input photons) as well as for dark counts (no laser input). In our standard set-up, the afterpulsing is most likely to occur at around 180 ns following a detection event, for both real counts and dark counts. We characterize the afterpulsing behavior and speculate that it is not due to the SNSPD itself but rather the amplifiers used to boost the electrical output signal from the SNSPD. We show that the afterpulsing indeed disappears when we use a different amplifier with a better low frequency response. We also examine the short-lived enhancement of detection efficiency during the recovery of the SNSPD due to temporary perturbation of the bias and grounding conditions.
Investigations of afterpulsing and detection efficiency recovery in superconducting nanowire single-photon detectors
NASA Astrophysics Data System (ADS)
Burenkov, Viacheslav; Xu, He; Qi, Bing; Hadfield, Robert H.; Lo, Hoi-Kwong
We report on the observation of a non-uniform dark count rate in Superconducting Nanowire Single Photon Detectors (SNSPDs), specifically focusing on an afterpulsing effect present when the SNSPD is operated at a high bias current regime. The afterpulsing exists for real detection events (triggered by input photons) as well as for dark counts (no laser input). In our standard set-up, the afterpulsing is most likely to occur at around 180 ns following a detection event, for both real counts and dark counts. We characterize the afterpulsing behavior and speculate that it is not due to the SNSPD itself but rather the amplifiers used to boost the electrical output signal from the SNSPD. We show that the afterpulsing indeed disappears when we use a different amplifier with a better low frequency response. We also examine the short-lived enhancement of detection efficiency during the recovery of the SNSPD due to temporary perturbation of the bias and grounding conditions.
Large-sensitive-area superconducting nanowire single-photon detector at 850 nm with high detection efficiency
Li, Hao; You, Lixing; Yang, Xiaoyan; Zhang, Weijun; Liu, Xiaoyu; Chen, Sijing; Wang, Zhen; Xie, Xiaoming
Satellite-ground quantum communication requires single-photon detectors of 850-nm wavelength with both high detection efficiency and large sensitive area. We developed superconducting nanowire single-photon detectors (SNSPDs) on one-dimensional photonic crystals, which acted as optical cavities to enhance the optical absorption, with a sensitive-area diameter of 50 um. The fabricated multimode fiber coupled NbN SNSPDs exhibited a maximum system detection efficiency (DE) of up to 82% and a DE of 78% at a dark count rate of 100 Hz at 850-nm wavelength as well as a system jitter of 105 ps.
Large-sensitive-area superconducting nanowire single-photon detector at 850 nm with high detection efficiency
Hao Li; Lu Zhang; Lixing You; Xiaoyan Yang; Weijun Zhang; Xiaoyu Liu; Sijing Chen; Zhen Wang; Xiaoming Xie
Satellite-ground quantum communication requires single-photon detectors of 850-nm wavelength with both high detection efficiency and large sensitive area. We developed superconducting nanowire single-photon detectors (SNSPDs) on one-dimensional photonic crystals, which acted as optical cavities to enhance the optical absorption, with a sensitive-area diameter of 50 um. The fabricated multimode fiber coupled NbN SNSPDs exhibited a maximum system detection efficiency (DE) of up to 82% and a DE of 78% at a dark count rate of 100 Hz at 850-nm wavelength as well as a system jitter of 105 ps.
Highly efficient scheme for the implementation of optical controlled-Z gate via two-qubit polarization parity detector
NASA Astrophysics Data System (ADS)
Zhu, Meng-Zheng; Zhao, Chun-Ran; Ye, Liu
A new scheme is proposed to direct implement the optical two-qubit controlled-Z gate with the two-qubit polarization parity detector [Lin, et al., Phys. Rev. A. 80 (2009) 042311] based on weak cross-Kerr nonlinearity. The distinct advantage of the present scheme in contrast with the existing schemes is that the two-qubit polarization parity detector with classical information feed-forward allows the efficiency of our optical controlled-Z gate to be enormously enhanced due to avoiding effectively the photon bunching effects. Therefore, the present scheme is more efficient and more convenient than others in the applications of quantum communication.
Study of interstrip gap effects and efficiency for full energy detection of Double Sided Silicon Strip Detectors
NASA Astrophysics Data System (ADS)
Torresi, D.; Forneris, J.; Grassi, L.; Acosta, L.; Di Pietro, A.; Figuera, P.; Grilj, L.; Jaksi?, M.; Lattuada, M.; Mijatovi?, T.; Milin, M.; Prepolec, L.; Skukan, N.; Soi?, N.; Stanko, D.; Toki?, V.; Uroi?, M.; Zadro, M.
In this work is reported a study on the response of double sided silicon strip detectors. In order to investigate the effect of the electrode segmentation on the detector response, two experiments were performed aimed to measure the efficiency for full energy detection. Results show that the efficiency for full energy detection, that is directly related to effective width of the inter-strip region, varies with both detected ion energy and bias voltage. The experimental results are qualitatively reproduced by a simplified model based on the Shockley-Ramo-Gunn framework.
Large-sensitive-area superconducting nanowire single-photon detector at 850 nm with high detection efficiency
NASA Astrophysics Data System (ADS)
Li, Hao; Zhang, Lu; You, Lixing; Yang, Xiaoyan; Zhang, Weijun; Liu, Xiaoyu; Chen, Sijing; Wang, Zhen; Xie, Xiaoming
Satellite-ground quantum communication requires single-photon detectors of 850-nm wavelength with both high detection efficiency and large sensitive area. We developed superconducting nanowire single-photon detectors (SNSPDs) on one-dimensional photonic crystals, which acted as optical cavities to enhance the optical absorption, with a sensitive-area diameter of 50 um. The fabricated multimode fiber coupled NbN SNSPDs exhibited a maximum system detection efficiency (DE) of up to 82% and a DE of 78% at a dark count rate of 100 Hz at 850-nm wavelength as well as a system jitter of 105 ps.
An optical-beam-induced-current study of active region and charge collection efficiency of GaAs particle detectors
M. Alietti; L. Berluti; C. Canali; A. Castaldini; A. Cavallini; A. Cetronio; S. D'Auria; C. del Papa; C. Lanzieri; F. Nava; M. Proia; P. Rinaldi; A. Zichichi
In a recent paper, it was described how semi-insulating (SI) liquid encapsulated Czochralski (LEC) gallium arsenide particle detectors made by Alenia SpA have been tested and found to be understandable in terms of one function: the local charge collection efficiency. We have now measured, always within the context of the RD8 experiment, the local charge collection efficiency for these diodes
Pockels readout optical modulator: An x-ray imaging detector that maintains good efficiency over a broad energy range
Stokes, G.H.; Stupin, D.M.; Elliott, N.E.; Graser M. Jr.
We present measurements of the performance of a Pockels readout optical modulator (PROM) x-ray imaging detector using a 30-kV constant potential bremsstrahlung source. A nickel step wedge was used to measure the spatial resolution and noise of the PROM image. PROMs are unique high-efficiency x-ray detectors that image with good spatial resolution over a wide range of x-ray energy. The PROM is constructed from an optically transparent, active crystal that is sensitive to x-ray dose. This unique construction allows the use of a thick crystal to increase efficiency for x-ray detection while avoiding the spatial resolution degradation that usually accompanies thick detectors.
Substrate characterization for underwater gamma spectrometry: tank measurement results utilizing efficiencies calculated via Monte-Carlo code.
Ocone, R; Kostezh, A; Kurinenko, V; Tyshchenko, A; Derkach, G; Leone, P
In order to study the sediment contamination, underwater gamma-ray spectrometry measurements performed by the sub-marine detector Canberra HpGe with a relative efficiency of 80% were carried out in an equipped tank at the Ukrainian Hydrometeorological Institute of Kiev. Different substrates, certified sources and experiment geometrical set-up were arranged. Efficiencies were calculated by in situ object counting system (ISOCS) software. ISOCS performance tests using certified sources were carried out by comparing laboratory measurements, and measurement results for mineralogy and density performances are reported. PMID:15177333
Charge collection efficiency and space charge formation in CdTe gamma and X-ray detectors
R Matz; M Weidner
A new extended model for the charge collection efficiency in CdTe gamma and X ray detectors is presented which allows to derive from apparent experimental gamma spectra of a quasi-monochromatic source, an 241Am source in the present case, not only the ?? products of electrons and holes individually but also the sign, spatial distribution, and temporal evolution of the net
Efficient Nonlinear Detector of Binary Signals in Rayleigh Fading and Impulse Interference
Henkel, Werner
, which lead to an irreducible optimum detector. Here, our analysis is based on a two-state model show that, for jointly distributed IQ noise components, the conventional coherent detector over of an optimum detector over a fading channel with impulse noise is considered, where the noise distribution
Local State Transition of Feedback Controlled Quantum Systems with Imperfect Detector Efficiency: Part II: Accessibility Analysis for Quantum Systems
NASA Astrophysics Data System (ADS)
Sasaki, Tomotake; Hara, Shinji; Tsumura, Koji
In this paper, we analyze local state transition of controlled quantum systems under continuous quantum measurement, which is described by a matrix-valued nonlinear stochastic differential equation. To this end, we utilize the method of differential geometric analysis for systems with matrix-valued states developed in the first part of this series. The method provides us a direct and efficient way of analysis with a clear perspective. We study local state transition of the controlled quantum systems with imperfect detector efficiency which has not been studied enough in previous works. The controlled quantum system with perfect detector efficiency is also investigated as a special case. Sufficient conditions for the measurement operator and the control Hamiltonian are derived, under which the local state transition is quite limited. We also show that the conditions are satisfied in many typical situations. The results reveal fundamental nature of the controlled quantum systems under continuous quantum measurement.
Direct-reaction studies by particle-{gamma} coincidence spectroscopy using Csi-Hpge and Si-Hpge arrays
Allmond, J. M. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge TN 37831 (United States)
Particle-{gamma} and particle-{gamma}-{gamma} coincidence spectroscopy has several advantages in the study of direct reactions (particularly in inverse kinematics) since it can generally allow determination of: decay paths; high-precision level energies; multipolarities of transitions; and cross sections. Techniques for studying direct reactions by particle-{gamma} coincidence spectroscopy are presented for two cases: (1) heavy-ion reactions with CsI-HPGe, and (2) light-ion reactions with Si-HPGe. Future direct-reaction studies with radioactive ion beams (RIBs) will mostly involve low beam intensities and inverse kinematics (i.e., A{sub beam}>A{sub target}), which eliminates the traditional use of magnetic spectrometers. Particle-{gamma} coincidence spectroscopy currently provides the most viable method to study direct reactions with nuclei of any level density. In the present study, the capabilities and limitations of the technique are explored.
Direct-Reaction Studies by Particle-Gamma Coincidence Spectroscopy Using HPGe-CsI and HPGe-Si Arrays
Allmond, James M [ORNL] [ORNL
Particle- and particle- - coincidence spectroscopy has several advantages in the study of direct reactions(particularly in inverse kinematics) since it can generally allow determination of: decay paths; high-precision level energies; multipolarities of transitions; and cross sections. Techniques for studying direct reactions by particle- coincidence spectroscopy are presented for two cases: (1) heavy-ion reactions with HPGe-CsI, and (2) light-ion reactions with HPGe-Si. Future direct-reaction studies with radioactive ion beams (RIBs) will mostly involve low beam intensities and inverse kinematics (i.e., Abeam>Atarget), which eliminates the traditional use of magnetic spectrometers. Particle- coincidence spectroscopy currently provides the most viable method to study direct reactions with nuclei of any level density. In the present study, the capabilities and limitations of the technique are explored.
Charged Particle Induced Radiation damage of Germanium Detectors in Space: Two Mars Observer Gamma-Ray Detectors
NASA Technical Reports Server (NTRS)
Bruekner, J.; Koenen, M.; Evans, L. G.; Starr, R.; Bailey, S. H.; Boynton W. V.
The Mars Observer Gamma-Ray Spectrometer (MO GRS) was designed to measure gamma-rays emitted by the Martian surface. This gamma-ray emission is induced by energetic cosmic-ray particles penetrating the Martian surface and producing many secondary particles and gamma rays. The MO GRS consisted of an high-purity germanium (HPGe) detector with a passive cooler. Since radiation damage due to permanent bombardment of energetic cosmic ray particles (with energies up to several GeV) was expected for the MO GRS HPGe crystal, studies on radiation damage effects of HPGe crystals were carried on earth. One of the HPGe crystals (paradoxically called FLIGHT) was similar to the MO GRS crystal. Both detectors, MO GRS and FLIGHT, contained closed-end coaxial n-type HPGe crystals and had the same geometrical dimensions (5.6 x 5.6 cm). Many other parameters, such as HV and operation temperature, differed in space and on earth, which made it somewhat difficult to directly compare the performance of both detector systems. But among other detectors, detector FLIGHT provided many useful data to better understand radiation damage effects.
Monte Carlo simulation of the full energy peak efficiency of a WBC.
Nogueira, P; Silva, L; Teles, P; Bento, J; Vaz, P
A whole body counting system is in operation at the Nuclear and Technological Institute, in Portugal. Computational methods were used to determine the detection efficiency; a well-known source of bias in modelling the behaviour of a HPGe detector is the insufficient knowledge regarding the thickness of the lithium dead layer. In order to accurately simulate the detection system and to achieve agreement between the Monte Carlo results and the performed measurements, the value for the dead layer thickness was optimized. PMID:19819154
High quantum efficiency megavoltage imaging with thick scintillator detectors for image guided radiation therapy
NASA Astrophysics Data System (ADS)
Gopal, Arun
In image guided radiation therapy (IGRT), imaging devices serve as guidance systems to aid patient set-up and tumor volume localization. Traditionally, 2-D megavoltage x-ray imagers, referred to as electronic portal imaging devices (EPIDs), have been used for planar target localization, and have recently been extended to perform 3-D volumetric reconstruction via cone-beam computed tomography (CBCT). However, current EPIDs utilize thin and inefficient phosphor screen detectors and are subsequently limited by poor soft tissue visualization, which limits their use for CBCT. Therefore, the use of thick scintillation media as megavoltage x-ray detectors for greater x-ray sensitivity and enhanced image quality has recently been of significant interest. In this research, two candidates for thick scintillators: CsI(Tl) and terbium doped scintillation glass were investigated in separate imaging configurations. In the first configuration, a thick scintillation crystal (TSC) consisting of a thick, monolithic slab of CsI(Tl) was coupled to a mirror-lens-camera system. The second configuration is based on a fiber-optic scintillation glass array (FOSGA), wherein the scintillation glass is drawn into long fiber-optic conduits, inserted into a grid-type housing constructed out of polymer-tungsten alloy, and coupled to an array of photodiodes for digital read-out. The imaging prototypes were characterized using theoretical studies and imaging measurements to obtain fundamental metrics of imaging performance. Spatial resolution was measured based on a modulation transfer function (MTF), noise was evaluated in terms of a noise power spectrum (NPS), and overall contrast was characterized in the form of detective quantum efficiency (DQE). The imaging studies were used to optimize the TSC and FOSGA imagers and propose prototype configurations for order-of-magnitude improvements in overall image quality. In addition, a fast and simple technique was developed to measure the MTF, NPS, and DQE metrics for clinical EPID and CBCT systems based on a novel adaptation of a traditional line-pair resolution bar-pattern. This research provides two significant benefits to radiotherapy: the characterization of a new generation of thick scintillator based megavoltage x-ray imagers for CBCT based IGRT, and the novel adaptation of fundamental imaging metrics from imaging research to routine clinical performance monitoring.
Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data
NASA Astrophysics Data System (ADS)
Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Khalek, S. Abdel; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Agustoni, M.; Ahlen, S. P.; Ahmad, A.; Ahmadov, F.; Aielli, G.; �kesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Albert, J.; Albrand, S.; Verzini, M. J. Alconada; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B. M. M.; Allison, L. J.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Gonzalez, B. Alvarez; Alviggi, M. G.; Amako, K.; Coutinho, Y. Amaral; Amelung, C.; Amidei, D.; Ammosov, V. V.; Santos, S. P. Amor Dos; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angelidakis, S.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Bella, L. Aperio; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ashkenazi, A.; Ask, S.; �sman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Avolio, G.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Mayes, J. Backus; Badescu, E.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, S.; Balek, P.; Balli, F.; Banas, E.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bannoura, A. A. E.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Costa, J. Barreiro Guimar�es da; Bartoldus, R.; Barton, A. E.; Bartos, P.; Bartsch, V.; Bassalat, A.; Basye, A.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, S.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, K.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belloni, A.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Noccioli, E. Benhar; Garcia, J. A. Benitez; Benjamin, D. P.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Kuutmann, E. Bergeaas; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernard, C.; Bernat, P.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertolucci, F.; Besana, M. I.; Besjes, G. J.; Bessidskaia, O.; Besson, N.; Betancourt, C.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; De Mendizabal, J. Bilbao; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boek, T. T.; Bogaerts, J. A.; Bogdanchikov, A. G.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A. S.; Bolnet, N. M.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borri, M.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brelier, B.; Brendlinger, K.; Brennan, A. J.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T. M.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Brown, G.; Brown, J.; Renstrom, P. A. Bruckman de; Bruncko, D.
Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at TeV and corresponding to an integrated luminosity of 4.7 fb. Tag-and-probe methods using events with leptonic decays of and bosons and mesons are employed to benchmark these performance parameters. The combination of all measurements results in identification efficiencies determined with an accuracy at the few per mil level for electron transverse energy greater than 30 GeV.
Retroreflector arrays for better light collection efficiency of ?-ray imaging detectors with continuous scintillation crystals without DOI misestimation
NASA Astrophysics Data System (ADS)
Ros, A.; Lerche, Ch W.; Sebastia, A.; Sanchez, F.; Benlloch, J. M.
A method to improve light collection efficiency of ?-ray imaging detectors by using retroreflector arrays has been tested, simulations of the behaviour of the scintillation light illuminating the retroreflector surface have been made. Measurements including retroreflector arrays in the setup have also been taken. For the measurements, positron emission tomography (PET) detectors with continuous scintillation crystals have been used. Each detector module consists of a continuous LSO-scintillator of dimensions 49x49x10 mm3 and a H8500 position-sensitive photo-multiplier (PSPMT) from Hamamatsu. By using a continuous scintillation crystal, the scintillation light distribution has not been destroyed and the energy, the centroids along the x- and y-direction and the depth of interaction (DOI) can be estimated. Simulations have also been run taking into account the use of continuous scintillation crystals. Due to the geometry of the continuous scintillation crystals in comparison with pixelated crystals, a good light collection efficiency is necessary to correctly reconstruct the impact point of the ?-ray. The aim of this study is to investigate whether micro-machine retro-reflectors improve light yield without misestimation of the impact point. The results shows an improvement on the energy and centroid resolutions without worsening the depth of interaction resolution. Therefore it can be concluded that using retroreflector arrays at the entrance side of the scintillation crystal improves light collection efficiency without worsening the impact point estimation.
Quantum efficiencies of imaging detectors with alkali halide photocathodes. I - Microchannel plates with separate and integral CsI photocathodes
NASA Technical Reports Server (NTRS)
Carruthers, George R.
Measurements and comparisons have been made of the quantum efficiencies of microchannel plate (MCP) detectors in the far-UV (below 2000-A) wavelength range using CsI photocathodes (a) deposited on the front surfaces of microchannel plates and (b) deposited on solid substrates as opaque photocathodes with the resulting photoelectrons input to microchannel plates. The efficiences were measured in both pulse-counting and photodiode modes of operation. Typical efficiencies are about 15 percent at 1216 A for a CsI-coated MCP compared with 65 percent for an opaque CsI photocathode MCP detector. Special processing has yielded an efficiency as high as 20 percent for a CsI-coated MCP. This may possibly be further improved by optimization of the tilt angle of the MCP channels relative to the front face of the MCP and incident radiation. However, at present there still remains a factor of at least 3 quantum efficiency advantage in the separate opaque CsI photocathode configuration.
Quantum efficiencies of imaging detectors with alkali halide photocathodes. I - Microchannel plates with separate and integral CsI photocathodes
NASA Astrophysics Data System (ADS)
Carruthers, George R.
Measurements and comparisons have been made of the quantum efficiencies of microchannel plate (MCP) detectors in the far-UV (below 2000-A) wavelength range using CsI photocathodes (a) deposited on the front surfaces of microchannel plates and (b) deposited on solid substrates as opaque photocathodes with the resulting photoelectrons input to microchannel plates. The efficiences were measured in both pulse-counting and photodiode modes of operation. Typical efficiencies are about 15 percent at 1216 A for a CsI-coated MCP compared with 65 percent for an opaque CsI photocathode MCP detector. Special processing has yielded an efficiency as high as 20 percent for a CsI-coated MCP. This may possibly be further improved by optimization of the tilt angle of the MCP channels relative to the front face of the MCP and incident radiation. However, at present there still remains a factor of at least 3 quantum efficiency advantage in the separate opaque CsI photocathode configuration.
High-efficiency superconducting nanowire single-photon detectors fabricated from MoSi thin-films
Verma, V B; Bussi�res, F; Horansky, R D; Dyer, S D; Lita, A E; Vayshenker, I; Marsili, F; Shaw, M D; Zbinden, H; Mirin, R P; Nam, S W
We demonstrate high-efficiency superconducting nanowire single-photon detectors (SNSPDs) fabricated from MoSi thin-films. We measure a maximum system detection efficiency (SDE) of 87 +- 0.5 % at 1542 nm at a temperature of 0.7 K, with a jitter of 76 ps, maximum count rate approaching 10 MHz, and polarization dependence as low as 3.4 +- 0.7 % The SDE curves show saturation of the internal efficiency similar to WSi-based SNSPDs at temperatures as high as 2.3 K. We show that at similar cryogenic temperatures, MoSi SNSPDs achieve efficiencies comparable to WSi-based SNSPDs with nearly a factor of two reduction in jitter.
GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra
Winn, W.G.
The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.
Multiband detectors and application of nanostructured anti-reflection coatings for improved efficiency
NASA Astrophysics Data System (ADS)
Jayasinghe, J. A. Ranga Chaminda
This work describes multiband photon detection techniques based on novel semiconductor device concepts and detector designs with simultaneous detection of different wavelength radiation such as UV and IR. One aim of this investigation is to examine UV and IR detection concepts with a view to resolve some of the issues of existing IR detectors such as high dark current, non uniformity, and low operating temperature and to avoid having additional optical components such as filters in multiband detection. Structures were fabricated to demonstrate the UV and IR detection concepts and determine detector parameters: (i) UV/IR detection based on GaN/AlGaN heterostructures, (ii) Optical characterization of p-type InP thin films were carried out with the idea of developing InP based detectors, (iii) Intervalence band transitions in InGaAsP/InP heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. Device concepts, detector structures, and experimental results are discussed. In order to reduce reflection, TiO2 and SiO2 nanostructured thin film characterization and application of these as anti-reflection coatings on above mentioned detectors is also discussed.
A precise method to determine the activity of a weak neutron source using a germanium detector
Duke, M J M; Krauss, C B; Mekarski, P; Sibley, L
A standard high purity germanium detector (HPGe) was used to determine the neutron activity of a weak americium-beryllium (AmBe) neutron source. Gamma rays were created through 27Al(n,n'), 27Al(n,gamma) and 1H(n,gamma) reactions induced by the neutrons on aluminum and acrylic disks. A Monte Carlo simulation was developed to model the efficiency of the detector system. The activity of our neutron source was determined to be 305.6 +/- 4.9 n/s. The result is consistent for the different gamma rays and was verified using additional simulations and measurements of the 4483 keV gamma ray produced directly from the AmBe source.
Using surface plasmons to enhance the speed and efficiency of superconducting nanowire single-photon detectors
Hu, Xiaolong
We report our design and fabrication of superconducting nanowire single-photon detectors integrated with gold plasmonic nanostructures, which can enhance the absorption of TM-polarized light, and can enlarge the effective ...
Monte Carlo simulation of the BEGe detector response function for in vivo measurements of 241Am in the skull
NASA Astrophysics Data System (ADS)
Fant�nov�, K.; Fojt�k, P.
This paper reports on the procedure of the BEGe detector characterization for the Monte Carlo calibrations. A project is under way to improve the counting and operating capabilities of the Whole Body Counter (WBC) installed in S�RO, v.v.i. (NRPI) Prague, Czech Republic. Possible emergency monitoring should mainly benefit from the rapid, safe and flexible operation of the WBC. The system of the WBC for the detection of low energy X and gamma radiation comprises four HPGe detectors intended for the routine, emergency, and research measurements of persons internally contaminated with low-energy photon emitters, mainly actinides. Among them, 241Am is the main subject of interest. A precise detection efficiency calibration of the detector is required for the measurement of activity in individual organs and tissues. The use of physical phantoms in the calibrations is often supplemented with the application of voxel phantoms and a Monte Carlo technique that are used for the calculation of the detector response function and the full energy peak efficiency. Both experimental and computational approaches have been used for the calibration of the BEGe (Broad Energy Germanium) detector. In this paper, the process of the Monte Carlo simulation of the detector response function and the peak efficiency calculation is described. Results of the simulations are provided in the paper and discussed.
Measurements and simulations of charge collection efficiency of p +\\/n junction SiC detectors
Francesco Moscatelli; Andrea Scorzoni; Antonella Poggi; Mara Bruzzi; Stefano Lagomarsino; Stefano Mersi; Silvio Sciortino; Roberta Nipoti
Due to its excellent electrical and physical properties, silicon carbide can represent a good alternative to Si in applications like the inner tracking detectors of particle physics experiments (RD50, LHCC 2002�2003, 15 February 2002, CERN, Ginevra). In this work p+\\/n SiC diodes realised on a medium-doped (1�1015cm?3), 40?m thick epitaxial layer are exploited as detectors and measurements of their charge
GHz-gated InGaAs/InP single-photon detector with detection efficiency exceeding 55% at 1550 nm
Comandar, L. C.; Fr?hlich, B.; Dynes, J. F.; Sharpe, A. W.; Lucamarini, M.; Yuan, Z. L.; Penty, R. V.; Shields, A. J.
We report on a gated single-photon detector based on InGaAs/InP avalanche photodiodes (APDs) with a single-photon detection efficiency exceeding 55% at 1550?nm. Our detector is gated at 1?GHz and employs the self-differencing technique for gate...
Free-running InGaAs single photon detector with 1 dark count per second at 10% efficiency
NASA Astrophysics Data System (ADS)
Korzh, B.; Walenta, N.; Lunghi, T.; Gisin, N.; Zbinden, H.
We present a free-running single photon detector for telecom wavelengths based on a negative feedback avalanche photodiode (NFAD). A dark count rate as low as 1 cps was obtained at a detection efficiency of 10%, with an afterpulse probability of 2.2% for 20 ?s of deadtime. This was achieved by using an active hold-off circuit and cooling the NFAD with a free-piston stirling cooler down to temperatures of -110 �C. We integrated two detectors into a practical, 625 MHz clocked quantum key distribution system. Stable, real-time key distribution in the presence of 30 dB channel loss was possible, yielding a secret key rate of 350 bps.
Quantum efficiency of cesium iodide photocathodes in the 120-220 nm spectral range traceable to a primary detector standard
NASA Astrophysics Data System (ADS)
Rabus, H.; Kroth, U.; Richter, M.; Ulm, G.; Friese, J.; Gernh�user, R.; Kastenm�ller, A.; Maier-Komor, P.; Zeitelhack, K.
Differently prepared CsI samples have been investigated in the 120-220 nm spectral range for their quantum efficiency, spatial uniformity and the effect of radiation aging. The experiments were performed at the PTB radiometry laboratory at the Berlin synchrotron radiation facility BESSY. A calibrated GaAsP Schottky photodiode was used as transfer detector standard to establish traceability to the primary detector standard, because this type of photodiode - unlike silicon p-on-n photodiodes - proved to be of sufficiently stable response when exposed to vacuum ultraviolet radiation. The paper reviews the experimental procedures that were employed to characterize and calibrate the GaAsP photodiode and reports the results that were obtained on the investigated CsI photocathodes.
Status and Performance of an AGATA asymmetric detector
Boston, A. J.; Dimmock, M. R.; Unsworth, C.; Boston, H. C.; Cooper, R. J.; Grint, A. N.; Harkness, L. J.; Jones, M.; Nolan, P. J.; Oxley, D. C.; Slee, M. [Department of Physics, University of Liverpool, L69 7ZE (United Kingdom); Lazarus, I. H.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, WA4 4AD (United Kingdom)
High-resolution gamma-ray detectors based on high-purity germanium crystals (HPGe) are one of the key workhorses of experimental nuclear science. The technical development of such detector technology has been dramatic in recent years. Large volume, high-granularity, electrically segmented HPGe detectors have been realised and a methodology to improve position sensitivity using pulse-shape analysis coupled with the novel technique of gamma-ray tracking has been developed. Collaborations have been established in Europe (AGATA)[1] and the USA (GRETA/GRETINA)[2] to build gamma-ray tracking spectrometers. This paper discusses the performance of the first AGATA (Advanced GAmma Tracking Array) asymmetric detector that has been tested at the University of Liverpool. The use of a fully digital data acquisition system has allowed detector charge pulse shapes from a selection of well defined photon interaction positions to be analysed, yielding important information on the position sensitivity of the detector.
Security loophole in free-space quantum key distribution due to spatial-mode detector-efficiency mismatch
NASA Astrophysics Data System (ADS)
Sajeed, Shihan; Chaiwongkhot, Poompong; Bourgoin, Jean-Philippe; Jennewein, Thomas; L�tkenhaus, Norbert; Makarov, Vadim
In free-space quantum key distribution (QKD), the sensitivity of the receiver's detector channels may depend differently on the spatial mode of incoming photons. Consequently, an attacker can control the spatial mode to break security. We experimentally investigate a standard polarization QKD receiver and identify sources of efficiency mismatch in its optical scheme. We model a practical intercept-and-resend attack and show that it would break security in most situations. We show experimentally that adding an appropriately chosen spatial filter at the receiver's entrance may be an effective countermeasure.
Using An Efficient Collision Detector In The Solution Of The Find-Path Problem Of Industrial Robots
NASA Astrophysics Data System (ADS)
Sawatzky, G.; El-Zorkany, H.
In this paper an efficient approach to collision detection is proposed. Its incorporation in two approaches for the solution of the find-path problem is also presented. Collision detector is based on representing objects by a hierarchy of bounding spheres. Features of the collision detector are that computation time depends on the proximity of the objects and that the method concentrates its efforts on the parts of objects most likely to have geometric interference as determined by collision information. The use of this representation for collision detection in two approaches for the solution of the find-path problem, namely a generate and test approach and a free space representation based approach, are presented. The paper is organized as follows. First, a review of the literature is given. Second, details of the collision detector and its incorporation in a solution for the find-path problem are presented. Third, the implementation of this approach on a LISP machine and the preliminary performance tests performed using a PUMA 560 robot are discussed. Finally, conclusions and potential extensions are outlined.
Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data
ATLAS Collaboration
Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at sqrt(s) = 7 TeV and corresponding to an integrated luminosity of 4.7/fb. Tag-and-probe methods using events with leptonic decays of W and Z bosons and J/psi mesons are employed to benchmark these performance parameters. The combination of all measurements results in identification efficiencies determined with an accuracy at the few per mil level for electron transverse energy greater than 30 GeV.
Enhanced quantum efficiency of high-purity silicon imaging detectors by ultralow temperature surface modification using Sb doping
NASA Technical Reports Server (NTRS)
Blacksberg, Jordana; Hoenk, Michael E.; Elliott, S. Tom; Holland, Stephen E.; Nikzad, Shouleh
A low temperature process for Sb doping of silicon has been developed as a backsurface treatment for high-purity n-type imaging detectors. Molecular beam epitaxy (MBE) is used to achieve very high dopant incorporation in a thin, surface-confined layer. The growth temperature is kept below 450 (deg)C for compatibility with Al-metallized devices. Imaging with MBE-modified 1kx1k charge coupled devices (CCDs) operated in full depletion has been demonstrated. Dark current is comparable to the state-of-the-art process, which requires a high temperature step. Quantum efficiency is improved, especially in the UV, for thin doped layers placed closer to the backsurface. Near 100% internal quantum efficiency has been demonstrated in the ultraviolet for a CCD with a 1.5 nm silicon cap layer.
Measurements of the modulation transfer function, normalized noise power spectrum and detective quantum efficiency for two flat panel detectors: a fluoroscopic and a cone beam computer tomography flat panel detectors.
Ben�tez, Ricardo Betancourt; Ning, Ruola; Conover, David; Liu, Shaohua
The physical performance of two Flat Panel Detectors has been evaluated. The first Flat Panel Detector is for Fluoroscopic applications, Varian PaxScan 2520, and the second is for Cone Beam Computer Tomography applications, Varian PaxScan 4030CB. First, the spectrum of the X-ray source was measured. Second, the linearity of the detectors was investigated by using an ionization chamber and the average ADU values of the detectors. Third, the temporal resolution was characterized by evaluating their image lag. Fourth, their spatial resolution was characterized by the pre-sampling Modulation Transfer Function. Fifth, the Normalized Noise Power Spectrum was calculated for various exposures levels. Finally, the Detective Quantum Efficiency was obtained as a function of spatial frequency and entrance exposure. The results illustrate that the physical performance in Detective Quantum Efficiency and Normalized Noise Power Spectrum of the Cone Beam Computer Tomography detector is superior to that of the fluoroscopic detector whereas the latter detector has a higher spatial resolution as demonstrated by larger values of its Modulation Transfer Function at large spatial frequencies. PMID:19923685
Analytical modeling of relative luminescence efficiency of Al2O3:C optically stimulated luminescence detectors exposed to high-energy heavy charged particles
Gabriel O Sawakuchi; Eduardo G Yukihara
The objective of this work is to test analytical models to calculate the luminescence efficiency of Al2O3:C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytical expression for the relative luminescence efficiency based on the average radial dose distribution produced
High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation
Chiles, Marion M. (Knoxville, TN); Mihalczo, John T. (Oak Ridge, TN); Blakeman, Edward D. (Oak Ridge, TN)
A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.
High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation
Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.
A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.
Calibration Analyses and Efficiency Studies for the Anti Coincidence Detector on the Fermi Gamma Ray Space Telescope
Kachulis, Chris; /Yale U. /SLAC
The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope provides charged particle rejection for the Large Area Telescope (LAT). We use two calibrations used by the ACD to conduct three studies on the performance of the ACD. We examine the trending of the calibrations to search for damage and find a timescale over which the calibrations can be considered reliable. We also calculated the number of photoelectrons counted by a PMT on the ACD from a normal proton. Third, we calculated the veto efficiencies of the ACD for two different veto settings. The trends of the calibrations exhibited no signs of damage, and indicated timescales of reliability for the calibrations of one to two years. The number of photoelectrons calculated ranged from 5 to 25. Large errors in the effect of the energy spectrum of the charged particles caused these values to have very large errors of around 60 percent. Finally, the veto efficiencies were found to be very high at both veto values, both for charged particles and for the lower energy backsplash spectrum. The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope is a detector system built around the silicon strip tracker on the Large Area Telescope (LAT). The purpose of the ACD is to provide charged particle rejection for the LAT. To do this, the ACD must be calibrated correctly in flight, and must be able to efficiently veto charged particle events while minimizing false vetoes due to 'backsplash' from photons in the calorimeter. There are eleven calibrations used by the ACD. In this paper, we discuss the use of two of these calibrations to preform three studies on the performance of the ACD. The first study examines trending of the calibrations to check for possible hardware degradation. The second study uses the calibrations to explore the efficiency of an on-board hardware veto. The third study uses the calibrations to calculate the number of photoelectrons seen by each PMT when a minimum ionizing particle is detected, which is a useful value for performing simulations.
Spatial resolution and efficiency of microchannel plate detectors with neutron converter films
NASA Astrophysics Data System (ADS)
Cazalas, Edward; Trivelpiece, Cory; Jovanovic, Igor
An investigation into the potential neutron detection efficiency gains that could be made to microchannel plates (MCPs) has been conducted by a GEANT4 simulation. Thin-film neutron converters are coupled to the upstream-side of the MCP. MCPs with and without pre-existing neutron sensitivity were examined. A study into potential film materials favors a Gd2O3 converter film utilized in thin-film and pillar geometries for straight-channel MCPs. The objective was to increase thermal neutron detection efficiency without sacrificing the spatial resolution of the system by studying (1) the balance between capture efficiency and charged particle product production and range to optimize detection efficiency, and (2) the extent of radial straggling that the reaction products undergo as they are transmitted through the neutron converter and MCP, which affects spatial resolution. Our investigation reveals that an increase in efficiency of 9.9% can be achieved for an MCP without preexisting neutron sensitivity using a film geometry neutron converter of 4-?m thickness. An increase in efficiency of 4.3% can be achieved for a neutron-sensitive MCP using a pillar-type converter of 4-?m thickness. Degradation of spatial resolution is not significant for either film or pillar geometries with thicknesses in the range 0.5-10 ?m.
Analysis of factors affecting the estimation of detective quantum efficiency of digital X-ray detectors within high and low spatial frequency ranges
M. I. Zelikman; S. P. Kabanov; S. A. Kruchinin; D. P. Lobov
After harmonizing the corresponding international standard and introduction of GOST R IEC 62220?1?06, there is an opportunity to estimate the general character? istic of image quality in digital Xray detectors�detective quantum efficiency (DQE). DQE is a function of spatial frequency in the radiation dose detector plane. The func? tion should be measured using standard monitoring sys? tems and methods (2).
Proton-induced radiation damage in germanium detectors
NASA Technical Reports Server (NTRS)
Brueckner, J.; Koerfer, M.; Waenke, H.; Schroeder, A. N. F.; Filges, D.; Dragovitsch, P.; Englert, P. A. J.; Starr, R.; Trombka, J. I.
High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10 to the 8th protons/sq cm (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation, all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage, the detectors were stepwise-annealed at temperatures below 110 C, while kept in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged-particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.
GEANT4 calibration of gamma spectrometry efficiency for measurements of airborne radioactivity on filter paper.
Alrefae, Tareq
A simple method of efficiency calibration for gamma spectrometry was performed. This method, which focused on measuring airborne radioactivity collected on filter paper, was based on Monte Carlo simulations using the toolkit GEANT4. Experimentally, the efficiency values of an HPGe detector were calculated for a multi-gamma disk source. These efficiency values were compared to their counterparts produced by a computer code that simulated experimental conditions. Such comparison revealed biases of 24, 10, 1, 3, 7, and 3% for the radionuclides (photon energies in keV) of Ce (166), Sn (392), Cs (662), Co (1,173), Co (1,333), and Y (1,836), respectively. The output of the simulation code was in acceptable agreement with the experimental findings, thus validating the proposed method. PMID:25271933
Stability and quantum efficiency performance of silicon photodiode detectors in the far ultraviolet.
Canfield, L R; Kerner, J; Korde, R
Recent improvements in silicon photodiode fabrication technology have resulted in the production of photodiodes which are stable after prolonged exposure to short wavelength radiation and which have efficiencies in the far ultraviolet close to those predicted using a value of 3.63 eV for electron-hole pair production in Si. Quantum efficiency and stability data are presented in the 6-124-eV region for several variations on the basic successful design and on devices with extremely thin silicon dioxide antireflecting/passivating layers. The results indicate that the oxide is dominant in determining many of the performance parameters and that a stable efficient far ultraviolet diode can be fabricated by careful control of the Si-SiO(2) interface quality. PMID:20555802
Stability and quantum efficiency performance of silicon photodiode detectors in the far ultraviolet
NASA Astrophysics Data System (ADS)
Canfield, L. R.; Kerner, Jonathan; Korde, Raj
Recent improvements in silicon photodiode fabrication technology have resulted in the production of photodiodes which are stable after prolonged exposure to short wavelength radiation and which have efficiencies in the far ultraviolet close to those predicted using a value of 3.63 eV for electron-hole pair production in Si. Quantum efficiency and stability data are presented in the 6-124-eV region for several variations on the basic successful design and on devices with extremely thin silicon dioxide antireflecting/passivating layers. The results indicate that the oxide is dominant in determining many of the performance parameters and that a stable efficient far ultraviolet diode can be fabricated by careful control of the Si-SiO2 interface quality.
Towards THGEM UV-photon detectors for RICH: on single-photon detection efficiency in Ne/CH4 and Ne/CF4
NASA Astrophysics Data System (ADS)
Azevedo, C. D. R.; Cortesi, M.; Lyashenko, A. V.; Breskin, A.; Chechik, R.; Miyamoto, J.; Peskov, V.; Escada, J.; Veloso, J. F. C. A.; dos Santos, J. M. F.
The article deals with the detection efficiency of UV-photon detectors consisting of Thick Gas Electron Multipliers (THGEM) coated with CsI photocathode, operated in atmospheric Ne/CH4 and Ne/CF4 mixtures. We report on the photoelectron extraction efficiency from the photocathode into these gas mixtures, and on the photoelectron collection efficiency into the THGEM holes. Full collection efficiency was reached in all gases investigated, in some cases at relatively low multiplication. High total detector gains for UV photons, in excess of 105, were reached at relatively low operation voltages with a single THGEM element. We discuss the photon detection efficiency in the context of possible application to RICH.
Towards THGEM UV-photon detectors for RICH: on single-photon detection efficiency in Ne/CH$_{4} and Ne/CF$_4$
Azevedo, C D R; Lyashenko, A V; Breskin, A; Chechik, R; Miyamoto, J; Peskov, V; Escada, J; Veloso, J F C A; dos Santos, J M F; 10.1088/1748-0221/5/01/P01002
The article deals with the detection efficiency of UV-photon detectors consisting of Thick Gas Electron Multipliers (THGEM) coated with CsI photocathode, operated in atmospheric Ne/CH4 and Ne/CF4 mixtures. We report on the photoelectron extraction efficiency from the photocathode into these gas mixtures, and on the photoelectron collection efficiency into the THGEM holes. Full collection efficiency was reached in all gases investigated, in some cases at relatively low multiplication. High total detector gains for UV photons, in excess of 10^5, were reached at relatively low operation voltages with a single THGEM element. We discuss the photon detection efficiency in the context of possible application to RICH.
High quantum efficiency and low dark count rate in multi-layer superconducting nanowire single-photon detectors
Jafari Salim, A., E-mail: firstname.lastname@example.com; Eftekharian, A. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Hamed Majedi, A., E-mail: email@example.com [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Harvard University, Cambridge, Massachusetts 02138 (United States); Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada)
In this paper, we theoretically show that a multi-layer superconducting nanowire single-photon detector (SNSPD) is capable of approaching characteristics of an ideal SNSPD in terms of the quantum efficiency, dark count, and band-width. A multi-layer structure improves the performance in two ways. First, the potential barrier for thermally activated vortex crossing, which is the major source of dark counts and the reduction of the critical current in SNSPDs is elevated. In a multi-layer SNSPD, a vortex is made of 2D-pancake vortices that form a stack. It will be shown that the stack of pancake vortices effectively experiences a larger potential barrier compared to a vortex in a single-layer SNSPD. This leads to an increase in the experimental critical current as well as significant decrease in the dark count rate. In consequence, an increase in the quantum efficiency for photons of the same energy or an increase in the sensitivity to photons of lower energy is achieved. Second, a multi-layer structure improves the efficiency of single-photon absorption by increasing the effective optical thickness without compromising the single-photon sensitivity.
Patient-dependent count-rate adaptive normalization for PET detector efficiency with delayed-window coincidence events
NASA Astrophysics Data System (ADS)
Niu, Xiaofeng; Ye, Hongwei; Xia, Ting; Asma, Evren; Winkler, Mark; Gagnon, Daniel; Wang, Wenli
Quantitative PET imaging is widely used in clinical diagnosis in oncology and neuroimaging. Accurate normalization correction for the efficiency of each line-of- response is essential for accurate quantitative PET image reconstruction. In this paper, we propose a normalization calibration method by using the delayed-window coincidence events from the scanning phantom or patient. The proposed method could dramatically reduce the �ring� artifacts caused by mismatched system count-rates between the calibration and phantom/patient datasets. Moreover, a modified algorithm for mean detector efficiency estimation is proposed, which could generate crystal efficiency maps with more uniform variance. Both phantom and real patient datasets are used for evaluation. The results show that the proposed method could lead to better uniformity in reconstructed images by removing ring artifacts, and more uniform axial variance profiles, especially around the axial edge slices of the scanner. The proposed method also has the potential benefit to simplify the normalization calibration procedure, since the calibration can be performed using the on-the-fly acquired delayed-window dataset.
Patient-dependent count-rate adaptive normalization for PET detector efficiency with delayed-window coincidence events.
Niu, Xiaofeng; Ye, Hongwei; Xia, Ting; Asma, Evren; Winkler, Mark; Gagnon, Daniel; Wang, Wenli
Quantitative PET imaging is widely used in clinical diagnosis in oncology and neuroimaging. Accurate normalization correction for the efficiency of each line-of- response is essential for accurate quantitative PET image reconstruction. In this paper, we propose a normalization calibration method by using the delayed-window coincidence events from the scanning phantom or patient. The proposed method could dramatically reduce the 'ring' artifacts caused by mismatched system count-rates between the calibration and phantom/patient datasets. Moreover, a modified algorithm for mean detector efficiency estimation is proposed, which could generate crystal efficiency maps with more uniform variance. Both phantom and real patient datasets are used for evaluation. The results show that the proposed method could lead to better uniformity in reconstructed images by removing ring artifacts, and more uniform axial variance profiles, especially around the axial edge slices of the scanner. The proposed method also has the potential benefit to simplify the normalization calibration procedure, since the calibration can be performed using the on-the-fly acquired delayed-window dataset. PMID:26086713
The detective quantum efficiency of photon-counting x-ray detectors using cascaded-systems analyses
Tanguay, Jesse [Robarts Research Institute and Department of Medical Biophysics, Western University, London, Ontario N6A 5C1 (Canada); Yun, Seungman [Biomedical Engineering Program, Western University, London, Ontario N6A 5C1 (Canada); School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Cunningham, Ian A. [Robarts Research Institute, Department of Medical Biophysics, and Biomedical Engineering Program, Western University, London, Ontario N6A 5C1 (Canada)
Purpose: Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. The purpose of this study is to extend cascaded-systems analyses (CSA) to the description of image quality and the detective quantum efficiency (DQE) of SPC systems. Methods: Point-process theory is used to develop a method of propagating the mean signal and Wiener noise-power spectrum through a thresholding stage (required to identify x-ray interaction events). The new transfer relationships are used to describe the zero-frequency DQE of a hypothetical SPC detector including the effects of stochastic conversion of incident photons to secondary quanta, secondary quantum sinks, additive noise, and threshold level. Theoretical results are compared with Monte Carlo calculations assuming the same detector model. Results: Under certain conditions, the CSA approach can be applied to SPC systems with the additional requirement of propagating the probability density function describing the total number of image-forming quanta through each stage of a cascaded model. Theoretical results including DQE show excellent agreement with Monte Carlo calculations under all conditions considered. Conclusions: Application of the CSA method shows that false counts due to additive electronic noise results in both a nonlinear image signal and increased image noise. There is a window of allowable threshold values to achieve a high DQE that depends on conversion gain, secondary quantum sinks, and additive noise.
An efficient Novelty Detector for online fault diagnosis based on Least Squares Support Vector Machines
Taimoor S. Khawaja; George Georgoulas; George Vachtsevanos
A paradigm shift in the standard operating procedures (SOP) is underway in the reliability and health management industry. As the community transitions from traditional preventive maintenance procedures to modern predictive or health-based management systems, areas such as efficient online monitoring and diagnosis schemes based on real-time observations have emerged as key research subjects for engineers. Most diagnostic systems require data
New measurement of the Fano factor of mercuric iodide. [astronomical x-ray detector charge collection efficiency
NASA Technical Reports Server (NTRS)
Ricker, G. R.; Vallerga, J. V.; Dabrowski, A. J.; Iwanczyk, J. S.; Entine, G.
It is pointed out that mercuric iodide (HgI2) shows great promise as a high-resolution X-ray detector for use in X-ray astronomy. Development of mercuric iodide for astronomical work has required investigation of the temperature dependence of the HgI2 crystal parameters such as leakage current, resolution, and mobility of the charge carriers. The first studies in connection with these investigations have led to a new value of the Fano factor of 0.19 + or - 0.03. The best value previously reported was 0.27 measured at room temperature. The new upper limit of 0.19 for the HgI2 Fano factor was determined by cooling the HgI2 crystal and preamp to -20 C. It is concluded that room-temperature energy resolution of HgI2 is not limited by charge generation statistics but rather by collection efficiency.
Cosmic Microwave Background Polarization Detector with High Efficiency, Broad Bandwidth, and Highly Symmetric Coupling to Transition Edge Sensor Bolometers
NASA Technical Reports Server (NTRS)
Wollack, E.; Cao, N.; Chuss, D.; Denis, K.; Hsieh, W.-T.; Moseley, S. Harvey; Schneider, G.; Stevenson, T.; Travers, D.; U-yen, K.
Four probe antennas transfer signals from waveguide to microstrip lines. The probes not only provide broadband impedance matching, but also thermally isolate waveguide and detector. In addition, we developed a new photonic waveguide choke joint design, with four-fold symmetry, to suppress power leakage at the interface. We have developed facilities to test superconducting circuit elements using a cryogenic microwave probe station, and more complete systems in waveguide. We used the ring resonator shown below to measure a dielectric loss tangent < 7x10(exp -4) over 10 - 45 GHz. We have combined component simulations to predict the overall coupling from waveguide modes to bolometers. The result below shows the planar circuit and waveguide interface can utilize the high beam symmetry of HE11 circular feedhorns with > 99% coupling efficiency over 30% fractional bandwidth.
The effect of the displacement damage on the Charge Collection Efficiency in Silicon Drift Detectors for the LOFT satellite
Del Monte, E; Bozzo, E; Cadoux, F; Rachevski, A; Zampa, G; Zampa, N; Feroci, M; Pohl, M; Vacchi, A
The technology of Silicon Drift Detectors (SDDs) has been selected for the two instruments aboard the Large Observatory For X-ray Timing (LOFT) space mission. LOFT underwent a three year long assessment phase as candidate for the M3 launch opportunity within the "Cosmic Vision 2015 -- 2025" long-term science plan of the European Space Agency. During the LOFT assessment phase, we studied the displacement damage produced in the SDDs by the protons trapped in the Earth's magnetosphere. In a previous paper we discussed the effects of the Non Ionising Energy Losses from protons on the SDD leakage current. In this paper we report the measurement of the variation of Charge Collection Efficiency produced by displacement damage caused by protons and the comparison with the expected damage in orbit.
PSD Methods Comparison and Discrimination Efficiency Study for LaBr3:Ce Detector
Cang, Jirong; Zeng, Zhi; Cheng, Jianping; Liu, Yinong; Li, Junli
LaBr3:Ce scintillator has been widely studied for nuclear spectroscopy because of its optimal energy resolution (radiation background of LaBr3:Ce is a critical issue, and the Pulse Shape Discrimination (PSD) is proved to be efficient and a potential method to suppress the alpha background from the 227Ac. In this paper, a detailed comparison of 3 digital PSD algorithms, the Charge Comparison Method, the Mean Time Method and the Gamma-Alpha Model Analysis Method, for alpha and gamma discrimination in LaBr3:Ce was done. The algorithm parameters and discrimination efficiency were analyzed and optimized for each method. Moreover, for the CCM, the correlation between the CCM feature value distribution and the total charge (energy) was quantitatively analyzed, and a fitting equation of the correlation is inferred and verified with experiment. With the equation, an energy-dependent threshold was chosen to optimize the discrim...
Influence of radionuclide adsorption on detection efficiency and energy resolution for flow-cell radiation detectors
T. A. DeVol; M. E. Keillor; L. W. Burggraf
Flow-cell and batch test experiments were performed to determine the uranyl ion adsorption onto and\\/or complexation with CaF2:Eu scintillator as a function of pH. The flow-cell experiments were modeled with an energy dispersive Monte Carlo algorithm. At pH 2, the flow-cell and batch tests gave consistent results, detection efficiency ~60% and distribution coefficient (Kd ) ~0.3-0.7 mL\\/g, with the model.
Charge collection efficiency mapping of interdigitated 4H�SiC detectors
E. Vittone; N. Skukan; �. Pastuovi?; P. Olivero; M. Jaksic
The Ion Beam Induced Charge (IBIC) technique was used to map the charge collection efficiency (CCE) of a 4H�SiC photodetector with coplanar interdigitated Schottky barrier electrodes and a common ohmic contact on the back side.IBIC maps were obtained using focused proton beams with energies of 0.9 and 1.5MeV, at different bias voltages and different sensitive electrode configurations (charge collection at
PSD Methods Comparison and Discrimination Efficiency Study for LaBr3:Ce Detector
Jirong Cang; Ming Zeng; Zhi Zeng; Jianping Cheng; Yinong Liu; Junli Li
LaBr3:Ce scintillator has been widely studied for nuclear spectroscopy because of its optimal energy resolution (radiation background of LaBr3:Ce is a critical issue, and the Pulse Shape Discrimination (PSD) is proved to be efficient and a potential method to suppress the alpha background from the 227Ac. In this paper, a detailed comparison of 3 digital PSD algorithms, the Charge Comparison Method, the Mean Time Method and the Gamma-Alpha Model Analysis Method, for alpha and gamma discrimination in LaBr3:Ce was done. The algorithm parameters and discrimination efficiency were analyzed and optimized for each method. Moreover, for the CCM, the correlation between the CCM feature value distribution and the total charge (energy) was quantitatively analyzed, and a fitting equation of the correlation is inferred and verified with experiment. With the equation, an energy-dependent threshold was chosen to optimize the discrimination efficiency. Therefore, it can be expected that a correction of the alpha and gamma PSD spectrum would also be done with the equation, to achieve more accurate result.
An efficient procedure for tomotherapy treatment plan verification using the on-board detector
NASA Astrophysics Data System (ADS)
Pisaturo, O.; Mi�ville, F.; Tercier, P.-A.; Allal, A. S.
In this work, a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD) has been developed. This procedure allows verification of plans with static and dynamic jaws (TomoEDGE). A convolution-based calculation model has been derived in order to link the leaf control sinogram from the treatment planning system to the data acquired by the OBD during a static couch procedure. The convolution kernel has been optimized using simple plans calculated in the Tomotherapy Cheese phantom. The optimal kernel has been found to be a lorentzian function, whose parameter ? is 0.186 for the 1 cm jaw opening, 0.232 for the 2.5 cm jaw opening and 0.373 for the 5 cm jaw opening. The evaluation has been performed with a ?-index analysis. The dose criterion was 3% of the 95th percentile of the dose distribution and the distance-to-agreement criterion is 2 mm. In order to validate the procedure, it has been applied to around 50 clinical treatment plans, which had already been validated by the Delta4 phantom (Scandidos, Sweden). 96% of the tested plans have passed the criteria. Concerning the other 4%, significant discrepancies between the leaf pattern in the leaf control sinogram and the OBD data have been shown, which might be due to differences in the leaf open time. This corresponds also to a higher sensitivity of this method over the Delta4, adding the possibility of better monitoring the treatment delivery.
Study on the novel neutron-to-proton convertor for improving the detection efficiency of a triple GEM based fast neutron detector
NASA Astrophysics Data System (ADS)
Wang, Xiao-Dong; Yang, He-Run; Ren, Zhong-Guo; Zhang, Jun-We; Yang, Lei; Zhang, Chun-Hui; Ha, Ri-Ba-La; An, L�-Xing; Hu, Bi-Tao
A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier (GEM) detector, which, coupled with a novel multi-layered high-density polyethylene (HDPE) as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with 55Fe X-ray source to ensure that it has a good performance. The effective gain and obtained energy resolution is 5.0�104 and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38. Supported by National Natural Science Foundation of China (11135002, 11305232, 11175076)
Theoretical analysis of the effect of charge-sharing on the Detective Quantum Efficiency of single-photon counting segmented silicon detectors
NASA Astrophysics Data System (ADS)
Marchal, J.
A detector cascaded model is proposed to describe charge-sharing effect in single-photon counting segmented silicon detectors. Linear system theory is applied to this cascaded model in order to derive detector performance parameters such as large-area gain, presampling Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) as a function of energy detection threshold. This theory is used to model one-dimensional detectors (i.e. strip detectors) where X-ray-generated charge can be shared between two sampling elements, but the concepts developed in this article can be generalized to two-dimensional arrays of detecting elements (i.e. pixels detectors). The zero-frequency DQE derived from this model is consistent with expressions reported in the literature using a different method. The ability of this model to simulate the effect of charge sharing on image quality in the spatial frequency domain is demonstrated by applying it to a hypothetical one-dimensional single-photon counting detector illuminated with a typical mammography spectrum.
Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems
E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen
Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object�s composition. Field-portable systems, such as Idaho National Laboratory�s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec�s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.
Application of the Monte Carlo method for the efficiency calibration of CsI and NaI detectors for gamma-ray measurements from terrestrial samples.
Baccouche, S; Al-Azmi, D; Karunakara, N; Trabelsi, A
Gamma-ray measurements in terrestrial/environmental samples require the use of high efficient detectors because of the low level of the radionuclide activity concentrations in the samples; thus scintillators are suitable for this purpose. Two scintillation detectors were studied in this work; CsI(Tl) and NaI(Tl) with identical size for measurement of terrestrial samples for performance study. This work describes a Monte Carlo method for making the full-energy efficiency calibration curves for both detectors using gamma-ray energies associated with the decay of naturally occurring radionuclides (137)Cs (661keV), (40)K (1460keV), (238)U ((214)Bi, 1764keV) and (232)Th ((208)Tl, 2614keV), which are found in terrestrial samples. The magnitude of the coincidence summing effect occurring for the 2614keV emission of (208)Tl is assessed by simulation. The method provides an efficient tool to make the full-energy efficiency calibration curve for scintillation detectors for any samples geometry and volume in order to determine accurate activity concentrations in terrestrial samples. PMID:21852143
Exploiting Ballistic Electrons in a Uni-Traveling Carrier Traveling Wave PhotoDetector for Efficient Generation of Sub-MM Waves
Asher Madjar; Peter R. Herczfeld; Arye Rosen; Paul Yu
The Generation of microwave signals by heterodyning two optical signals has been demonstrated in the past. However, so far this approach is limited in bandwidth, power and efficiency. In this paper we present an analysis of optical heterodyning in the uni-traveling carrier traveling wave photo detector taking into account the effect of ballistic electrons. The analysis is validated by comparison
Development of a CZT drift ring detector for X and ? ray spectroscopy
NASA Astrophysics Data System (ADS)
Alruhaili, A.; Sellin, P. J.; Lohstroh, A.; Boothman, V.; Veeramani, P.; Veale, M. C.; Sawhney, K. J. S.; Kachkanov, V.
CdTe and CZT detectors are considered better choices for high energy ? and X-ray spectroscopy in comparison to Si and HPGe detectors due to their good quantum efficiency and room temperature operation. The performance limitations in CdTe and CZT detectors are mainly associated with poor hole transport and trapping phenomena. Among many techniques that can be used to eliminate the effect of the poor charge transport properties of holes in CdTe and CZT material, the drift ring technique shows promising results. In this work, the performance of a 2.3 mm thick CZT drift ring detector is investigated. Spatially resolved measurements were carried out with an X-ray microbeam (25 and 75 keV) at the Diamond Light Source synchrotron to study the response uniformity and extent of the active area. Higher energy photon irradiation was also carried out at up to 662 keV using different radioisotopes to complement the microbeam data. Different biasing schemes were investigated in terms of biasing the cathode rear electrode (bulk field) and the ring electrodes (lateral fields). The results show that increasing the bulk field with fixed-ratio ring biases and lateral fields with fixed bulk fields increase the active area of the device significantly, which contrasts with previous studies in CdTe, where only an increasing lateral field resulted in an improvement of device performance. This difference is attributed to the larger thickness of the CZT device reported here.
High-sensitivity Compton imaging with position-sensitive Si and Ge detectors
NASA Astrophysics Data System (ADS)
Vetter, K.; Burks, M.; Cork, C.; Cunningham, M.; Chivers, D.; Hull, E.; Krings, T.; Manini, H.; Mihailescu, L.; Nelson, K.; Protic, D.; Valentine, J.; Wright, D.
We report on the development of high-sensitivity and compact Compton imaging systems built of large and position-sensitive Si(Li) and HPGe detectors. The primary goal of this effort is to provide improved capabilities in the passive detection of nuclear materials for homeland security. Our detectors are implemented in double-sided strip configuration, which�along with digital signal processing�provides energies and three-dimensional position information of individual ?-ray interactions. ?-Ray tracking algorithms then determine the scattering sequence of the ?-ray, which in turn allows us�employing the Compton scattering formula�to reconstruct a cone of possible incident angles and ultimately an image. This Compton imaging concept enables large-field-of-view ?-ray imaging without the use of a heavy collimator or aperture. The intrinsically high-energy resolution of the detectors used, the excellent position resolution we have demonstrated, both combined with the high efficiency of large-volume detectors is the basis for high Compton imaging sensitivity. These capabilities are being developed to identify and localize potential threat sources and to potentially increase the sensitivity in detecting weak sources out of the midst of natural, medical, or commercial sources. ?-ray imaging provides a new degree of freedom to distinguish between spatial and temporal background fluctuations and compact threat sources.
GHz-gated InGaAs/InP single-photon detector with detection efficiency exceeding 55% at 1550 nm
Lucian C. Comandar; Bernd Fr�hlich; James F. Dynes; Andrew W. Sharpe; Marco Lucamarini; Zhiliang Yuan; Richard V. Penty; Andrew J. Shields
We report on a gated single-photon detector based on InGaAs/InP avalanche photodiodes (APDs) with a single-photon detection efficiency exceeding 55% at 1550 nm. Our detector is gated at 1 GHz and employs the self-differencing technique for gate transient suppression. It can operate nearly dead time free, except for the one clock cycle dead time intrinsic to self-differencing, and we demonstrate a count rate of 500 Mcps. We present a careful analysis of the optimal driving conditions of the APD measured with a dead time free detector characterization setup. It is found that a shortened gate width of 360 ps together with an increased driving signal amplitude and operation at higher temperatures leads to improved performance of the detector. We achieve an afterpulse probability of 7% at 50% detection efficiency with dead time free measurement and a record efficiency for InGaAs/InP APDs of 55% at an afterpulse probability of only 10.2% with a moderate dead time of 10 ns.
Quantum efficiency and noise equivalent power of nanostructured, NbN, single-photon detectors in the wavelength range from visible to infrared
A. Korneev; V. Matvienko; O. Minaeva; I. Milostnaya; I. Rubtsova; G. Chulkova; K. Smirnov; V. Voronov; G. Gol'tsman; W. Slysz; A. Pearlman; A. Verevkin; R. Sobolewski
We present our studies on the quantum efficiency (QE) and the noise equivalent power (NEP) of the latest-generation, nanostructured, superconducting, single-photon detectors (SSPDs) in the wavelength range from 0.5 to 5.6 ?m, operated at temperatures in the 2.0- to 4.2-K range. Our detectors are designed as 4-nm-thick and 100-nm-wide NbN meander-shaped stripes, patterned by electron-beam lithography and cover a 10�10-?m2
Dewberry, R.; Young, J.
In reference 1 the authors described {gamma}-ray holdup assay of a Mossbauer spectroscopy instrument where they utilized two axial symmetric cylindrical shell acquisitions and two disk source acquisitions to determine Am-241 and Np-237 contamination. The measured contents of the two species were determined using a general detector efficiency calibration taken from a 12-inch point source.2 The authors corrected the raw spectra for container absorption as well as for geometry corrections to transform the calibration curve to the applicable axial symmetric cylindrical source - and disk source - of contamination. The authors derived the geometry corrections with exact calculus that are shown in equations (1) and (2) of our Experimental section. A cylindrical shell (oven source) acquisition configuration is described in reference 3, where the authors disclosed this configuration to gain improved sensitivity for holdup measure of U-235 in a ten-chamber oven. The oven was a piece of process equipment used in the Savannah River Plant M-Area Uranium Fuel Fabrication plant for which a U-235 holdup measurement was necessary for its decontamination and decommissioning in 2003.4 In reference 4 the authors calibrated a bare NaI detector for these U-235 holdup measurements. In references 5 and 6 the authors calibrated a bare HpGe detector in a cylindrical shell configuration for improved sensitivity measurements of U-235 in other M-Area process equipment. Sensitivity was vastly improved compared to a close field view of the sample, with detection efficiency of greater than 1% for the 185.7-keV {gamma}-ray from U-235. In none of references 3 - 7 did the authors resolve the exact calculus descriptions of the acquisition configurations. Only the empirical efficiency for detection of the 185.7-keV photon from U-235 decay was obtained. Not until the 2010 paper of reference 1 did the authors derive a good theoretical description of the flux of photons onto the front face of a detector from an axially symmetric cylindrical shell. Subsequent to publication of 1, the theoretical treatment of the cylindrical shell and disk source acquisition sources was recognized by the Los Alamos National Laboratory as suitable for including in the Safeguards Training Program.8 Therefore, we felt it was important to accurately demonstrate the calculus describing the cylindrical shell configuration for the HpGe detector and to theoretically account for the observed bare-detector efficiencies measured in references (3-6). In this paper we demonstrate the applicability of the cylindrical shell derivation to a flexible planar sheet of known Am-241, Eu-152, and Cs-137 activity that we rolled into a symmetrical cylindrical shell of radioactivity. Using the geometry correction equation of reference 1, we calculate geometry correction values using the known detector and source dimensions combined with source to detector distances. We then compare measured detection efficiencies from a cylindrical shell of activity for the 185.7-keV photon (U-235) and for the 414.3-keV photon (Pu-239) with those determined for a 12-inch point source(2,7) to demonstrate agreement between experiment and the theoretically calculated values derived by the Savannah River National Laboratory (SRNL) authors of reference 1. We demonstrate this geometry correction first for the 185.7- and 414.3-keV {gamma}-rays. But because the detector was point source calibrated at 12 inches for the energy range (60 -1700) keV (using two distinct sources) to map its intrinsic efficiency, the geometry correction for any acquisition configuration holds for all photon energies.2 We demonstrate that for ten photon energies in the range 121 keV to 967 keV. The good agreement between experiment and calculation is demonstrated at five source to detector distances using the identical shielded HpGe detector of references 4-7 as well as with a separate HpGe detector. We then extend the measurement to include a single acquisition where the flexible source is wrapped around the bare detector in a symmetrical cylinder tha
Measurement of the Charge Collection Efficiency after Heavy Non-Uniform Irradiation in BaBar Silicon Detectors
Bettarini, S; Bosisio, L; Calderini, G; Campagnari, C; Dittongo, S; Forti, F; Giorgi, M A; Marchiori, G; Rizzo, G
We have investigated the depletion voltage changes, the leakage current increase and the charge collection efficiency of a silicon microstrip detector identical to those used in the inner layers of the BaBar Silicon Vertex Tracker (SVT) after heavy non-uniform irradiation. A full SVT module with the front-end electronics connected has been irradiated with a 0.9 GeV electron beam up to a peak fluence of 3.5 x 10^14 e^-/cm^2, well beyond the level causing substrate type inversion. We irradiated one of the two sensors composing the module with a non-uniform profile with sigma=1.4 mm that simulates the conditions encountered in the BaBar experiment by the modules intersecting the horizontal machine plane. The position dependence of the charge collection properties and the depletion voltage have been investigated in detail using a 1060 nm LED and an innovative measuring technique based only on the digital output of the chip.
Modulation transfer function and detective quantum efficiency of electron bombarded charge coupled device detector for low energy electrons
Horacek, Miroslav [Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, Kralovopolska 147, CZ-61264 Brno (Czech Republic)
The use of a thinned back-side illuminated charge coupled device chip as two-dimensional sensor working in direct electron bombarded mode at optimum energy of the incident signal electrons is demonstrated and the measurements of the modulation transfer function (MTF) and detective quantum efficiency (DQE) are described. The MTF was measured for energy of electrons 4 keV using an edge projection method and a stripe projection method. The decrease of the MTF for a maximum spatial frequency of 20.8 cycles/mm, corresponding to the pixel size 24x24 {mu}m, is 0.75{approx_equal}-2.5 dB, and it is approximately the same for both horizontal and vertical directions. DQE was measured using an empty image and the mixing factor method. Empty images were acquired for energies of electrons from 2 to 5 keV and for various doses, ranging from nearly dark image to a nearly saturated one. DQE increases with increasing energy of bombarded electrons and reaches 0.92 for electron energy of 5 keV. For this energy the detector will be used for the angle- and energy-selective detection of signal electrons in the scanning low energy electron microscope.
Low ? activity measurement of meteorites using HPGe-NaI detector system
NASA Astrophysics Data System (ADS)
Colombetti, P.; Taricco, C.; Bhandari, N.; Sinha, N.; Di Martino, M.; Cora, A.; Vivaldo, G.
The radioactivity in natural samples like cosmogenic isotopes in meteorites, in Moon samples, in earth and ice in Antarctica, produced by protons, neutrons, ? mesons and other charged particles, is very low, usually below 0.001 disintegration per minute per gram. Therefore, very special techniques are required, particularly if the sample cannot be destroyed for chemical separation and system must have possibility of counting large amount of sample. For this purpose we have developed a highly selective Ge-NaI coincidence spectrometer, operating in the underground Laboratory of Monte dei Cappuccini (INAF) in Torino. We have then improved it by developing a multiparametric acquisition system, which allows better selectivity of the coincidence windows (e.g., in meteorites, to disentangle cosmogenic 44Ti signal from overlapping 214Bi, originated by naturally occurring 238U). Applications of this system to the study of meteorites (chondrite, achondrite and iron samples) are described.
Systematic Effects in Pulse Shape Analysis of HPGe Detector Signals for Neutrinoless Double-Beta Decay
Victor M Gehman; Steven R Elliott; Dongming Mei
Pulse shape analysis is an important background reduction and signal\\u000aidentification technique for next generation of neutrinoless double-beta decay\\u000aexperiments examining 76Ge. We present a study of the systematic uncertainties\\u000ain one such parametric pulse-shape analysis technique for separating multi-site\\u000abackgrounds from single-site signal events. We examined systematic\\u000auncertainties for events in full-energy gamma peaks (predominantly multi-site),\\u000adouble escape peaks
Systematic Effects in Pulse Shape Analysis of HPGe Detector Signals for Neutrinoless Double-Beta Decay
Victor M Gehman; Steven R Elliott; Dongming Mei
Pulse shape analysis is an important background reduction and signal identification technique for next generation of neutrinoless double-beta decay experiments examining 76Ge. We present a study of the systematic uncertainties in one such parametric pulse-shape analysis technique for separating multi-site backgrounds from single-site signal events. We examined systematic uncertainties for events in full-energy gamma peaks (predominantly multi-site), double escape peaks (predominantly single-site) and the Compton continuum near double-beta decay endpoint (which will be the dominant background for most neutrinoless double-beta decay searches). In short, we find total (statistical plus systematic) fractional uncertainties in the pulse shape cut survival probabilities of: 6.6%, 1.5% and 3.8% for double-escape, continuum and gamma-ray events respectively.
New fission mode of the 252Cf spontaneous fission obtained with modern HPGE detectors
NASA Astrophysics Data System (ADS)
Daniel, A. V.; Ter-Akopian, G. M.; Hamilton, J. H.; Oganessian, Yu. Ts.; Kormicki, J.; Popeko, G. S.; Ramayya, A. V.; Ma, W.-C.; Babu, B. R. S.; Ginter, T.; Zhu, S. J.; Rasmussen, J.; Stoyer, M. A.; Lee, I. Y.; Asztalos, S.; Chu, S. Y.; Gregorich, K. E.; Macchiavelli, A. O.; Mohar, M. F.; Prussin, S. G.; Kliman, J.; Morhac, M.; Cole, J. D.; Aryaeinejad, R.; Dardenne, Y. K.; Driger, M.
The data of Independent yields of secondary fission fragment pairs (emerging after prompt neutron emission from primary fragment pairs) obtained by detecting coincidences between ? rays following the spontaneous fission of 252Cf have been expanded. Our approach to estimate characteristics of the primary fragments pairs (mass and excitation energy distributions) by unfolding the yields of secondary fragment pairs is discussed. Mew model parameters were introduced and results are presented here. The new results confirmed our old assumption that in case of Mo-Ba charge split the two fission modes differing with average total kinetic energy
Scoping measurements of radionuclides in L Lake with an underwater HPGe detector
D. L. Dunn; W. G. Win; P. J. Bresnahan
This study of L Lake was conducted to determine whether the distribution of man-made radiation levels had changed from the time preceding the filling of the newly created lake in 1985. Overflight gamma measurements by EG&G in 1985 mapped the man-made radiation levels, indicating that significant levels were only detected from former stream beds that were to be covered by
KMESS: An open source software package using a semi-empirical mesh-grid method for the modeling of germanium detector efficiencies
NASA Astrophysics Data System (ADS)
Jackman, Kevin Richard
Traditional approaches in gamma-ray spectroscopy for determining the absolute full-energy peak efficiencies of germanium detectors are primarily either too time consuming or not economically viable. In addition, these approaches are difficult to use for arbitrary source shapes and counting geometries. An open source software package, KMESS (Kevin's Mesh Efficiency Simulator Software), was developed to address these problems. KMESS uses a new semi-empirical mesh-grid method to predict the absolute full-energy peak efficiencies of n- and p-type germanium detectors in both coaxial and closed-ended configurations. The model assumes that any gamma-ray source shape can be treated as a collection of point sources. The code was written in a modular form, making it easy to adapt for other detector configurations and materials. A suite of web-based graphical front-end tools was also developed to make the execution of KMESS user-friendly. KMESS can predict most full-energy peak efficiencies to within 10% accuracy for the energy range 100--1800 keV in less than 10 minutes.
Cascaded-systems analyses and the detective quantum efficiency of single-Z x-ray detectors including photoelectric, coherent and incoherent interactions
Yun, Seungman [Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, 100 Perth Drive, London, Ontario N6A 5K8 (Canada); School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Tanguay, Jesse; Cunningham, Ian A. [Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, 100 Perth Drive, London, Ontario N6A 5K8 (Canada); Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)
Purpose: Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper describes an extension of the CSA approach to incorporate coherent and incoherent interactions, important for low-Z detectors such as silicon and selenium. Methods: A parallel-cascade approach is used to describe the three types of x-ray interactions. The description of incoherent scatter required developing expressions for signal and noise transfer through an 'energy-labeled reabsorption' process where the parameters describing reabsorption are random functions of the scatter photon energy. The description of coherent scatter requires the use of scatter form factors that may not be accurate for some crystalline detector materials. The model includes the effects of scatter reabsorption and escape, charge collection, secondary quantum sinks, noise aliasing, and additive noise. Model results are validated by Monte Carlo calculations for Si and Se detectors assuming free-atom atomic form factors. Results: The new signal and noise transfer expressions were validated by showing agreement with Monte Carlo results. Coherent and incoherent scatter can degrade the DQE of Si and sometimes Se detectors depending on detector thickness and incident-photon energy. Incoherent scatter can produce a substantial low-frequency drop in the modulation transfer function and DQE. Conclusions: A generally useful CSA model of the DQE is described that is believed valid for any single-Z material up to 10 cycles/mm at both mammographic and radiographic energies within the limitations of Fourier-based linear-systems models and the use of coherent-scatter form factors. The model describes a substantial low-frequency drop in the DQE of Si systems due to incoherent scatter above 20-40 keV.
Spectral sensitivity, quantum efficiency, and noise equivalent power of NbN superconducting single-photon detectors in the IR range
I. Rubtsova; A. Korneev; V. Matvienko; G. Chulkova; I. Milostnaya; G. Goltsman; A. Pearlman; W. Slysz; A. Verevkin; R. Sobolewski
We have developed nanostructured NbN superconducting single-photon detectors capable of GHz-rate photon counting in the 0.4 to 5 ?m wavelength range. Quantum efficiency of 30%, dark count rate 3�10-4 s-1, and NEP=10-20 W\\/Hz-12\\/ have been measured at the 1.3-?m wavelength for the device operating at 2.0 K.
A digital signal processing based bit synchronizer and novel hardware efficient lock detector circuit for bi-phase data for Chandrayaan-1 mission
Satish Sharma; Sunil Kulkarni; VijayKumar Pujari; P. Lakshimnarsimhan
The paper presents hardware efficient design of digital signal processing (DSP) based bit synchronizer and lock detector circuit for bi-phase data. The system is developed for one of the payload of Chandrayaan-I mission, and tested for its performance. Apart from the implementation, paper describes the mathematical modeling of bit synchronizer. The whole design is accommodated in a single Actel-1280 FPGA.
Neutrino Detectors: Challenges and Opportunities
Soler, F. J. P. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
This paper covers possible detector options suitable at future neutrino facilities, such as Neutrino Factories, Super Beams and Beta Beams. The Magnetised Iron Neutrino Detector (MIND), which is the baseline detector at a Neutrino Factory, will be described and a new analysis which improves the efficiency of this detector at low energies will be shown. Other detectors covered include the Totally Active Scintillating Detectors (TASD), particularly relevant for a low energy Neutrino Factory, emulsion detectors for tau detection, liquid argon detectors and megaton scale water Cherenkov detectors. Finally the requirements of near detectors for long-baseline neutrino experiments will be demonstrated.
Operation of a GERDA Phase I prototype detector in liquid argon and nitrogen
M. Barnab� Heider; A. Bakalyarov; L. Bezrukov; C. Cattadori; O. Chkvorets; K. Gusev; M. Hult; I. Kirpichnikov; V. Lebedev; G. Marissens; P. Peiffer; S. Sch�nert; M. Shirchenko; A. Smolnikov; A. Vasenko; S. Vasiliev; S. Zhukov
The GERDA (GERmanium Detector Array) experiment aiming to search for the neutrinoless double beta decay of 76Ge at the Laboratori Nazionali Del Gran Sasso (LNGS), Italy, will operate bare enriched high-purity germanium (HPGe) detectors in liquid argon. GERDA Phase I will use the enriched diodes from the previous Heidelberg-Moscow (HdM) and IGEX experiments. With the HPGe detectors mounted in a low-mass holder, GERDA aims at an excellent energy resolution and extremely low background. The goal is to check the claim for the neutrinoless double beta decay evidence in the HdM 76Ge experiment within one year of data taking. Before dismounting the enriched diodes from their cryostat, the performance parameters of the HdM and the IGEX detectors have been measured. The diodes have been removed from their cryostats, their dimensions measured and they have been put under va-cuum in a transportation container. They are now being refurbished for GERDA Phase I at Canberra Semiconductor NV. Before operating the enriched diodes, a non-enriched HPGe p-type detector mounted in a low-mass holder is operated in the liquid argon test facility of the GERDA Detector Laboratory (GDL) at LNGS. Since January 2006, the testing of the prototype detector is being carried out in the GDL as well as at the site of the detector manufacturer.
Measurement of gamow-teller strength for 176Yb --> 176Lu and the efficiency of a solar neutrino detector
Bhattacharya; Goodman; Raghavan; Palarczyk; Garcia; Rapaport; van Heerden IJ; Zupranski
We report a 0 degrees 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine Gamow-Teller (GT) matrix elements relative to the model independent Fermi matrix element. The data show that there is an isolated concentration of GT strength in the low-lying 1(+) states making the proposed Low Energy Neutrino Spectroscopy detector (based on neutrino captures on 176Yb) sensitive to pp and 7Be neutrinos and a promising detector to resolve the solar neutrino problem. PMID:11082567
A Measurement of Gamow-Teller Strength for 176Yb -> 176Lu and the Efficiency of a Solar Neutrino Detector
M. Bhattacharya; C. D. Goodman; R. S. Raghavan; M. Palarczyk; A. Garcia; J. Rapaport; I. J. van Heerden; P. Zupranski
We report a 0-degree 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine GT matrix elements relative to the Fermi matrix element which can be calculated model independently. The data show that there is an isolated concentration of GT strength in the low lying 1+ states making the proposed Low Energy Neutrino Spectroscopy (LENS) detector (based on neutrino captures on 176Yb) sensitive to 7Be and pp neutrinos and a promising detector to resolve the solar neutrino problem.
K114 (trans, trans)-bromo-2,5-bis(4-hydroxystyryl)benzene is an efficient detector of cationic amyloid fibrils.
Selmani, Veli; Robbins, Kevin J; Ivancic, Valerie A; Lazo, Noel D
Cationic amyloid fibrils found in human semen enhance the transmission of the human immunodeficiency virus (HIV) and thus, are named semen-derived enhancer of virus infection (SEVI). The mechanism for the enhancement of transmission is not completely understood but it has been proposed that SEVI neutralizes the repulsion that exists between the negatively charged viral envelope and host cell membrane. Consistent with this view, here we show that the fluorescence of cationic thioflavin T (ThT) in the presence of SEVI is weak, and thus ThT is not an efficient detector of SEVI. On the other hand, K114 ((trans, trans)-bromo-2,5-bis(4-hydroxystyryl)benzene) forms a highly fluorescent, phenolate-like species on the cationic surface of SEVI. This species does not form in the presence of amyloid fibrils from insulin and amyloid-? protein, both of which are efficiently detected by ThT fluorescence. Together, our results show that K114 is an efficient detector of SEVI. PMID:25524064
Small Scale Assessment of Spatial and Vertical Redistribution of Fukushima Fallouts Radiocaesium in Contaminated Soil Using in-situ HPGe Gamma Ray Spectrometry
NASA Astrophysics Data System (ADS)
Patin, J.; Onda, Y.; Yoda, H.; Kato, H.
After Tohoku earthquake on March 11th 2011, the subsequent tsunami and the resulting Fukushima Daiichi Nuclear Power Plant disaster, gamma emitting particles, first release into the atmosphere, were quickly deposited on the soil surface, with potentially harmful level in the surroundings of the nuclear power plant. Thus, the evaluation of soil deposition pattern, depth migration and afterward radionuclides redistribution and export by erosion and hydrological processes is fundamental for contamination assessments and to plan future actions. Our study site is located 37km from Fukushima power plant, inside the evacuated zone. In this study, we used a bounded erosion plot of 22.1m x 5m to assess global export of sediments and 137Cs. This plot, previously cropped with tobacco, is morphologically divided into inter-rill areas separated by rills that formed into former wheel tracks. The bottom of the plot is subject to deposition of sediments. In order to determine and quantify the internal processes responsible of the export of sediment, the depth distribution of 137Cs is estimated using a portable High Purity Germanium (HPGe) detector. Such a portable device, associated to the high radiation levels, allow an acquisition of spatially distributed data within the plot in a reasonable time (1 min/sample). At the same time, depth distribution of 137Cs are measured using the scrapper plate technique, adapted to obtain a fine resolution in the first, highly contaminated, centimeters of soil. Finally, 137Cs depth profiles, associated with in situ and laboratory gamma spectrums acquired with the portable detector, allow for the detector calibration. Although the initial deposit can reasonably be supposed homogeneous at the plot scale, the dataset obtained 3 months later shows high spatial and temporal variability due to erosion processes. Measurements with the portable HPGe detector proved to be useful at this small scale, avoiding the needs of a large number of soil samples, and our results are promising to understand erosion at larger scale where horizontal patterns of deposition and redistribution are usually supposed homogeneous over quite larger areas.
Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications
Rosenberg, M. J.; Seguin, F. H.; Waugh, C. J.; Rinderknecht, H. G.; Orozco, D.; Frenje, J. A.; Johnson, M. Gatu; Sio, H.; Zylstra, A. B.; Sinenian, N.; et al
CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ~0.5�8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 �C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7�4.3-MeV protons and established that for 2.4-MeV protons, relevant formore��detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ?3 � 106 cm�2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ~50, increasing the operating yield upper limit by a comparable amount.��less
Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications
Rosenberg, M. J.; Seguin, F. H.; Waugh, C. J.; Rinderknecht, H. G.; Orozco, D.; Frenje, J. A.; Johnson, M. Gatu; Sio, H.; Zylstra, A. B.; Sinenian, N.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Stoeckl, C.; Hohenberger, M.; Sangster, T. C.; LePape, S.; Mackinnon, A. J.; Bionta, R. M.; Landen, O. L.; Zacharias, R. A.; Kim, Y.; Herrmann, H. W.; Kilkenny, J. D.
CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ~0.5�8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 �C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7�4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ?3 � 106 cm�2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ~50, increasing the operating yield upper limit by a comparable amount.
Detectors in astronomy - Infrared astronomy
E. T. Young
The technical characteristics of infrared detectors are discussed. The mode of operation of thermal, photovoltaic, and photoconductive detectors is explained, and for each type, the noise equivalent power and quantum efficiency are assessed. The influence of doping is discussed; the Ga-doped Ge bolometer is a virtually ideal detector with almost unity quantum efficiency. At wavelengths below five microns, the most
Analytical modeling of relative luminescence efficiency of Al2O3:C optically stimulated luminescence detectors exposed to high-energy heavy charged particles
NASA Astrophysics Data System (ADS)
Sawakuchi, Gabriel O.; Yukihara, Eduardo G.
The objective of this work is to test analytical models to calculate the luminescence efficiency of Al2O3:C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytical expression for the relative luminescence efficiency based on the average radial dose distribution produced by the heavy charged particle. We compared the relative luminescence efficiency calculated using seven different radial dose distribution models, including a modified model introduced in this work, with experimental data. The results obtained using the modified radial dose distribution function agreed within 20% with experimental data from Al2O3:C OSLDs relative luminescence efficiency for particles with atomic number ranging from 1 to 54 and linear energy transfer in water from 0.2 up to 1368 keV �m-1. In spite of the significant improvement over other radial dose distribution models, understanding of the underlying physical processes associated with these radial dose distribution models remain elusive and may represent a limitation of the track structure model.
Analytical modeling of relative luminescence efficiency of Al2O3:C optically stimulated luminescence detectors exposed to high-energy heavy charged particles.
Sawakuchi, Gabriel O; Yukihara, Eduardo G
The objective of this work is to test analytical models to calculate the luminescence efficiency of Al(2)O(3):C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytical expression for the relative luminescence efficiency based on the average radial dose distribution produced by the heavy charged particle. We compared the relative luminescence efficiency calculated using seven different radial dose distribution models, including a modified model introduced in this work, with experimental data. The results obtained using the modified radial dose distribution function agreed within 20% with experimental data from Al(2)O(3):C OSLDs relative luminescence efficiency for particles with atomic number ranging from 1 to 54 and linear energy transfer in water from 0.2 up to 1368 keV �m(-1). In spite of the significant improvement over other radial dose distribution models, understanding of the underlying physical processes associated with these radial dose distribution models remain elusive and may represent a limitation of the track structure model. PMID:22173080
Advanced UV Detectors and Detector Arrays
NASA Technical Reports Server (NTRS)
Pankove, Jacques I.; Torvik, John
Gallium Nitride (GaN) with its wide energy bandgap of 3.4 eV holds excellent promise for solar blind UV detectors. We have successfully designed, fabricated and tested GaN p-i-n detectors and detector arrays. The detectors have a peak responsivity of 0.14A/W at 363 nm (3.42 eV) at room temperature. This corresponds to an internal quantum efficiency of 56%. The responsivity decreases by several orders of magnitude to 0.008 A/W at 400 nm (3.10 eV) giving the excellent visible rejection ratio needed for solar-blind applications.
Study of the material photon and electron background and the liquid argon detector veto efficiency of the CDEX-10 experiment
NASA Astrophysics Data System (ADS)
Su, Jian; Zeng, Zhi; Ma, Hao; Yue, Qian; Cheng, Jian-Ping; Chang, Jian-Ping; Chen, Nan; Chen, Ning; Chen, Qing-Hao; Chen, Yun-Hua; Chuang, Yo-Chun; Deng, Zhi; Du, Qiang; Gong, Hui; Hao, Xi-Qing; He, Qing-Ju; Huang, Han-Xiong; Huang, Teng-Rui; Jiang, Hao; Kang, Ke-Jun; Li, Hau-Bin; Li, Jian-Min; Li, Jin; Li, Jun; Li, Xia; Li, Xin-Ying; Li, Xue-Qian; Li, Yu-Lan; Li, Yuan-Jing; Liao, Heng-Yi; Lin, Fong-Kay; Lin, Shin-Ted; Liu, Shu-Kui; L�, Lan-Chun; Mao, Shao-Ji; Qin, Jian-Qiang; Ren, Jie; Ren, Jing; Ruan, Xi-Chao; Shen, Man-Bin; Lakhwinder, Singh; Manoj, Kumar Singh; Arun, Kumar Soma; Tang, Chang-Jian; Tseng, Chao-Hsiung; Wang, Ji-Min; Wang, Li; Wang, Qing; Wong Tsz-King, Henry; Wu, Shi-Yong; Wu, Yu-Cheng; Xing, Hao-Yang; Xu, Yin; Xue, Tao; Yang, Li-Tao; Yang, Song-Wei; Yi, Nan; Yu, Chun-Xu; Yu, Hao; Yu, Xun-Zhen; Zeng, Xiong-Hui; Zhang, Lan; Zhang, Yun-Hua; Zhao, Ming-Gang; Zhao, Wei; Zhou, Zu-Ying; Zhu, Jing-Jun; Zhu, Wei-Bin; Zhu, Xue-Zhou; Zhu, Zhong-Hua; CDEX collaboration
The China Dark Matter Experiment (CDEX) is located at the China Jinping Underground Laboratory (CJPL) and aims to directly detect the weakly interacting massive particles (WIMP) flux with high sensitivity in the low mass region. Here we present a study of the predicted photon and electron backgrounds including the background contribution of the structure materials of the germanium detector, the passive shielding materials, and the intrinsic radioactivity of the liquid argon that serves as an anti-Compton active shielding detector. A detailed geometry is modeled and the background contribution has been simulated based on the measured radioactivities of all possible components within the GEANT4 program. Then the photon and electron background level in the energy region of interest (<10?2events�kg1�day?1�keV?1 (cpkkd)) is predicted based on Monte Carlo simulations. The simulated result is consistent with the design goal of the CDEX-10 experiment, 0.1cpkkd, which shows that the active and passive shield design of CDEX-10 is effective and feasible. Supported by National Natural Science Foundation of China (11175099, 10935005, 10945002, 11275107, 11105076) and State Key Development Program of Basic Research of China (2010CB833006)
Strategy of HPGe screening measurements in the SuperNEMO experiment
Perrot, Fr�d�ric [Universit� de Bordeaux, Centre d'Etudes Nucl�aires de Bordeaux Gradignan, UMR 5797, Chemin du Solarium, Le Haut-Vigneau, BP120, F-33175 Gradignan, France and CNRS/IN2P3, Centre d'Etudes Nucl�aires de Bordeaux Gradignan, UMR 5797 (France)] [Universit� de Bordeaux, Centre d'Etudes Nucl�aires de Bordeaux Gradignan, UMR 5797, Chemin du Solarium, Le Haut-Vigneau, BP120, F-33175 Gradignan, France and CNRS/IN2P3, Centre d'Etudes Nucl�aires de Bordeaux Gradignan, UMR 5797 (France); Collaboration: SuperNEMO Collaboration
SuperNEMO is a double beta decay experiment that will use a tracko-calorimeter technique. The goal is to reach a sensitivity of T{sub 1/2}(0?)>10{sup 26} y corresponding to an effective Majorana neutrino mass of 0.04-0.11 eV with 100 kg of {sup 82}Se. The general strategy of the HPGe screening measurements is described for the materials of the SuperNEMO demonstrator, regarding their radiopurity and their location. The two platforms, PRISNA and LSM, used for this screening are also briefly described.
Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors
NASA Astrophysics Data System (ADS)
Lusche, R.; Semenov, A.; Ilin, K.; Siegel, M.; Korneeva, Y.; Trifonov, A.; Korneev, A.; Goltsman, G.; Vodolazov, D.; H�bers, H.-W.
A thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths has been performed. The experiment shows that the cut-off of the intrinsic detection efficiency at near-infrared wavelengths is most likely controlled by the local suppression of the barrier for vortex nucleation around the absorption site. Beyond the cut-off quasi-particle diffusion in combination with spontaneous, thermally activated vortex crossing explains the detection process. For both materials, the reciprocal cut-off wavelength scales linearly with the wire width where the scaling factor agrees with the hot-spot detection model.
Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors
Lusche, R., E-mail: email@example.com; Semenov, A. [Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstr. 2, 12489 Berlin (Germany); Ilin, K.; Siegel, M. [Institute of Micro- und Nano-electronic Systems (IMS), KIT, Hertzstrasse 16, 76187 Karlsruhe (Germany); Korneeva, Y.; Trifonov, A. [Department of Physics, Moscow State Pedagogical University, 1 Malaya Pirogovskaya, 119991 Moscow (Russian Federation); Korneev, A. [Department of Physics, Moscow State Pedagogical University, 1 Malaya Pirogovskaya, 119991 Moscow (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya Ulitsa, Moscow 101000 (Russian Federation); Moscow Institute of Physics and Technology (State University), 9 Institutskiy pereulok, Dolgoprudny, Moscow region 141700 (Russian Federation); Goltsman, G. [Department of Physics, Moscow State Pedagogical University, 1 Malaya Pirogovskaya, 119991 Moscow (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya Ulitsa, Moscow 101000 (Russian Federation); Vodolazov, D. [Institute for Physics of Microstructures, Russian Academy of Sciences, 603950 Nizhny Novgorod, GSP-105 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603950 Nizhny Novgorod (Russian Federation); H�bers, H.-W. [Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstr. 2, 12489 Berlin (Germany); Institut f�r Optik und Atomare Physik, Technische Universit�t Berlin, Stra�e des 17. Juni 135, 10623 Berlin (Germany)
A thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths has been performed. The experiment shows that the cut-off of the intrinsic detection efficiency at near-infrared wavelengths is most likely controlled by the local suppression of the barrier for vortex nucleation around the absorption site. Beyond the cut-off quasi-particle diffusion in combination with spontaneous, thermally activated vortex crossing explains the detection process. For both materials, the reciprocal cut-off wavelength scales linearly with the wire width where the scaling factor agrees with the hot-spot detection model.
Segmented crystalline scintillators: empirical and theoretical investigation of a high quantum efficiency EPID based on an initial engineering prototype CsI(TI) detector.
Sawant, Amit; Antonuk, Larry E; El-Mohri, Youcef; Zhao, Qihua; Wang, Yi; Li, Yixin; Du, Hong; Perna, Louis
Modern-day radiotherapy relies on highly sophisticated forms of image guidance in order to implement increasingly conformal treatment plans and achieve precise dose delivery. One of the most important goals of such image guidance is to delineate the clinical target volume from surrounding normal tissue during patient setup and dose delivery, thereby avoiding dependence on surrogates such as bony landmarks. In order to achieve this goal, it is necessary to integrate highly efficient imaging technology, capable of resolving soft-tissue contrast at very low doses, within the treatment setup. In this paper we report on the development of one such modality, which comprises a nonoptimized, prototype electronic portal imaging device (EPID) based on a 40 mm thick, segmented crystalline CsI(Tl) detector incorporated into an indirect-detection active matrix flat panel imager (AMFPI). The segmented detector consists of a matrix of 160 x 160 optically isolated, crystalline CsI(Tl) elements spaced at 1016 microm pitch. The detector was coupled to an indirect detection-based active matrix array having a pixel pitch of 508 microm, with each detector element registered to 2 x 2 array pixels. The performance of the prototype imager was evaluated under very low-dose radiotherapy conditions and compared to that of a conventional megavoltage AMFPI based on a Lanex Fast-B phosphor screen. Detailed quantitative measurements were performed in order to determine the x-ray sensitivity, modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE). In addition, images of a contrast-detail phantom and an anthropomorphic head phantom were also acquired. The prototype imager exhibited approximately 22 times higher zero-frequency DQE (approximately 22%) compared to that of the conventional AMFPI (approximately 1%). The measured zero-frequency DQE was found to be lower than theoretical upper limits (approximately 27%) calculated from Monte Carlo simulations, which were based solely on the x-ray energy absorbed in the detector-indicating the presence of optical Swank noise. Moreover, due to the nonoptimized nature of this prototype, the spatial resolution was observed to be significantly lower than theoretical expectations. Nevertheless, due to its high quantum efficiency (approximately 55%), the prototype imager exhibited significantly higher DQE than that of the conventional AMFPI across all spatial frequencies. In addition, the frequency-dependent DQE was observed to be relatively invariant with respect to the amount of incident radiation, indicating x-ray quantum limited behavior. Images of the contrast-detail phantom and the head phantom obtained using the prototype system exhibit good visualization of relatively large, low-contrast features, and appear significantly less noisy compared to similar images from a conventional AMFPI. Finally, Monte Carlo-based theoretical calculations indicate that, with proper optimization, further, significant improvements in the DQE performance of such imagers could be achieved. It is strongly anticipated that the realization of optimized versions of such very high-DQE EPIDs would enable megavoltage projection imaging at very low doses, and tomographic imaging from a "beam's eye view" at clinically acceptable doses. PMID:16696482
Measurement and calculation of the efficiency of fission detectors designed to monitor the time dependence of the neutron production of JET
NASA Astrophysics Data System (ADS)
Swinhoe, M. T.; Jarvis, O. N.
Three pairs of fission counters (each pair one 235U and one 238U) are used at the Joint European Torus to determine the time dependence of the neutron production. In order to determine the absolute value of the neutron flux at the detector location it is necessary to know the neutron detection efficiency of the counter assemblies. This was measured using monoenergetic neutrons (at 2.5 and 14 MeV) and Cf and Am/Be sources. The fraction of fissions detected was determined by extrapolation of the pulse-height spectrum to zero pulse height. The calculation of efficiency was made with the Monte-Carlo neutron transport code MORSE. It was found that the detailed structure of the counter significantly affected the calculated efficiency and that the thermal cross-section values of the DLC37F nuclear data library had to be replaced with room-temperature values. The mean difference between calculation and experiment is (5.5�6.3)%.
Development of high quantum efficiency, flat panel, thick detectors for megavoltage x-ray imaging: a novel direct-conversion design and its feasibility.
Pang, G; Rowlands, J A
Most electronic portal imaging devices (EPIDs) developed to date, including recently developed flat panel systems, have low x-ray absorption, i.e., low quantum efficiency (QE) of 2%-4% as compared to the theoretical limit of 100%. A significant increase of QE is desirable for applications such as a megavoltage cone-beam computed tomography (MVCT) and megavoltage fluoroscopy. However, the spatial resolution of an imaging system usually decreases significantly with an increase of QE. The key to the success in the design of a high QE detector is therefore to maintain the spatial resolution. Recently, we demonstrated theoretically that it is possible to design a portal imaging detector with both high QE and high resolution [see Pang and Rowlands, Med. Phys. 29, 2274 (2002)]. In this paper, we introduce such a novel design consisting of a large number of microstructured plates (made by, e.g., photolithographic patterning of evaporated or electroplated layers) packed together and aligned with the incident x rays. On each plate, microstrip charge collectors are focused toward the x-ray source to collect charges generated in the ionization medium (e.g., air or gas) surrounded by high-density materials that act as x-ray converters. The collected charges represent the x-ray image and can be read out by various means, including a two-dimensional (2-D) active readout matrix. The QE, spatial resolution, and sensitivity of the detector have been calculated. It has been shown that the new design will have a QE of more than an order of magnitude higher and a spatial resolution equivalent to that of flat panel systems currently used for portal imaging. The new design is also quantum noise limited down to very low doses (approximately 1-2 radiation pulses of the linear accelerator). PMID:15587653
Graf, N.A.; /SLAC
As the complexity and resolution of imaging detectors increases, the need for detailed simulation of the experimental setup also becomes more important. Designing the detectors requires efficient tools to simulate the detector response and reconstruct the events. We have developed efficient and flexible tools for detailed physics and detector response simulation as well as event reconstruction and analysis. The primary goal has been to develop a software toolkit and computing infrastructure to allow physicists from universities and labs to quickly and easily conduct physics analyses and contribute to detector research and development. The application harnesses the full power of the Geant4 toolkit without requiring the end user to have any experience with either Geant4 or C++, thereby allowing the user to concentrate on the physics of the detector system.
Preliminary uranium enrichment analysis results using cadmium zinc telluride detectors
Lavietes, A.D.; McQuaid, J.H. [Lawrence Livermore National Lab., CA (United States); Paulus, T.J. [EG& G ORTEC, Oak Ridge, TN (United States)
Lawrence Livermore National Laboratory (LLNL) and EG&G ORTEC have jointly developed a portable ambient-temperature detection system that can be used in a number of application scenarios. The detection system uses a planar cadmium zinc telluride (CZT) detector with custom-designed detector support electronics developed at LLNL and is based on the recently released MicroNOMAD multichannel analyzer (MCA) produced by ORTEC. Spectral analysis is performed using software developed at LLNL that was originally designed for use with high-purity germanium (HPGe) detector systems. In one application, the CZT detection system determines uranium enrichments ranging from less than 3% to over 75% to within accuracies of 20%. The analysis was performed using sample sizes of 200 g or larger and acquisition times of 30 min. The authors have demonstrated the capabilities of this system by analyzing the spectra gathered by the CZT detection system from uranium sources of several enrichments. These experiments demonstrate that current CZT detectors can, in some cases, approach performance criteria that were previously the exclusive domain of larger HPGe detector systems.
The effects of Doppler broadening and detector resolution on the performance of three-stage Compton cameras
Mackin, Dennis; Polf, Jerimy; Peterson, Steve; Beddar, Sam
Purpose: The authors investigated how the characteristics of the detectors used in a three-stage Compton camera (CC) affect the CC's ability to accurately measure the emission distribution and energy spectrum of prompt gammas (PG) emitted by nuclear de-excitations during proton therapy. The detector characteristics they studied included the material (high-purity germanium [HPGe] and cadmium zinc telluride [CZT]), Doppler broadening (DB), and resolution (lateral, depth, and energy). Methods: The authors simulated three-stage HPGe and CZT CCs of various configurations, detecting gammas from point sources with energies ranging from 0.511 to 7.12 MeV. They also simulated a proton pencil beam irradiating a tissue target to study how the detector characteristics affect the PG data measured by CCs in a clinical proton therapy setting. They used three figures of merit: the distance of closest approach (DCA) and the point of closest approach (PCA) between the measured and actual position of the PG emission origin, and the calculated energy resolution. Results: For CCs with HPGe detectors, DB caused the DCA to be greater than 3 mm for 14% of the 6.13 MeV gammas and 20% of the 0.511 MeV gammas. For CCs with CZT detectors, DB caused the DCA to be greater than 3 mm for 18% of the 6.13 MeV gammas and 25% of the 0.511 MeV gammas. The full width at half maximum (FWHM) of the PCA in the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\hat z\\end{equation*} \\end{document}z^ direction for HPGe and CZT detectors ranged from 1.3 to 0.4 mm for gammas with incident energy ranging from 0.511 to 7.12 MeV. For CCs composed of HPGe detectors, the resolution of incident gamma energy calculated by the CC ranged from 6% to 1% for gammas with true incident energies from 0.511 to 7.12 MeV. For CCs composed of CZT detectors, the resolution of gamma energy calculated by the CC ranged from 10% to 1% for gammas with true incident energies from 0.511 to 7.12 MeV. For HPGe and CZT CCs in which all detector effect were included, the DCA was less than 3 mm for 75% and 68% of the detected gammas, respectively, and restricting gammas to those having energy greater than 2.0 MeV increased these percentages to 83% and 77% for HPGe and CZT, respectively. Distributions of the true gamma origins and the PCA after detector characteristics had been included showed good agreement on beam range and some loss of resolution for the lateral profile of the PG emission. Characteristic energy lines were evident in the calculated gamma energy spectrum. Conclusions: The authors found the following: (1) DB is the dominant source of spatial and energy resolution loss in the CCs at all energy levels; (2) the largest difference in the spatial resolution of HPGe and CZT CCs is that the spatial resolution distributions of CZT have broader tails. The differences in the FWHM of these distributions are small; (3) the energy resolution of both HPGe and CZT three-stage CCs is adequate for PG spectroscopy; and (4) restricting the gammas to those having energy greater than 2.0 MeV can improve the achievable image resolution. PMID:23298111
A direct comparison of Ge and Si(Li) detectors in the 2--20 keV range
Rossington, C.S.; Giauque, R.D.; Jaklevic, J.M.
The spectral response of high purity Ge (HPGe) and lithium-drifted Si (Si(Li)) surface barrier detectors of similar geometry has been measured over a range of x-ray energies under identical experimental conditions. Detector characteristics such as spectral background, escape peak intensity, entrance window absorption, and energy resolution are presented and compared. Although these characteristic have been discussed in the literature previously, this paper represents an attempt to consolidate the information by making comparisons under equivalent experimental conditions for the two types of detectors. A primary goal of the study is a comparison of the two types of detectors for use in x-ray fluorescence applications.
PHAROS: A pluri-detector, high-resolution, analyser of radiometric properties of soil
C. Rigollet; R. J. de Meijer
PHAROS is a new type of core logger, designed to measure activity concentrations of 40K, 238U, 232Th and 137Cs in sediment and rock cores with a spatial resolution of a few centimetres along the core. PHAROS has been developed as a non-destructive alternative to the traditional slicing of cores into sub-samples and their analysis on an HPGe detector. The core
NASA Technical Reports Server (NTRS)
LaRue, Ross A.
This report documents fabrication and testing of 532nm optical detectors. Testing procedures included 532nm quantum efficiency, detector gain, and photon counting performance, in particular, photon counting efficiency. 532nm quantum efficiency was measured to be 36% to 39% for the detectors fabricated. Detectors with a GaAs APD anode had measured gains of 12,000 to 15,000 maximum. Photon counting efficiency for the detector with an APD anode was measured to be approximately 80% with a detector gain of 11,000. Measurements made on an identical detector, not fabricated under this contract, had a photon counting efficiency exceeding 90% with a gain of 13,000. A formula is derived in which the photon counting efficiency is determined by the system preamp noise and the peak single photon pulse height which is proportional to detector gain. This formula agrees well with the measured results and indicates that a detector gain of 15,000 is sufficient to provide a counting efficiency of 99.6%.
A simultaneous measurement of the $b$-tagging efficiency scale factor and the $t\\bar{t}$ Production Cross Section at the Collider Detector at Fermilab
Hussain, Nazim; /McGill U.
The ability to compare results between Monte Carlo and data is imperative in modern experimental high-energy physics analyses. The b-tagging efficiency Scale Factor (SF) allows for an accurate comparison of b quark identification in data samples and Monte Carlo. This thesis presents a simultaneous measurement of the SF for the SecVtx algorithm and the t{bar t} production cross section using 5.6 fb{sup -1} of p{bar p} collision data at {radical}s = 1.96 TeV collected by the Collider Detector at Fermilab (CDF) experiment. The t{bar t} cross section was measured to be 7.26 {+-} 0.47 pb, consistent with prior CDF analyses. The tight SF value was measured to be 0.925 {+-} 0.032 and the loose SF value was measured at 0.967 {+-} 0.033. These are the most precise SF SecVtx measurements to be performed at CDF to date.
Application of cadmium-zinc-telluride detectors in U-235 enrichment measurements
Ruhter, W.D.; Gunnink, R. [Lawrence Livermore National Lab., CA (United States). Nuclear Chemistry Div.
High-resolution, gamma- and x-ray spectrometry are used routinely in nuclear safeguards verification measurements of plutonium and uranium in the field. These measurements are mostly performed with high-purity germanium (HPGe) detectors, that require cooling to liquid-nitrogen temperatures, thus limiting their utility in field and unattended safeguards measurement applications. NaI scintillation detectors do not require cooling, but their moderate energy resolution (10% at 122 keV) is insufficient in most cases for reliable verification measurements. Semiconductor detectors that operate at room temperature, such as cadmium-zinc-telluride (CdZnTe) detectors, with energy resolution performance reaching 2.0% at 122 keV may complement HPGe detectors for certain safeguards verification applications. The authors used a 5x5x5 mm CdZnTe detector to measure U-235 enrichments ranging from 3% to 75%. They use a spectrum analysis technique that fits U-235, U-238, and U K x-ray response profiles to data in the 89- to 100-keV region of gamma-ray spectrum. From the relative magnitudes of the U-235 and U-238 profiles they determine the U-235 enrichment with an accuracy of about 10% with CdZnTe detectors.
An investigation of the performance of a coaxial HPGe detector operating in a magnetic resonance imaging field
L. J. Harkness; A. J. Boston; H. C. Boston; P. Cole; J. R. Cresswell; F. Filmer; M. Jones; D. S. Judson; P. J. Nolan; D. C. Oxley; J. A. Sampson; D. P. Scraggs; M. J. Slee; W. E. Bimson; G. J. Kemp; J. Groves; J. Headspith; I. Lazarus; J. Simpson; R. J. Cooper
Nuclear medical imaging modalities such as positron emission tomography and single photon emission computed tomography are used to probe physiological functions of the body by detecting gamma rays emitted from biologically targeted radiopharmaceuticals. A system which is capable of simultaneous data acquisition for nuclear medical imaging and magnetic resonance imaging is highly sought after by the medical imaging community. Such
ERIC Educational Resources Information Center
Guerin, David A.
Light-emitting diodes (LEDs) are described and three classroom experiments are given, one to prove the, low power requirements and efficiency of LEDs, an LED on-off detector circuit, and the third an LED photoelectric smoke detector. (BB)
Biopolymer mass spectrometer with cryogenic particle detectors
Damian Twerenbold
A novel type of biopolymer mass spectrometer is proposed for massive proteins, polypeptides and DNA-fragments by replacing standard ionizing detectors with cryogenic particle detectors. The detection efficiency in ionizing detectors decreases rapidly with increasing biopolymer mass owing to the biopolymer's decreasing velocity. Cryogenic particle detectors, however, record the total kinetic energy deposited by the accelerated biopolymer. In a given electric
NASA Technical Reports Server (NTRS)
Because the liquid hydrogen which NASA stores for the space shuttle engines is easily ignited, a hand held ultraviolet fire detector was developed by detector electronics under NASA contract. The system was commercialized by Detector Electronics for use in other hydrogen handling facilities. The detector sensors spot a hydrogen flame at 100 feet, show radiation levels and provide an aural fire alert.
Akerib, D S; Bedikian, S; Bernstein, A; Bolozdynya, A; Bradley, A; Cahn, S; Carr, D; Chapman, J J; Clark, K; Classen, T; Curioni, A; Dahl, C E; Dazeley, S; deViveiros, L; Dragowsky, M; Druszkiewicz, E; Fiorucci, S; Gaitskell, R J; Hall, C; Faham, C; Holbrook, B; Kastens, L; Kazkaz, K; Kwong, J; Lander, R; Leonard, D; Malling, D; Mannino, R; McKinsey, D N; Mei, D; Mock, J; Morii, M; Nikkel, J; Phelps, P; Shutt, T; Skulski, W; Sorensen, P; Spaans, J; Steigler, T; Svoboda, R; Sweany, M; Thomson, J; Tripathi, M; Walsh, N; Webb, R; White, J; Wolfs, F L H; Woods, M; Zhang, C
The LUX (Large Underground Xenon) detector is a two-phase xenon Time Projection Chamber (TPC) designed to search for WIMP-nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large ($>$1ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1 meter to be achieved in approximately two days and sustained for the duration of the testing period.
4{\\pi}{\\beta} (LS)-{\\gamma} (HPGe) Digital Coincidence System Based on Synchronous High-Speed Multichannel Data Acquisition
Chen, Jifeng; Liang, Juncheng; Liu, Jiacheng
A dedicated 4{\\pi}{\\beta} (LS)-{\\gamma} (HPGe)digital coincidence system has been developed in this work, which includes five acquisition channels. Three analog-to-digital converter (ADC) acquisition channels with an acquisition resolution of 8 bits and acquisition rate of 1GSPS (sample per second) are utilized to collect the signals from three Photo multiplier tubes (PMTs) which are adopted to detect {\\beta} decay, and two acquisition channels with an acquisition resolution of 16 bits and acquisition rate of 50MSPS are utilized to collect the signals from high-purity germanium (HPGe) which are adopted to detect {\\gamma} decay. In order to increase the accuracy of the coincidence system, all the five acquisition channels are synchronous within 500ps. The data collected by the five acquisition channels will be transmitted to the host PC through PCI bus and saved as a file. Off-line software is applied for the 4{\\pi}{\\beta} (LS)-{\\gamma} (HPGe) coincidence and data analysis as needed in practical application. W...
Gammasphere and Orruba:. Dual Detectors for Experimental Structure Studies
NASA Astrophysics Data System (ADS)
Ratkiewicz, A.; Cizewski, J. A.; Hardy, S.; Howard, M. E.; Manning, B.; Shand, C. M.; Pain, S. D.; Bardayan, D. W.; Mato�, M.; Blackmon, J. C.; Carpenter, M. P.; Lister, C. J.; Seweryniak, D.; Zhu, S.; Chipps, K. A.; Jones, K. L.; Kozub, R. L.; Peters, W. A.
An outstanding question in nuclear structure is the evolution of single-neutron strength in open-shell neutron-rich nuclei. In the near term, accelerated beams of 252Cf fission fragments will be available with the ATLAS facility at Argonne National Laboratory through the CARIBU initiative. To exploit these beams, the Oak Ridge Rutgers University Barrel Array (ORRUBA) of positionsensitive silicon strip detectors is being coupled to the Gammasphere array of Compton-suppressed HPGe detectors. ORRUBA will be supplemented with up to four annular arrays of silicon strip detectors at backward and forward angles. The realization of this effort will enable high resolution studies of single-neutron excitations populated in (d,p) and (d,t) reaction studies in inverse kinematics with open-shell 252Cf fission fragment beams through the coincident detection of ? rays and particles.
Gallium arsenide pixel detectors
NASA Astrophysics Data System (ADS)
Bates, R.; Campbell, M.; Cantatore, E.; D'Auria, S.; da Vi�, C.; del Papa, C.; Heijne, E. M.; Middelkamp, P.; O'Shea, V.; Raine, C.; Ropotar, I.; Scharfetter, L.; Smith, K.; Snoeys, W.
GaAs detectors can be fabricated with bidimensional single-sided electrode segmentation. They have been successfully bonded using flip-chip technology to the Omega-3 silicon read-out chip. We present here the design features of the GaAs pixel detectors and results from a test performed at the CERN SpS with a 120 GeV ?- beam. The detection efficiency was 99.2% with a nominal threshold of 5000 e -.
Evaluation of the efficiency of radioactive decontamination for alkyd and epoxy-urethane coating systems
NASA Astrophysics Data System (ADS)
Jevremovi?, Milutin; Milo�evi?, Bratislav; Lazarevi?, Nata�a
This article presents experimental results obtained by the investigation of the efficiency of radioactive decontamination of a metal surface with alkyd and epoxy-urethane coating systems, which are used for the painting of military equipment. During the evaluation of the efficiency of decontamination, the impact of contaminants on the coating was not examined but the amount of contaminants residual after decontamination was, and was determined by activity measurements of the surface. The samples for testing were painted aluminum plates contaminated by liquid solutions of radioactive isotopes 60Co, 133Ba, 152Eu and 241Am (A=12297.91 Bq/ml). Decontamination of contaminated samples was performed with 0.5% detergent solution on the basis of synthetic surfactants. The activity measurements of samples were conducted using gamma spectroscopy system with a high-resolution high-purity germanium (HPGe) detector of relative efficiency of 50% at 60Co (1.33 MeV). The degree of removal of the radioactivity on the samples was observed as an indicator of the efficiency of decontamination. A comparison of the results is presented in relation to the retention time of the contamination on the surface coating, which is an important factor for the efficiency of decontamination. The samples with an alkyd coating system showed better efficiency of decontamination than the samples with the epoxy-urethane coating system, although the coatings based on epoxy and urethane resin were superior in relation to the alkyd in terms of protection, decorative characteristics and chemical resistance. The difference in the efficiency of decontamination for the examined coatings increases almost linearly in relation to the retention time of the contaminants in the coating.
Layered semiconductor neutron detectors
Mao, Samuel S; Perry, Dale L
Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.
Calibration drift in a laboratory high purity germanium detector spectrometry system.
Dewey, S C; Kearfott, K J
For unknown radionuclide identification, it is important that a high purity germanium (HPGe) spectrometry system be calibrated correctly for energy. The energy calibration of an HPGe spectrometry system will drift over time due to a variety of factors including the ambient temperature, the line voltage applied to the system, variation in the electronics, and other possible influences. In order to better understand the nature of this energy calibration drift, calibration spectra were collected over a period of several months from a laboratory HPGe spectrometry system. System parameters, including detector voltage, amplifier gain, and preamplifier gain, were not deliberately modified during the course of the experiment. The system was calibrated routinely over the 90 days, and the results of the calibrations were compared in order to assess the drift in the energy calibration of the detector over time. The analysis of a 36% high purity germanium system demonstrated the energy calibration drifted an average of 0.014 keV d(-1) to 0.041 keV d(-1) depending upon energy. At 1,332 keV, one day after calibration, it was shown that up to half of the total error in energy calibration was as a result of calibration drift. PMID:18192795
NASA Astrophysics Data System (ADS)
Grupen, Claus; Shwartz, Boris
Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resum�; Appendixes; Index.
HIgh Rate X-ray Fluorescence Detector
Grudberg, Peter Matthew [XIA LLC
The purpose of this project was to develop a compact, modular multi-channel x-ray detector with integrated electronics. This detector, based upon emerging silicon drift detector (SDD) technology, will be capable of high data rate operation superior to the current state of the art offered by high purity germanium (HPGe) detectors, without the need for liquid nitrogen. In addition, by integrating the processing electronics inside the detector housing, the detector performance will be much less affected by the typically noisy electrical environment of a synchrotron hutch, and will also be much more compact than current systems, which can include a detector involving a large LN2 dewar and multiple racks of electronics. The combined detector/processor system is designed to match or exceed the performance and features of currently available detector systems, at a lower cost and with more ease of use due to the small size of the detector. In addition, the detector system is designed to be modular, so a small system might just have one detector module, while a larger system can have many �?? you can start with one detector module, and add more as needs grow and budget allows. The modular nature also serves to simplify repair. In large part, we were successful in achieving our goals. We did develop a very high performance, large area multi-channel SDD detector, packaged with all associated electronics, which is easy to use and requires minimal external support (a simple power supply module and a closed-loop water cooling system). However, we did fall short of some of our stated goals. We had intended to base the detector on modular, large-area detectors from Ketek GmbH in Munich, Germany; however, these were not available in a suitable time frame for this project, so we worked instead with pnDetector GmbH (also located in Munich). They were able to provide a front-end detector module with six 100 m^2 SDD detectors (two monolithic arrays of three elements each) along with associated preamplifiers; these detectors surpassed the performance we expected to get from the Ketek detectors, however they are housed in a sealed module, which does not offer the ease of repair and expandability we�??d hoped to achieve with the Ketek SDD�??s. Our packaging efforts were quite successful, as we came up with a very compact way to mount the detector and to house the associated electronics, as well as a very effective way to reliably take out the heat (from the electronics as well as the detector�??s Peltier coolers) without risk of condensation and without external airflow or vibration, which could create problems for the target applications. While we were able to design compact processing electronics that fit into the detector assembly, they are still at the prototype stage, and would require a significant redesign to achieve product status. We have not yet tested this detector at a synchrotron facility; we do still plan on working with some close contacts at the nearby Stanford Synchrotron Radiation Laboratory (SSRL) to get some testing with the beam (using existing commercial electronics for readout, as the integrated processor is not ready for use).
Microtomography using a tube source of X-rays, a low-energy-resolution HPGe detector system and an array of detectors
R. Cesareo; D. V. Rao; C. R Appoloni; A. Brunetti
A new microtomographic system has been assembled with a geometrical resolution of about 25�50 mm. This system is employed directly using the bremsstrahlung radiation and filtering the primary radiation with absorbers composed by an element. A reconstruction programme, written in PASCAL is able to give the reconstruction matrix of linear attenuation coefficients, simulates the matrix and the related tomography. Microtomography
Pocked surface neutron detector
McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)
The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.
Induction loop detector systems crosstalk
Bhagat, Victor
traffic control systems are necessary to obtain maximum possible efficiency from our freeway systems. A major component of freeway management systems is the induction loop detector. This research effort evaluated the methods by which crosstalk could...
Transition radiation detectors
Boris Dolgoshein
The use of transition radiation (TR) as a means of identifying high energy particles has now become a subject of intensive experimental investigations and applications. Our intention is first to study the physics of these phenomena and to describe ways of building detectors which can efficiently identify particles.
Enhancement of terahertz coupling efficiency by improved antenna design in GaN/AlGaN high electron mobility transistor detectors
NASA Astrophysics Data System (ADS)
Sun, Yun-Fei; Sun, Jan-Dong; Zhang, Xiao-Yu; Qin, Hua; Zhang, Bao-Shun; Wu, Dong-Min
An optimized micro-gated terahertz detector with novel triple resonant antenna is presented. The novel resonant antenna operates at room temperature and shows more than a 700% increase in photocurrent response compared to the conventional bowtie antenna. In finite-difference-time-domain simulations, we found the performance of the self-mixing GaN/AlGaN high electron mobility transistor detector is mainly dependent on the parameters Lgs (the gap between the gate and the source/drain antenna) and Lw (the gap between the source and drain antenna). With the improved triple resonant antenna, an optimized micrometer-sized AlGaN/GaN high electron mobility transistor detector can achieve a high responsivity of 9.45 � 102 V/W at a frequency of 903 GHz at room temperature.
Monte Carlo simulation of Nal(TI) gamma-spectra in sea water
D. S. Vlachos; C. Tsabaris
In the field of gamma spectroscopy, detection systems such as NaI(Tl), HPGe, CdZnTe, Csl, BaF2, BGO, GaAs are widely known. In a marine environment only the NaI(Tl) and HPGe detectors have been used for in situ monitoring of radioactivity due to their high efficiency and to their capability of detecting in a wide energy range. HPGe detectors have been used
Detection efficiency enhancement of single-photon detector at 1.55-?m by using of single photons lock-in and optimal threshold
NASA Astrophysics Data System (ADS)
Wang, Xiaobo; Zhang, Guofeng; Chen, Ruiyun; Gao, Yan; Xiao, Liantuan; Jia, Suotang
The detection efficiency considerations are often the true determining factor as to whether a sensitive measurement is feasible. We demonstrate a robust method of single photons lock-in to enhance the detection efficiency of InGaAs single-photon avalanche diodes at 1.55-?m wavelength and suppressing background noise. With the optimal threshold for discrimination, the detection efficiency is achieved to 1.87 times bigger than that of the conventional photon counting method.
A Feasibility Study to Determine Cooling Time and Burnup of ATR Fuel Using a Nondestructive Technique and Three Types of Gamma-ray Detectors
Jorge Navarro; Rahmat Aryaeinejad,; David W. Nigg
A Feasibility Study to Determine Cooling Time and Burnup of ATR Fuel Using a Nondestructive Technique1 Rahmat Aryaeinejad, Jorge Navarro, and David W Nigg Idaho National Laboratory Abstract Effective and efficient Advanced Test Reactor (ATR) fuel management require state of the art core modeling tools. These new tools will need isotopic and burnup validation data before they are put into production. To create isotopic, burn up validation libraries and to determine the setup for permanent fuel scanner system a feasibility study was perform. The study consisted in measuring short and long cooling time fuel elements at the ATR canal. Three gamma spectroscopy detectors (HPGe, LaBr3, and HPXe) and two system configurations (above and under water) were used in the feasibility study. The first stage of the study was to investigate which detector and system configuration would be better suited for different scenarios. The second stage of the feasibility study was to create burnup and cooling time calibrations using experimental isotopic data collected and ORIGEN 2.2 burnup data. The results of the study establish that a better spectra resolution is achieve with an above the water configuration and that three detectors can be used in the permanent fuel scanner system for different situations. In addition it was conclude that a number of isotopic ratios and absolute measurements could be used to predict ATR fuel burnup and cooling times. 1This work was supported by the U.S. Depart�ment of Energy (DOE) under Battelle Energy Alliance, LLC Contract No. DE-AC07-05ID14517.
Environmental monitoring using a HPGe-NaI(Tl) compton suppression spectrometer
NASA Astrophysics Data System (ADS)
Chung, Chien; Lee, Cheng-Jong
A multipurpose Compton suppression ?-ray spectrometer is used for environmental monitoring. A high-purity germanium detector is positioned in a large size NaI(Tl) guard detector and coupled to an anticoincidence gating system. Environmental samples of rainwater collected after the Chernobyl accident are monitored with and without anti-Compton operation. The optimum ratio of the peak-to-Compton edge at 662 keV ?-rays is 472:1. The detection limit of 137Cs concentration in a pretreated rain sample is 0.09 Bq for a 20000 s counting period. Characteristics of this spectrometer and features of the ?-ray spectrum collected for fallout monitoring are discussed.
Characterization of naturally occurring radioactive materials in Libyan oil pipe scale using a germanium detector and Monte Carlo simulation
NASA Astrophysics Data System (ADS)
Habib, A. S.; Shutt, A. L.; Regan, P. H.; Matthews, M. C.; Alsulaiti, H.; Bradley, D. A.
Radioactive scale formation in various oil production facilities is acknowledged to pose a potential significant health and environmental issue. The presence of such an issue in Libyan oil fields was recognized as early as 1998. The naturally occurring radioactive materials (NORM) involved in this matter are radium isotopes (226Ra and 228Ra) and their decay products, precipitating into scales formed on the surfaces of production equipment. A field trip to a number of onshore Libyan oil fields has indicated the existence of elevated levels of specific activity in a number of locations in some of the more mature oil fields. In this study, oil scale samples collected from different parts of Libya have been characterized using gamma spectroscopy through use of a well shielded HPGe spectrometer. To avoid potential alpha-bearing dust inhalation and in accord with safe working practices at this University, the samples, contained in plastic bags and existing in different geometries, are not permitted to be opened. MCNP, a Monte Carlo simulation code, is being used to simulate the spectrometer and the scale samples in order to obtain the system absolute efficiency and then to calculate sample specific activities. The samples are assumed to have uniform densities and homogeneously distributed activity. Present results are compared to two extreme situations that were assumed in a previous study: (i) with the entire activity concentrated at a point on the sample surface proximal to the detector, simulating the sample lowest activity, and; (ii) with the entire activity concentrated at a point on the sample surface distal to the detector, simulating the sample highest activity.
Radiation damage of germanium detectors
NASA Technical Reports Server (NTRS)
Pehl, R. H.
Energetic particles can produce interstitial-vacancy pairs in a crystal by knocking the atoms from their normal positions. Detectors are unique among semiconductor devices in depending on very low concentrations of electrically active impurities, and also on efficient transport of holes and electrons over relatively large distances. Because the dense regions of damage produced by energetic particles may result in donors and/or acceptors, and also provide trapping sites for holes and electrons, detectors are very sensitive to radiation damage. In addition to these effects occurring within the detector, radiation may also change the characteristics of the exposed surfaces causing unpredictable effects on the detector leakage current. Radiation-induced surface degradation has rarely, if ever, been observed for germanium detectors. The possibility of minimizing hole trapping in charge collection by the use of a high-purity germanium coaxial detector configured with the p (+) contact on the coaxial periphery is discussed.
High-efficiency single photon detector combined with an ultra-small APD module and a self-training discriminator for high-speed quantum cryptosystems
Seigo Takahashi; Akio Tajima; Akihisa Tomita
A single-photon avalanche detector (SPAD) for high-speed quantum-key generation has successfully been developed. It has the highest photon detection repetition frequency and the lowest dark count rate in the world, as a board-mountable sub-system. The SPAD consists of an ultra-small dual-avalanche photodiode (APD) module and a novel discriminator. The APD module design is consistent with cooling capability and high-frequency characteristics. The new module has a 3 GHz bandwidth enabling 1 GHz gate-pulse repetition. The bandwidth is extended 15-fold relative to the most wideband peltier cooled APD module. The discriminator has a self-training mechanism to compensate charge pulse. Dark count rare of the SPAD is reduced 1/10th relative to the lowest dark count single photon detector. The SPAD allows 3.2-fold multiplying the quantum key generation rate in theoretical estimation.
ERIC Educational Resources Information Center
Harrington-Lueker, Donna
Schools that count on metal detectors to stem the flow of weapons into the schools create a false sense of security. Recommendations include investing in personnel rather than hardware, cultivating the confidence of law-abiding students, and enforcing discipline. Metal detectors can be quite effective at afterschool events. (MLF)
NASA Technical Reports Server (NTRS)
An early warning fire detection sensor developed for NASA's Space Shuttle Orbiter is being evaluated as a possible hazard prevention system for mining operations. The incipient Fire Detector represents an advancement over commercially available smoke detectors in that it senses and signals the presence of a fire condition before the appearance of flame and smoke, offering an extra margin of safety.
Ground Gamma-ray survey by HPGe: Numerical simulations and comparison between field and laboratory measurements
Federico Di Paolo; Wolfango Plastino; Francesco Bella; Mario De Vincenzi; Matthias Laubenstein; Pavel P. Povinec; Antonio Budano; Federico Ruggieri
A comparison between two methodologies for environmental gamma-ray spectrometry were carried out. Laboratory analyses on soil samples were used to test the accuracy of a hand-held portable instrument. Numerical simulations were performed to calibrate detectors and evaluate the actual response of the instrument in the field. Measurements were carried out in a volcanic area, in order to detect the presence
Electronic detectors for electron microscopy.
Faruqi, A R; Henderson, R
Due to the increasing popularity of electron cryo-microscopy (cryoEM) in the structural analysis of large biological molecules and macro-molecular complexes and the need for simple, rapid and efficient readout, there is a persuasive need for improved detectors. Commercial detectors, based on phosphor/fibre optics-coupled CCDs, provide adequate performance for many applications, including electron diffraction. However, due to intrinsic light scattering within the phosphor, spatial resolution is limited. Careful measurements suggest that CCDs have superior performance at lower resolution while all agree that film is still superior at higher resolution. Consequently, new detectors are needed based on more direct detection, thus avoiding the intermediate light conversion step required for CCDs. Two types of direct detectors are discussed in this review. First, there are detectors based on hybrid technology employing a separate pixellated sensor and readout electronics connected with bump bonds-hybrid pixel detectors (HPDs). Second, there are detectors, which are monolithic in that sensor and readout are all in one plane (monolithic active pixel sensor, MAPS). Our discussion is centred on the main parameters of interest to cryoEM users, viz. detective quantum efficiency (DQE), resolution or modulation transfer function (MTF), robustness against radiation damage, speed of readout, signal-to-noise ratio (SNR) and the number of independent pixels available for a given detector. PMID:17913494
The New Position Sensitive Triple Cluster Detector For AGATA
Reiter, P.; Bruyneel, B.; Eberth, J.; Hess, H.; Pascovici, G.; Warr, N.; Wiens, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln (Germany); Thomas, H.-G. [CTT, Montabaur (Germany)
The first triple cluster detector was successfully assembled for the next generation high-resolution gamma-ray spectrometer: the Advanced Gamma Tracking Array AGATA. The core part of the detector consists of three encapsulated, 36-fold segmented, high-purity germanium detectors (HPGe) which are operated in a common cryostat. All 111 energy channels are equipped with cold FETs. They provide best energy resolution of core and segment signals. The observable energy range of the Ge detectors was extended up to 100 MeV by applying a time over threshold technique with the newly developed AGATA preamplifiers. Energy resolution for high energetic {gamma}-rays above 10 MeV is measured to be comparable with values obtained with the standard pulse height technique. Detailed cross-talk investigations were performed in order to improve position dependent pulse shape information. For the Ge detectors and its analog preamplifier circuitry a low cross-talk level was determined which compares well with the expected calculated contributions.
NASA Technical Reports Server (NTRS)
Mcmaster, L. R.; Peterson, S. T.; Hughes, F. M. (inventors)
A meteoroid detector is described which uses, a cold cathode discharge tube with a gas-pressurized cell in space for recording a meteoroid puncture of the cell and for determining the size of the puncture.
NASA Astrophysics Data System (ADS)
Shao, Chun-Lin; Tomita, Kazuhiro; Jimbo, Takashi; Umeno, Masayoshi; Hattori, Shuzo
A new vacuum ultraviolet detector has been fabricated. A sample was made using a crystalline quartz plate on the surface of which a metal electrode was deposited. It has been experimentally established that the sample is sensitive to VUV radiation, and the external quantum efficiency is estimated to be higher than several percent. The new photodetector also has very good stability and should be a practicable new VUV photodetector.
Avalanche semiconductor radiation detectors
Sadygov, Z.Y. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)] [Joint Inst. for Nuclear Research, Dubna (Russian Federation); [Azerbaijan Academy of Sciences, Baku (Azerbaijan). Physics Inst.; Zheleznykh, I.M.; Kirillova, T.A. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research] [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research; Malakhov, N.A.; Jejer, V.N. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)] [Joint Inst. for Nuclear Research, Dubna (Russian Federation)
Operation of novel avalanche semiconductor detector, produced on the basis of heterojunctions Si-SiC and Si-Si{sub x}O{sub y} is described. A uniform avalanche process with gain from 10{sup 3} to 10{sup 5} can be reached depending on the conductivity of SiC and Si{sub x}O{sub y} layers. Two types of avalanche photodetectors designed for applications in wavelength range 500--10,00 nm with quantum efficiency 60 {+-} 10% (650 nm) and 200--700 nm with quantum efficiency 60 {+-} 15% (450 nm) are presented.
Extraordinary improvement in scintillation detectors via post-processing with ASEDRA: solution to a 50-year-old problem
NASA Astrophysics Data System (ADS)
LaVigne, E.; Sjoden, G.; Baciak, J., Jr.; Detwiler, R.
We have developed a ground-breaking algorithm, ASEDRA, to post-process scintillator detector spectra to render photopeaks with high accuracy. The post-processed spectrum is comparable with resolved full energy peaks rendered by high resolution HPGe semiconductor detectors. ASEDRA, or "Advanced Synthetically Enhanced Detector Resolution Algorithm," is currently applied to NaI(Tl) detectors, which are robust, but suffer from poor energy resolution. ASEDRA rapidly post-processes a NaI(Tl) detector spectrum over a few seconds on a standard laptop without prior knowledge of sources or spectrum features. ASEDRA incorporates a novel denoising algorithm based on an adaptive Chi-square methodology called ACHIP, or "Adaptive Chi-quare Processed denoising." Application of ACHIP is necessary to remove stochastic noise, yet preserve fine detail, and can be used as an independent tool for general noise reduction. Following noise removal, ASEDRA sequentially employs an adaptive detector response algorithm to remove the spectrum attributed to specific gammas. Tests conducted using a 2"�2" NaI(Tl) detector, along with a HPGe detector demonstrate the accuracy of ASEDRA; in this paper, we present results using a 152Eu source. Analysis of ASEDRA results show correct identification of at least 15 photopeaks from 152Eu, with relative yield ratios of major lines to better than a factor of two for most cases (referencing the 152Eu 344 keV photopeak), enabling better than a factor of four improvement in resolving peaks compared with unprocessed NaI(Tl). Moreover, denoising and synthetic resolution enhancement algorithms can be adapted to any detector. ACHIP and ASEDRA are covered under a Provisional Patent, Registration Number #60/971,770, 9/12/2007, USPTO.
Performance Comparison of a Large Volume CZT Semiconductor Detector and a LaBr (Ce) Scintillator Detector
Raquel Gonz�lez; Jos� M. P�rez; Oscar Vela; Eduardo de Burgos
The development of portable nuclear instrumentation demands compact high sensitivity detectors operated at room temperature. The sensitivity of these detectors mainly depends on two parameters: absolute efficiency and energy resolution. In order to provide high efficiency, large volumes are needed. For semiconductor detectors able to operate at room temperature, the largest effective volumes with acceptable resolution are achieved with CdZnTe
Performance comparison of a large volume CZT semiconductor detector and a LaBr3(Ce) scintillator detector
Raquel Gonz�lez; Jos� M. P�rez; Oscar Vela; Eduardo de Burgos
The development of portable nuclear instrumentation demands compact high sensitivity detectors operated at room temperature. The sensitivity of these detectors mainly depends on two parameters: absolute efficiency and energy resolution in the range 10-1500 keV. In order to provide high efficiency, large volumes are needed. For semiconductor detectors able to operate at room temperature, the largest effective volumes with acceptable
PHAROS: A pluri-detector, high-resolution, analyser of radiometric properties of soil
NASA Astrophysics Data System (ADS)
Rigollet, C.; de Meijer, R. J.
PHAROS is a new type of core logger, designed to measure activity concentrations of 40K, 238U, 232Th and 137Cs in sediment and rock cores with a spatial resolution of a few centimetres along the core. PHAROS has been developed as a non-destructive alternative to the traditional slicing of cores into sub-samples and their analysis on an HPGe detector. The core is scanned at fixed increments by three BGO scintillation detectors and the spectra analysed by the full spectrum analysis method. The core logger is also equipped with a collimated lead castle and a 137Cs source for transmission measurements. In this paper, we report on the properties of the core logger and its detectors, and on the analysis techniques used for the determination of the radionuclides activity concentrations. Results from initial measurements are presented and discussed.
Cryogenic operation of silicon detectors
P. Collins; I. B. M. Barnett; P. Bartalini; W. Bell; P. Berglund; W. de Boer; S. Buontempo; K. Borer; T. Bowcock; J. Buytaert; L. Casagrande; V. Chabaud; P. Chochula; V. Cindro; C. Da Via; S. Devine; H. Dijkstra; B. Dezillie; Z. Dimcovski; O. Dormond; V. Eremin; A. Esposito; R. Frei; V. Granata; E. Grigoriev; F. Hauler; S. Heising; S. Janos; L. Jungermann; Z. Li; C. Louren�o; M. Mikuz; T. O Niinikoski; V O'Shea; V. G Palmieri; S. Paul; C. Parkes; G. Ruggiero; T. Ruf; S. Saladino; L. Schmitt; K. Smith; I. Stavitski; E. Verbitskaya; F. Vitobello; M. Zavrtanik
This paper reports on measurements at cryogenic temperatures of a silicon microstrip detector irradiated with 24 GeV protons to a fluence of 3.5�1014p\\/cm2 and of a p�n junction diode detector irradiated to a similar fluence. At temperatures below 130 K a recovery of charge collection efficiency and resolution is observed. Under reverse bias conditions this recovery degrades in time towards
Are Teachers Really Poor Talent Detectors? Comments on Pegnato and Birch's (1959) Study of the Effectiveness and Efficiency of Various Identification Techniques.
ERIC Educational Resources Information Center
Gagne, Francoys
Analysis of Pegnato and Birch's data invalidates the observation that teacher nominations should not be relied upon in gifted identification, as analysis shows that effectiveness and efficiency are related to number of subjects singled out as a result of the chosen cutoff value. An alternative is presented: compare correlation coefficients of the�
Large Area and High Efficiency Photon Counting Imaging Detectors with High Time and Spatial Resolution for Night Time Sensing and Astronomy
Michalet, Xavier
relatively low MCP gain (106 ). The background rates are dominated by the thermionic noise of the GaAs National Laboratory, Chicago Il Gary Varner University of Hawaii ABSTRACT Imaging sensors using GaAs been developed. The GaAs photocathodes have peak quantum efficiency of ~30% from 550 nm to 850 nm
The micro void neutron detector
NASA Astrophysics Data System (ADS)
Kocsis, Menyh�rt
The Gas-filled Micro Void Particle Detector is based on gas-filled micro voids placed in an external electric field. This detector presents common features of solid state and gas filled devices as internal amplification, unlimited size and shape, dense, high efficiency parallax reducing structure. The gas filling in the void and/or the wall of the micro void serves as radiation detector. The working principle was tested on syntactic foam composed of glass micro bubbles embedded in an epoxy matrix.
Charged Fusion Product Detector Study
NASA Astrophysics Data System (ADS)
Lopez, Carlos
Plasmas are hot ionized gases which may be manipulated by electromagnetic fields in machines called tokamaks, which are experimental reactors created to harness energy when fusion occurs in said plasma. In order to study instabilities within the tokamak plasma, the trajectories of protons were studied with an array of silicon surface barrier detectors. The collection efficiency of the detectors was analyzed in order to make more accurate calculations, where particular attention was paid to the solid angle of acceptance, or the angular distribution through which particles would enter into the detector. Monte Carlo simulations were coded and implemented in the Python language, where a point on the grid acted as a source which one million data points shot at the plane of the detector. The ratio of the hits versus the misses was calculated for varying positions of the source relative to the plane of the detector. These results were compared to an alpha particle spectroscopy experiment, where a radiation source emitting alpha particles was placed at varying positions relative to the detector. The counting rate of the detector was then observed when it was exposed to the source, and this along with the Monte Carlo results were implemented into an efficiency calculation. DOE Grant # DE-SC0001157.
New detectors for the kaon and hypernuclear experiments with KaoS at MAMI and with PANDA at GSI
P. Achenbach; C. Ayerbe Gayoso; R. B�hm; M. O. Distler; J. Friedrich; K. W. Krygier; H. Merkel; U. M�ller; R. Neuhausen; L. Nungesser; J. Pochodzalla; A. Sanchez Lorente; S. S�nchez Majos; Th. Walcher; J. Gerl; M. Kavatsyuk; I. Kojouhavorv; N. Saito; T. R. Saito; H. Schaffner; T. Bressani; S. Bufalino; A. Feliciello; A. Pantaleo; M. Palomba; G. Raciti; C. Sfienti; M. Agnello; F. Ferro; F. Iazzi; K. Szymanska; P. -E. Tegn�r; B. Cederwall; L. Majling
The KaoS spectrometer at the Mainz Microtron MAMI, Germany, is perceived as the ideal candidate for a dedicated spectrometer in kaon and hypernuclei electroproduction. KaoS will be equipped with new read-out electronics, a completely new focal plane detector package consisting of scintillating fibres, and a new trigger system. First prototypes of the fibre detectors and the associated new front-end electronics are shown in this contribution. The Mainz hypernuclei research program will complement the hypernuclear experiments at the planned FAIR facility at GSI, Germany. At the proposed antiproton storage ring the spectroscopy of double Lambda hypernuclei is one of the four main topics which will be addressed by the PANDA Collaboration. The experiments require the operation of high purity germanium (HPGe) detectors in high magnetic fields (B= 1T) in the presence of a large hadronic background. The performance of high resolution Ge detectors in such an environment has been investigated.
Characteristics of Signals Originating near the Lithium-Diffused N+ Contact of High Purity Germanium P-Type Point Contact Detectors
Aguayo, E. [Pacific Northwest National Laboratory (PNNL); Amman, M. [Lawrence Berkeley National Laboratory (LBNL); Avignone, F. T. [University of South Carolina/ORNL; Barabash, A.S. [Institute of Theoretical & Experimental Physics, Moscow, Russia; Barton, P. J. [Lawrence Berkeley National Laboratory (LBNL); Beene, James R [ORNL; Bertrand Jr, Fred E [ORNL; Boswell, M. [Los Alamos National Laboratory (LANL); Brudanin, V. [Joint Institute for Nuclear Research, Dubna, Russia; Busch, M. [Duke University; Chan, Y-D [Lawrence Berkeley National Laboratory (LBNL); Christofferson, C. D. [South Dakota School of Mines & Technology, Rapid City, SD; Collar, Juan I. [University of Chicago; Combs, D. C. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Cooper, Reynold J [ORNL; Detwiler, J.A. [Lawrence Berkeley National Laboratory (LBNL); Doe, P. J. [University of Washington; Efremenko, Yuri [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Egorov, V. [Joint Institute for Nuclear Research, Dubna, Russia; Ejiri, H. [Osaka University; Elliott, S. R. [Los Alamos National Laboratory (LANL); Esterline, J. [Duke University; Fast, J.E. [Pacific Northwest National Laboratory (PNNL); Fields, N. [University of Chicago; Finnerty, P. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Fraenkle, F. M. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Galindo-Uribarri, Alfredo {nmn} [ORNL; Gehman, V. M. [Los Alamos National Laboratory (LANL); Giovanetti, G. K. [Univ, of North Carolina & Triangle Universities Nucl. Lab - Durham, NC; Green, M. P. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Guiseppe, V.E. [University of South Dakota; Gusey, K. [Joint Institute for Nuclear Research, Dubna, Russia; Hallin, A. L. [University of Alberta, Edmonton, Canada; Hazama, R. [Osaka University; Henning, R. [Univ, of North Carolina & Triangle Universities Nucl. Lab - Durham, NC; Hoppe, E.W. [Pacific Northwest National Laboratory (PNNL); Horton, M. [South Dakota School of Mines & Technology, Rapid City, SD; Howard, S. [South Dakota School of Mines and Technology; Howe, M. A. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Johnson, R. A. [University of Washington, Seattle; Keeter, K.J. [Black Hills State University, Spearfish, SD; Kidd, M. F. [Los Alamos National Laboratory (LANL); Knecht, A. [University of Washington, Seattle; Kochetov, O. [Joint Institute for Nuclear Research, Dubna, Russia; Konovalov, S.I. [Institute of Theoretical & Experimental Physics, Moscow, Russia; Kouzes, R. T. [Pacific Northwest National Laboratory (PNNL); LaFerriere, B. D. [Pacific Northwest National Laboratory (PNNL); Leon, J. [University of Washington, Seattle; Leviner, L. E. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Loach, J.C. [Lawrence Berkeley National Laboratory (LBNL); Looker, Q. [Lawrence Berkeley National Laboratory (LBNL); Luke, P.N. [Lawrence Berkeley National Laboratory (LBNL); MacMullin, S. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Marino, M. G. [University of Washington, Seattle; Martin, R.D. [Lawrence Berkeley National Laboratory (LBNL); Merriman, J. H. [Pacific Northwest National Laboratory (PNNL); Miller, M. L. [University of Washington, Seattle; Mizouni, L. [PPNL/Univ. of South Carolina; Nomachi, M. [Osaka University; Orrell, John L. [Pacific Northwest National Laboratory (PNNL); Overman, N. R. [Pacific Northwest National Laboratory (PNNL); Perumpilly, G. [University of South Dakota; Phillips II, D. G. [University of North Carolina / Triangle Universities Nuclear Lababoratory, Durham; Poon, A.W.P. [Lawrence Berkeley National Laboratory (LBNL); et al.
A study of signals originating near the lithium-diffused n+ contact of p-type point contact (PPC) high purity germanium detectors (HPGe) is presented. The transition region between the active germanium and the fully dead layer of the n+ contact is examined. Energy depositions in this transition region are shown to result in partial charge collection. This provides a mechanism for events with a well defined energy to contribute to the continuum of the energy spectrum at lower energies. A novel technique to quantify the contribution from this source of background is introduced. Experiments that operate germanium detectors with a very low energy threshold may benefit from the methods presented herein.
Determination of ionisation chamber collection efficiency in a swept electron beam by means of thermoluminescent detectors and the "two-voltage" method.
Van Dam, J; Rijnders, A; Ang, K K; Mellaerts, M; Grobet, P
Two methods for determining the collection efficiency of a 0.6 cm3 thimble ionisation chamber exposed to the swept electron beam of a linear accelerator Therac 20 Saturne (CGR MeV) have been compared. In one method the chamber signal has been compared to that of simultaneously exposed thermoluminescent LiF dosemeters (TLD), in the other the "two-voltage" method of Boag, adapted for swept beams, has been used. By variation of the electron energy between 20 and 13 MeV, of the focus-skin-distance (FSD) between 200 and 100 cm and of the monitor rate between 400 monitor units (m.u.) and 100 m.u. per minute, different values could be produced for the peak charge density M. The collection efficiency of the chamber, operating at a standard voltage of 250 V, decreases from 0.99 to 0.84 for a charge density increasing from 0.3 X 10(-4) C/m3 to 7.5 X 10(-4) C/m3, respectively. The maximum deviation observed between the TLD and the "two-voltage" method adopted for similar M is never more than 2% and mostly smaller than 1%. It can be concluded that, under the present experimental conditions, the calculated ionisation chamber collection efficiency is confirmed by the experimental method using TL dosimetry. PMID:3925506
Influence of concentration of magnesium on the dose response and LET-dependence of TL efficiency in LiF:Mg,Cu,P (MCP-N) detectors
P. Bilski; M. Budzanowski; P. Olko; M. P. R. Walig�rski
The highly-sensitive LiF:Mg,Cu,P phosphor, unlike the supralinear LiF:Mg,Ti, exhibits a linear�sublinear dose response after high doses of photon radiation. Also, LiF:Mg,Cu,P shows a much stronger decrease of relative efficiency with increasing ionisation density, especially for heavy charged-particle irradiation. The magnesium dopant most likely governs the trap structure in both phosphors. Dose-response and LET-dependence were therefore studied in LiF:Mg,Cu,P with different
David W. Koppenaal; Charles J. Barinaga; M Bonner B. Denton; Roger P. Sperline; Gary M. Hieftje; Gregory D. Schilling; Francisco J. Andrade; James H. Barnes IV; IV IV
Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the
NSDL National Science Digital Library
This game requires users to match the �??shower shapes�?� and the energies of particles produced in a particle collision. There is also a movie (or animated gif) in the Calorimetry section which allows students to see the workings of the detector. It is part of a collection of games that allows students to explore concepts in particle physics.
Efficiency corrections in determining the (137)Cs inventory of environmental soil samples by using relative measurement method and GEANT4 simulations.
Li, Gang; Liang, Yongfei; Xu, Jiayun; Bai, Lixin
The determination of (137)Cs inventory is widely used to estimate the soil erosion or deposition rate. The generally used method to determine the activity of volumetric samples is the relative measurement method, which employs a calibration standard sample with accurately known activity. This method has great advantages in accuracy and operation only when there is a small difference in elemental composition, sample density and geometry between measuring samples and the calibration standard. Otherwise it needs additional efficiency corrections in the calculating process. The Monte Carlo simulations can handle these correction problems easily with lower financial cost and higher accuracy. This work presents a detailed description to the simulation and calibration procedure for a conventionally used commercial P-type coaxial HPGe detector with cylindrical sample geometry. The effects of sample elemental composition, density and geometry were discussed in detail and calculated in terms of efficiency correction factors. The effect of sample placement was also analyzed, the results indicate that the radioactive nuclides and sample density are not absolutely uniform distributed along the axial direction. At last, a unified binary quadratic functional relationship of efficiency correction factors as a function of sample density and height was obtained by the least square fitting method. This function covers the sample density and height range of 0.8-1.8�g/cm(3) and 3.0-7.25�cm, respectively. The efficiency correction factors calculated by the fitted function are in good agreement with those obtained by the GEANT4 simulations with the determination coefficient value greater than 0.9999. The results obtained in this paper make the above-mentioned relative measurements more accurate and efficient in the routine radioactive analysis of environmental cylindrical soil samples. PMID:25973538
A method to determine 238U activity in environmental soil samples by using 63.3-keV-photopeak-gamma HPGe spectrometer
N. Q. Huy; T. V. Luyen
The paper presents a method of measuring 238U activity in environmental soil samples by a low background HPGe spectrometer at the 63.3keV gamma photopeak. The low 238U activity requires a large size soil sample with a mass of about 100g. The geometrical and self-absorption effects as well as the density dependence of soil samples were then investigated. A procedure of
Development of cryogenic detectors for radioactivity metrology
E Leblanc; P Cassette; J Bouchard; J Plagnard
Low temperature detectors are expected to improve radioactivity measurements as they offer two major advantages compared to classical semiconductor detectors: excellent energy resolution (10eV for 6keV X-rays) and 100% detection efficiency for low energy X-rays (i.e. 1�10keV). The main difficulties encountered in the development of such detectors are their high sensitivity to electromagnetic noise and acoustic vibrations. These difficulties are
NASA Technical Reports Server (NTRS)
Scientific Instruments, Inc. has now developed a second generation, commercially available instrument to detect flames in hazardous environments, typically refineries, chemical plants and offshore drilling platforms. The Model 74000 detector incorporates a sensing circuit that detects UV radiation in a 100 degree conical field of view extending as far as 250 feet from the instrument. It operates in a bandwidth that makes it virtually 'blind' to solar radiation while affording extremely high sensitivity to ultraviolet flame detection. A 'windowing' technique accurately discriminates between background UV radiation and ultraviolet emitted from an actual flame, hence the user is assured of no false alarms. Model 7410CP is a combination controller and annunciator panel designed to monitor and control as many as 24 flame detectors. *Model 74000 is no longer being manufactured.
Characterization of Large Liquid Scintillation Detectors
Pozzi, S.A.
This report presents the results of the characterization of 11 large liquid scintillators. The neutron energy threshold and maximum detection efficiency were determined as a function of voltage and constant fraction discriminator threshold. Fits to the response of each detector were found. The results can be used to select the experimental settings in the operation of the detectors to ensure consistent response and repeatability.
Gallium arsenide detectors for minimum ionizing particles
S. B. Beaumont; R. Bertin; C. N. Booth; C. Buttar; C. Capiluppi; L. Carraresi; F. Cindolo; M. Colocci; F. H. Combley; S. D. Auria; C. del Papa; M. Dogru; M. Edwards; F. Fiori; F. Foster; A. Francescato; R. Gray; G. Hill; Y. Hou; P. Houston; G. Hughes; B. K. Jones; J. G. Lynch; B. Lisowsky; J. Matheson; F. Nava; M. Nuti; V. O'Shea; P. G. Pelfer; C. Raine; J. Santana; I. J. Saunders; P. H. Seller; K. Shankar; P. H. Sharp; I. O. Skillicorn; T. Sloan; K. M. Smith; N. Tartoni; I. Ten Have; R. M. Turnbull; U. Vanni; A. Vinattieri; A. Zichichi
Progress on the development of GaAs solid state detectors is presented. 80% charge collection efficiency has been achieved, and double sided detectors with metal rectifying contacts have been tested. Measurements of capacitance and tests with SEM are giving more information on the behaviour of these devices.
Detector requirements for space infrared astronomy
NASA Technical Reports Server (NTRS)
Wright, E. L.
Requirements for background-limited (BLIP) detectors are discussed in terms of number of photons falling on each pixel, dark current, high detective quantum efficiencies, large numbers of pixels, and array size.
Flexible composite radiation detector
Cooke, D. Wayne (Santa Fe, NM); Bennett, Bryan L. (Los Alamos, NM); Muenchausen, Ross E. (Los Alamos, NM); Wrobleski, Debra A. (Los Alamos, NM); Orler, Edward B. (Los Alamos, NM)
A flexible composite scintillator was prepared by mixing fast, bright, dense rare-earth doped powdered oxyorthosilicate (such as LSO:Ce, LSO:Sm, and GSO:Ce) scintillator with a polymer binder. The binder is transparent to the scintillator emission. The composite is seamless and can be made large and in a wide variety of shapes. Importantly, the composite can be tailored to emit light in a spectral region that matches the optimum response of photomultipliers (about 400 nanometers) or photodiodes (about 600 nanometers), which maximizes the overall detector efficiency.
Metal-semiconductor, composite radiation detectors
NASA Astrophysics Data System (ADS)
Orvis, W. J.; Yee, J. H.; Fuess, D.
In 1989, two researchers published a design for an increased efficiency x-ray detector. The design increased the efficiency of a semiconductor detector by interspersing layers of high-z metal within it. Semiconductors such as silicon make good, high-resolution radiation detectors, but they have low efficiency because they are low-z materials (z = 14). High-z metals, on the other hand, are good absorbers of high-energy photons. By interspersing high-z metal layers with semiconductor layers, the researchers combined the high absorption efficiency of the high-z metals with the good detection capabilities of a semiconductor. This project is an attempt to use the same design to produce a high-efficiency, room temperature gamma ray detector. By their nature, gamma rays require thicker metal layers to efficiently absorb them. These thicker layers change the behavior of the detector by reducing the resolution, compared to a solid state detector, and shifting the photopeak by a predictable amount. During the last year, the authors have procured and tested a commercial device with operating characteristics similar to those of a single layer of the composite device. They have modeled the radiation transport in a multi-layered device, to verify the initial calculations of layer thickness and composition. They have modeled the electrostatic field in different device designs to locate and remove high-field regions that can cause device breakdown. They have fabricated 14 single layer prototypes.
Coincidence-summing correction equations in gamma-ray spectrometry with p-type HPGedetectors
E. Tomarchio; S. Rizzo
Equations to compute ??? and ??XK coincidence-summing corrections in gamma-ray spectrometry with p-type HPGe detectors are reported. For point sources only full-energy-peak and total efficiencies are needed.
Johnson noise limited operation of photovoltaic InSb detectors
D. N. B. Hall; R. S. Aikens; R. Joyce; T. W. McCurnin
Photovoltaic indium antimonide detectors have been operated at temperatures less than 77 K with sufficiently low background radiation levels that Johnson noise limited performance is realized. Under such conditions the noise equivalent power (NEP) is completely determined by the detector operating temperature, resistance, and quantum efficiency. Optimization of these parameters in the manufacture of commercially available detectors has led to
Interdefect charge exchange in silicon particle detectors at cryogenic temperatures
Barry MacEvoy; Attilio Santocchia; G. Hall; F. Moscatelli; D. Passeri; G. M. Bilei
Silicon particle detectors in the next generation of experiments at the CERN Large Hadron Collider will be exposed to a very challenging radiation environment. The principal obstacle to long-term operation arises from changes in detector doping concentration (Neff), which lead to an increase in the bias required to deplete the detector and hence achieve efficient charge collection. We have previously
Microradiography with Semiconductor Pixel Detectors
Jakubek, Jan; Cejnarova, Andrea; Dammer, Jiri; Holy, Tomas; Platkevic, Michal; Pospisil, Stanislav; Vavrik, Daniel; Vykydal, Zdenek [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, CZ 12800 Prague 2 (Czech Republic)
High resolution radiography (with X-rays, neutrons, heavy charged particles, ...) often exploited also in tomographic mode to provide 3D images stands as a powerful imaging technique for instant and nondestructive visualization of fine internal structure of objects. Novel types of semiconductor single particle counting pixel detectors offer many advantages for radiation imaging: high detection efficiency, energy discrimination or direct energy measurement, noiseless digital integration (counting), high frame rate and virtually unlimited dynamic range. This article shows the application and potential of pixel detectors (such as Medipix2 or TimePix) in different fields of radiation imaging.
Development of innovative silicon radiation detectors
Balbuena, JuanPablo
Silicon radiation detectors fabricated at the IMB-CNM (CSIC) Clean Room facilities using the most innovative techniques in detector technology are presented in this thesis. TCAD simulation comprises an important part in this work as becomes an essential tool to achieve exhaustive performance information of modelled detectors prior their fabrication and subsequent electrical characterization. Radiation tolerance is also investigated in this work using TCAD simulations through the potential and electric field distributions, leakage current and capacitance characteristics and the response of the detectors to the pass of different particles for charge collection efficiencies. Silicon detectors investigated in this thesis were developed for specific projects but also for applications in experiments which can benefit from their improved characteristics, as described in Chapter 1. Double-sided double type columns 3D (3D-DDTC) detectors have been developed under the NEWATLASPIXEL project in the framework of the CERN ...
G. A. Morton
Nuclear radiation detectors are required in all the major fields of nuclear science and technology. They fall into two principal categories, single element detectors and imaging detectors. Single element detectors can be classified into four types, based upon their physical mode of operation. These are 1) Scintillation counters, 2) Gas ionization detectors, a) Ionization chambers, b) Proportional counters, c) Geiger-Mueller
Thallium bromide radiation detectors
K. S. Shah; J. C. Lund; F. Olschner; L. Moy; M. R. Squillante
Radiation detectors have been fabricated from crystals of the semiconductor material thallium bromide (TlBr) and the performance of these detectors as room temperature photon spectrometers has been measured. These detectors exhibit improved energy resolution over previously reported TlBr detectors. These results indicate that TlBr is a very promising radiation detector material.
Integrating Pixel Array Detector Development
NASA Astrophysics Data System (ADS)
Gruner, Sol
X-ray experiments are very frequently detector limited at storage ring synchrotron radiation sources, and will be even more so at future x-ray free electron laser and energy recovery linac sources. Limitations most frequently arise from the inability of detectors to efficiently collect and process data at the rates at which the data can be generated. Two bump-bonded silicon pixel array detectors (PADs) are being developed at Cornell University that will greatly enhance data collection capabilities. In these PADs x-rays are converted to electrical signals in a pixelated layer of high resistivity silicon, each pixel of which is connected by a metal solder ``bump'' to a corresponding pixel in a CMOS silicon integrated circuit. Each CMOS pixel contains its own data handling and processing electronics. Since all pixels operate in parallel, the PAD is capable of handling extremely high data throughput. The PAD pixels feature integrating analog front-end electronics which allow extremely high instantaneous count-rates, yet sufficiently high signal-to-noise to be able to detect single x-ray photons. The first PAD is designed for coherent x-ray imaging experiments at the Linac Coherent Light Source (LCLS) at SLAC. This detector frames continuously at the LCLS rate of 120 Hz, where the data for each frame can arrive in femtoseconds. The second detector, a result of a collaboration with the Area Detector Systems Corporation, is designed for high throughput protein crystallography experiments. Both detectors are described, and test data is provided. The capabilities of the detectors suggest a variety of new applications, some of which will be discussed.
Potter, B.M.
An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.
GaN-based PIN alpha particle detectors
Guo Wang; Kai Fu; Chang-sheng Yao; Dan Su; Guo-guang Zhang; Jin-yan Wang; Min Lu
GaN-based PIN alpha particle detectors are studied in this article. The electrical properties of detectors have been investigated, such as current�voltage (I�V) and capacitance�voltage (C�V). The reverse current of all detectors is in nA range applied at 30V, which is suitable for detector operation. The charge collection efficiency (CCE) is measured to be approximately 80% but the energy resolution is
Efficiency corrections in low-energy gamma spectrometry
NASA Astrophysics Data System (ADS)
Isakar, K.; Realo, K.; Kiisk, M.; Realo, E.
In HPGe gamma spectrometric analysis of 210Pb in aerosol filter samples, the activity concentrations were corrected for self-attenuation and sample heights. Corrections were evaluated using the Monte Carlo simulation toolkit Geant4 and the Gespecor software. Calculations were made for 46.5 keV gamma line of 210Pb in Petryanoff (FPP) and fiberglass aerosol filters of varying heights. The IAEA RGU-1 reference material of different heights in a similar beaker served as a standard source. As a result, the approximations were found to calculate corrected efficiencies for samples with different heights. The method was applied for the study of 210Pb content in air in Estonia.
Southwest Research Institute intensified detector development capability
NASA Astrophysics Data System (ADS)
Wilkinson, Erik; Vincent, Michael; Kofoed, Christopher; Andrews, John; Brownsberger, Judith; Siegmund, Oswald
Imaging detectors for wavelengths between 10 nm and 105 nm generally rely on microchannel plates (MCPs) to provide photon detection (via the photo-electric effect) and charge amplification. This is because silicon-based detectors (CCD or APS) have near zero quantum detection efficiency (QDE) over this wavelength regime. Combining a MCP based intensifier tube with a silicon detector creates a detector system that can be tuned to the wavelength regime of interest for a variety of applications. Intensified detectors are used in a variety of scientific (e.g. Solar Physics) and commercial applications (spectroscopic test instrumentation, night vision goggles, low intensity cameras, etc.). Building an intensified detector requires the mastery of a variety of technologies involved in integrating and testing of these detector systems. We report on an internally funded development program within the Southwest Research Institute to architect, design, integrate, and test intensified imaging detectors for space-based applications. Through a rigorous hardware program the effort is developing and maturing the technologies necessary to build and test a large format (2k � 2k) UV intensified CCD detector. The intensified CCD is designed around a commercially available CCD that is optically coupled to a UV Intensifier Tube from Sensor Sciences, LLC. The program aims to demonstrate, through hardware validation, the ability to architect and execute the integration steps necessary to produce detector systems suitable for space-based applications.
Luiz Alexandre Schuch; Daniel Jean Roger Nordemann
Detectors of nuclear radiation, such as gaseous detectors, scintillators, and semiconductors, are presented through their general properties and with their operating systems. The semiconductor detectors are studied with more details.
SU-E-I-62: Assessing Radiation Dose Reduction and CT Image Optimization Through the Measurement and Analysis of the Detector Quantum Efficiency (DQE) of CT Images Using Different Beam Hardening Filters
Collier, J; Aldoohan, S; Gill, K
Purpose: Reducing patient dose while maintaining (or even improving) image quality is one of the foremost goals in CT imaging. To this end, we consider the feasibility of optimizing CT scan protocols in conjunction with the application of different beam-hardening filtrations and assess this augmentation through noise-power spectrum (NPS) and detector quantum efficiency (DQE) analysis. Methods: American College of Radiology (ACR) and Catphan phantoms (The Phantom Laboratory) were scanned with a 64 slice CT scanner when additional filtration of thickness and composition (e.g., copper, nickel, tantalum, titanium, and tungsten) had been applied. A MATLAB-based code was employed to calculate the image of noise NPS. The Catphan Image Owl software suite was then used to compute the modulated transfer function (MTF) responses of the scanner. The DQE for each additional filter, including the inherent filtration, was then computed from these values. Finally, CT dose index (CTDIvol) values were obtained for each applied filtration through the use of a 100 mm pencil ionization chamber and CT dose phantom. Results: NPS, MTF, and DQE values were computed for each applied filtration and compared to the reference case of inherent beam-hardening filtration only. Results showed that the NPS values were reduced between 5 and 12% compared to inherent filtration case. Additionally, CTDIvol values were reduced between 15 and 27% depending on the composition of filtration applied. However, no noticeable changes in image contrast-to-noise ratios were noted. Conclusion: The reduction in the quanta noise section of the NPS profile found in this phantom-based study is encouraging. The reduction in both noise and dose through the application of beam-hardening filters is reflected in our phantom image quality. However, further investigation is needed to ascertain the applicability of this approach to reducing patient dose while maintaining diagnostically acceptable image qualities in a clinical setting.
Neutron-chamber detectors and applications
NASA Astrophysics Data System (ADS)
Fehlau, Paul E.; Atwater, Henry F.; Coop, Kenneth L.
Detector applications in nuclear safeguards and waste management have included measuring neutrons from fission and (?, n) reactions with well-moderated neutron proportional counters, often embedded in a slab of polyethylene. Other less-moderated geometries are useful for detecting both bare and moderated fission-source neutrons with good efficiency. The neutron chamber is an undermoderated detector design comprising a large, hollow, polyethylene-walled chamber containing one or more proportional counters. Neutron-chamber detectors are relatively inexpensive, can have large apertures, usually through a thin chamber wall, and offer very good detection efficiency per dollar. For 10% of the cost, a neutron-chamber detector may give one-half the total detection efficiency of a slab detector for detecting neutrons from a distant, bare source. A nuclear-safeguards pedestrian monitor detects concealed plutonium using two such chamber detectors to form a walk-through portal. Neutron-chamber detectors have also been used for monitoring vehicles and for assaying large crates of transuranic waste. Our Monte Carlo calculations for a new application (monitoring low-density waste for concealed plutonium) illustrate the advantages of the hollow-chamber design for detecting moderated fission sources.
Design and Implementation of a Low Cost VLF Metal Detector with Metal-Type Discrimination Capabilities
Mohammad S. Sharawi; M. I. Sharawi
Land mine detectors, security metal doors that we all go through in buildings and airports, as well as metal mining detectors are just examples of metal detector use in our daily lives. In this paper we present a cost efficient, low complexity very low frequency (VLF) handheld reconfigurable metal detector (MD) design and implementation that has the capability of discriminating
High-spatial resolution and high-spectral resolution detector for use in the measurement of solar flare hard X-rays
NASA Technical Reports Server (NTRS)
Desai, U. D.; Orwig, Larry E.
In the areas of high spatial resolution, the evaluation of a hard X-ray detector with 65 micron spatial resolution for operation in the energy range from 30 to 400 keV is proposed. The basic detector is a thick large-area scintillator faceplate, composed of a matrix of high-density scintillating glass fibers, attached to a proximity type image intensifier tube with a resistive-anode digital readout system. Such a detector, combined with a coded-aperture mask, would be ideal for use as a modest-sized hard X-ray imaging instrument up to X-ray energies as high as several hundred keV. As an integral part of this study it was also proposed that several techniques be critically evaluated for X-ray image coding which could be used with this detector. In the area of high spectral resolution, it is proposed to evaluate two different types of detectors for use as X-ray spectrometers for solar flares: planar silicon detectors and high-purity germanium detectors (HPGe). Instruments utilizing these high-spatial-resolution detectors for hard X-ray imaging measurements from 30 to 400 keV and high-spectral-resolution detectors for measurements over a similar energy range would be ideally suited for making crucial solar flare observations during the upcoming maximum in the solar cycle.
Detector simulation needs for detector designers
Hanson, G.G.
Computer simulation of the components of SSC detectors and of the complete detectors will be very important for the designs of the detectors. The ratio of events from interesting physics to events from background processes is very low, so detailed understanding of detector response to the backgrounds is needed. Any large detector for the SSC will be very complex and expensive and every effort must be made to design detectors which will have excellent performance and will not have to undergo major rebuilding. Some areas in which computer simulation is particularly needed are pattern recognition in tracking detectors and development of shower simulation code which can be trusted as an aid in the design and optimization of calorimeters, including their electron identification performance. Existing codes require too much computer time to be practical and need to be compared with test beam data at energies of several hundred GeV. Computer simulation of the processing of the data, including electronics response to the signals from the detector components, processing of the data by microprocessors on the detector, the trigger, and data acquisition will be required. In this report we discuss the detector simulation needs for detector designers.
S. Fukuda; Y. Fukuda; T. Hayakawa; E. Ichihara; M. Ishitsuka; Y. Itow; T. Kajita; J. Kameda; K. Kaneyuki; S. Kasuga; K. Kobayashi; Y. Kobayashi; Y. Koshio; M. Miura; S. Moriyama; M. Nakahata; S. Nakayama; T. Namba; Y. Obayashi; A. Okada; M. Oketa; K. Okumura; T. Oyabu; N. Sakurai; M. Shiozawa; Y. Suzuki; Y. Takeuchi; T. Toshito; Y. Totsuka; S. Yamada; S. Desai; M. Earl; J. T. Hong; E. Kearns; M. Masuzawa; M. D. Messier; J. L. Stone; L. R. Sulak; C. W. Walter; W. Wang; K. Scholberg; T. Barszczak; D. Casper; D. W. Liu; W. Gajewski; P. G. Halverson; J. Hsu; W. R. Kropp; S. Mine; L. R. Price; F. Reines; M. Smy; H. W. Sobel; M. R. Vagins; K. S. Ganezer; W. E. Keig; R. W. Ellsworth; S. Tasaka; J. W. Flanagan; A. Kibayashi; J. G. Learned; S. Matsuno; V. J. Stenger; Y. Hayato; T. Ishii; A. Ichikawa; J. Kanzaki; T. Kobayashi; T. Maruyama; K. Nakamura; Y. Oyama; A. Sakai; M. Sakuda; O. Sasaki; S. Echigo; T. Iwashita; M. Kohama; A. Suzuki; M. Hasegawa; T. Inagaki; I. Kato; H. Maesaka; T. Nakaya; K. Nishikawa; S. Yamamoto; T. J. Haines; B. K. Kim; R. Sanford; R. Svoboda; E. Blaufuss; M. L. Chen; Z. Conner; J. A. Goodman; E. Guillian; G. W. Sullivan; D. Turcan; A. Habig; M. Ackerman; F. Goebel; J. Hill; C. K. Jung; T. Kato; D. Kerr; M. Malek; K. Martens; C. Mauger; C. McGrew; E. Sharkey; B. Viren; C. Yanagisawa; W. Doki; S. Inaba; K. Ito; M. Kirisawa; M. Kitaguchi; C. Mitsuda; K. Miyano; C. Saji; M. Takahata; M. Takahashi; K. Higuchi; Y. Kajiyama; A. Kusano; Y. Nagashima; K. Nitta; M. Takita; T. Yamaguchi; M. Yoshida; H. I. Kim; S. B. Kim; J. Yoo; H. Okazawa; M. Etoh; K. Fujita; Y. Gando; A. Hasegawa; T. Hasegawa; S. Hatakeyama; K. Inoue; K. Ishihara; T. Iwamoto; M. Koga; I. Nishiyama; H. Ogawa; J. Shirai; T. Takayama; F. Tsushima; M. Koshiba; Y. Ichikawa; T. Hashimoto; Y. Hatakeyama; M. Koike; T. Horiuchi; M. Nemoto; K. Nishijima; H. Takeda; H. Fujiyasu; T. Futagami; H. Ishino; Y. Kanaya; M. Morii; H. Nishihama; H. Nishimura; T. Suzuki; Y. Watanabe; D. Kielczewska; U. Golebiewska; H. G. Berns; S. B. Boyd; R. A. Doyle; J. S. George; A. L. Stachyra; L. L. Wai; R. J. Wilkes; K. K. Young; H. Kobayashi
Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons. During the period April, 1996 to July, 2001, Super-Kamiokande I collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency. These data provided crucial information for our current understanding of neutrino oscillations, as well as setting
High resolution gamma ray spectroscopy with CdTe detector systems
M. Richter; P. Siffert
Energy resolution and photopeak efficiency of the nowadays CdTe detector material can be improved using several detector shapes or electronic signal processing. Current results obtained in our laboratory with different detector geometries and pulse discrimination methods are presented and compared. Finally, we report on a new charge loss compensation method which improves both energy resolution and photopeak efficiency.
Neutron spectrometer for ITER using silicon detectors
Conroy, Sean W.; Weiszflog, Matthias; Andersson-Sunden, Erik; Ericsson, Goran; Gatu-Johnson, Maria; Hellesen, Carl; Ronchi, Emanuel; Sjostrand, Henrik [Department of Physics and Astronomy, Uppsala University, EURATOM-VR, Uppsala 75120 (Sweden)
High resolution neutron spectrometers provide information about plasma parameters at existing fusion experiments. Such a system may also be employed at ITER. Proton recoil telescopes have classically been used to detect neutrons with good energy resolution but poor efficiency. Using annular silicon detectors, it is possible to greatly increase the solid angle coverage and hence improve efficiency. Based on a simulation (MCNPX) study, the scaling of energy resolution, efficiency, and time to determine an ion temperature to 10% accuracy on foil thickness and detector location is shown. The latter quantity is used to determine the optimum foil thickness and detector geometry for specific plasma temperatures. For a 20 keV deuterium-tritium (DT) plasma, 5.3% resolution with efficiency of 2.9x10{sup -4} n cm{sup 2} is attainable using the available detectors. This gives a temperature measurement with 10% accuracy in 1.1 ms for a neutron flux of 2x10{sup 9} n cm{sup -2}. Multiple detectors can be used to further increase the efficiency if needed. A system of this kind could be tested in a future DT campaign at, for example, JET.
Pavel Rehak
A rapid progress of past 20 years in silicon radiation detectors is reviewed. The availability of silicon as almost ideal semiconductor material is one of the main reasons for this progress. The well-defined properties of the silicon-silicon dioxide interface allowed the development of detector structures beyond the structure of a classical diode detector, which was practically the only silicon detector
The LUX prototype detector: Heat exchanger development
NASA Astrophysics Data System (ADS)
Akerib, D. S.; Bai, X.; Bedikian, S.; Bernstein, A.; Bolozdynya, A.; Bradley, A.; Cahn, S. B.; Carr, D.; Chapman, J. J.; Clark, K.; Classen, T.; Curioni, A.; Dahl, C. E.; Dazeley, S.; de Viveiros, L.; Dragowsky, M.; Druszkiewicz, E.; Fiorucci, S.; Gaitskell, R. J.; Hall, C.; Faham, C.; Holbrook, B.; Kastens, L.; Kazkaz, K.; Kwong, J.; Lander, R.; Leonard, D.; Malling, D.; Mannino, R.; McKinsey, D. N.; Mei, D.; Mock, J.; Morii, M.; Nikkel, J. A.; Phelps, P.; Shutt, T.; Skulski, W.; Sorensen, P.; Spaans, J.; Steigler, T.; Svoboda, R.; Sweany, M.; Thomson, J.; Tripathi, M.; Walsh, N.; Webb, R.; White, J.; Wolfs, F. L. H.; Woods, M.; Zhang, C.
The LUX (large underground xenon) detector is a two-phase xenon time projection chamber (TPC) designed to search for WIMP-nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large (>1 ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper, we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1 m to be achieved in approximately 2 days and sustained for the duration of the testing period.
Calibration of the LUX Dark Matter Detector
NASA Astrophysics Data System (ADS)
Kastens, Louis
Calibration strategies for LUX (Large Underground Xenon), a liquid xenon time projection chamber designed to directly detect dark matter, will be explored. The introduction of external gamma and neutron sources into a water tank containing the detector will be discussed. Large liquid noble detectors achieve very low backgrounds through self-shielding of the fiducial volume, however this same shielding inhibits the use of external gamma ray sources to calibrate the fiducial volume detector. To mitigate this effect, research on novel calibration strategies using radioactive ^83mKr and ^3He doped into the detector to efficiently calibrate the fiducial volume of these detectors will be reported upon. LUX will be deploying to Davis Cavern at SUSEL (Sanford Underground Science and Engineering Laboratory), future site of DUSEL (Deep Underground Science and Engineering Laboratory), in the first half of 2010. )
The CLEO III silicon vertex detector
R. Kass; M. S. Alam; J. P. Alexander; A. Anastassov; K. Arndt; A. Bean; F. Blanc; G. Boyd; G. W. Brandenburg; J. W. Cherwinka; J. E. Duboscq; E. Eckhart; A. Ershov; J. Fast; A. D. Foland; P. I. Hopman; K. K. Gan; Y. Gao; H. P. Kagan; S. Kane; L. Kazkaz; D. Kim; J. Lee; A. J. Magerkurth; D. Miller; J. Miyamoto; M. Neustadt; J. Oliver; V. Pavlunin; C. Rush; T. Selby; H. Severini; I. Shipsey; P. Skubic; T. Smith; P. Sterner; S. Timm; E. von Toerne; D. Tournear; C. W. Ward; Q. Zhang; X. Zhao; M. M. Zoeller
The design and operation of the CLEO III silicon vertex detector is described in this report. This detector consists of four layers of double-sided silicon wafers covering 93% of the solid angle. After initially meeting its signal-to-noise and spatial resolution design goals, the r?? side efficiency of layers 1 and 2 decreased dramatically due to radiation-induced sensor effects.
The CLEO III silicon vertex detector
NASA Astrophysics Data System (ADS)
Kass, R.; Alam, M. S.; Alexander, J. P.; Anastassov, A.; Arndt, K.; Bean, A.; Blanc, F.; Boyd, G.; Brandenburg, G. W.; Cherwinka, J. W.; Duboscq, J. E.; Eckhart, E.; Ershov, A.; Fast, J.; Foland, A. D.; Hopman, P. I.; Gan, K. K.; Gao, Y.; Kagan, H. P.; Kane, S.; Kazkaz, L.; Kim, D.; Lee, J.; Magerkurth, A. J.; Miller, D.; Miyamoto, J.; Neustadt, M.; Oliver, J.; Pavlunin, V.; Rush, C.; Selby, T.; Severini, H.; Shipsey, I.; Skubic, P.; Smith, T.; Sterner, P.; Timm, S.; von Toerne, E.; Tournear, D.; Ward, C. W.; Zhang, Q.; Zhao, X.; Zoeller, M. M.
The design and operation of the CLEO III silicon vertex detector is described in this report. This detector consists of four layers of double-sided silicon wafers covering 93% of the solid angle. After initially meeting its signal-to-noise and spatial resolution design goals, the r- ? side efficiency of layers 1 and 2 decreased dramatically due to radiation-induced sensor effects.
Carbon nanotube based spectrum infrared detectors
Ning Xi; Harold Szu; James Buss; Ingham Mack
Carbon nanotubes (CNT) have a potential to be efficient infrared (IR) detection materials due to their unique electronic properties. The ballistic electronic transport property makes the noise equivalent temperature difference smaller compared to other semi-conducting materials. By overlaying CNT-based mid-IR (3-5mu) detectors on a long-wave IR (8-15mu) focal plane array, the mid-IR detector causes no filters loss. In order to
Thallium Bromide Nuclear Radiation Detector Development
Alexei V. Churilov; Guido Ciampi; Hadong Kim; Leonard J. Cirignano; William M. Higgins; Fred Olschner; Kanai S. Shah
Thallium bromide (TlBr) is a dense, high-Z, wide bandgap semiconductor that has potential as an efficient, compact, room temperature nuclear radiation detector. In this paper we report on our recent progress in TlBr nuclear detector development. In particular, improvements in material purification have led to an order of magnitude increase in the mobility-lifetime product of electrons, (mutau)e, to as high
A panoramic photon-counting detector system
NASA Astrophysics Data System (ADS)
Durand, Daniel; Hardy, Eduardo; Couture, Jean
The characteristics and implementation of the Laval Image Photon-Counting System (LIPS) are described. LIPS is a flexible, compact, and transportable two-dimensional detector system which is currently in use in the spectroscopic mode on the 1.6 m telescope at the Mont Megantic Observatory. The detector is described, including the quantum efficiency, resolution, linearity, noise characteristics, and distortions. The data acquisition and display module is considered, including the computer, image display unit, Direct Memory Access Board which controls the detector, and control and data-acquisition program. Spectroscopy using LIPS is briefly addressed. The present assessment of the system and its future use are discussed.
Operational experience with the CMS pixel detector
NASA Astrophysics Data System (ADS)
Karancsi, J.
In the first LHC running period the CMS pixel detector had to face various operational challenges and had to adapt to the rapidly changing beam conditions. In order to maximize the physics potential and the quality of the data, online and offline calibrations were performed on a regular basis. The detector performed excellently with an average hit efficiency above 99% for all layers and disks. In this contribution the operational challenges of the silicon pixel detector in the first LHC run and the current long shutdown are summarized and the expectations for 2015 are discussed.
Calculation of detection efficiency for beryllium-8
Wolfe, G.W.
A method has been developed, using Monte-Carlo techniques, to calculate the detection efficiency for /sup 8/Be particles from either solid or gaseous targets, using single detectors, binocular detectors, or position sensitive detectors. As a demonstration of the method, the /sup 24/Mg(..cap alpha..,/sup 8/Be)/sup 20/Ne reaction was attempted at an alpha energy of 65 MeV. The efficiency calculation above is shown to be in general agreement with other similar work.
Operation and performance of new NIR detectors from SELEX
NASA Astrophysics Data System (ADS)
Atkinson, D.; Bezawada, N.; Hipwood, L. G.; Shorrocks, N.; Milne, H.
The European Space Agency (ESA) has funded SELEX Galileo, Southampton, UK to develop large format near infrared (NIR) detectors for its future space and ground based programmes. The UKATC has worked in collaboration with SELEX Galileo to test and characterise the new detectors produced during phase-1 of the development. In order to demonstrate the detector material performance, the HgCdTe (MCT) detector diodes (grown on GaAs substrate through MOVPE process in small 320�256, 24?m pixel format) are hybridised to the existing SELEX Galileo SWALLOW CMOS readout chip. The substrate removed and MCT thinned detector arrays were then tested and evaluated at the UKATC following screening tests at SELEX. This paper briefly describes the test setup, the operational aspects of the readout multiplexer and presents the performance parameters of the detector arrays including: conversion gain, detector dark current, read noise, linearity, quantum efficiency and persistence for various detector temperatures between 80K and 140K.
Test vehicle detector characterization system for the Boeing YAL-1 airborne laser
Steininger-Holmes, Jason Thomas
The test vehicle detector characterization system provides a convenient and efficient tool for rapidly evaluating the optical sensitivity of the GAP6012, GAP100, GAP300, and GAP1000 indium gallium arsenide detectors used ...
Development of {gamma}-ray detectors for {sup 16}O(p,p'{gamma}) experiment
Mori, T.; Izumi, T.; Ou, I.; Yano, T.; Sakuda, M.; Tamii, A.; Suzuki, T.; Yosoi, M. [Department of physiscs, Okayama University, Okaymaa 700-8530 (Japan); Research Center for Nuclear Physics (RCNP), Ibaraki, Osaka 567-0047 (Japan)
The {gamma} ray production in neutral-current (NC) neutrino-oxygen interaction is very important to the detection of neutrinos from supernova explosion in a neutrino experiment, since those {gamma} rays can become extra signals or unexpected background in the energy region from 5 MeV to 30 MeV. We propose the experiment to measure {gamma} rays in {sup 16}O(p,p') reaction at Research Center for Nuclear Physics (RCNP, Osaka) to provide good information on the {gamma}-ray emission spectra in neutrino-oxygen reactions. We present the design of {gamma}-ray detectors (NaI, CsI, HPGe), which will be used in proposed experiment.
18F half-life measurement using a high-purity germanium detector.
Han, Jubong; Lee, K B; Park, T S; Lee, J M; Oh, P J; Lee, S H; Kang, Y S; Ahn, J K
The half-life of (18)F has been measured using HPGe detectors with a (137)Cs reference source. The counting ratio of 511 keV ?-rays from (18)F to 622 keV ?-rays from (137)Cs was fitted for the half-life with a weighted least-square method. Uncertainties due to the systematic effects arising from the measurement of a high activity (18)F source were studied in detail. The half-life of (18)F was found to be (109.72�0.19) min. The result is in a good agreement with the recommended value of (109.728�0.019) min evaluated at the Laborotaire National Henri Becquerel (LNHB). PMID:22940412
A demo imaging system based on GaN UV detectors
Yimin Huang; Xiangyang Li; Haimei Gong
Gallium Nitride (GaN) UV detectors have become one of the most important UV detectors for much more compact, more robust, higher quantum efficiency and good stability in higher temperature environment than the traditional detectors. We can evaluate the quality of the detectors by detectivity, responsivity, Signal-to-Noise (the detector with read-out circuit), etc. Although these methods can analyze performance quantificationally, they
ERIC Educational Resources Information Center
Crull, John L.
Provides instructions for making tin can radiation detectors from empty aluminum cans, aluminum foil, clear plastic, copper wire, silica gel, and fine, unwaxed dental floss put together with tape or glue. Also provides suggestions for activities using the detectors. (JN)
Segmented pyroelector detector
Stotlar, S.C.; McLellan, E.J.
A pyroelectric detector is described which has increased voltage output and improved responsivity over equivalent size detectors. The device comprises a plurality of edge-type pyroelectric detectors which have a length which is much greater than the width of the segments between the edge-type electrodes. External circuitry connects the pyroelectric detector segments in parallel to provide a single output which maintains 50 ohm impedance characteristics.
Coated Fiber Neutron Detector Test
Lintereur, Azaree T.; Ely, James H.; Kouzes, Richard T.; Stromswold, David C.
Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Reported here are the results of tests of the 6Li/ZnS(Ag)-coated non-scintillating plastic fibers option. This testing measured the required performance for neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Innovative American Technology (IAT).
Ohlinger, R.D.; Humphrey, H.W.
A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.
V. M. Abazov; B. Abbott; M. Abolins; B. S. Acharya; D. L. Adams; M. Adams; T. Adams; M. Agelou; J.-L. Agram; S. N. Ahmed; S. H. Ahn; M. Ahsan; G. D. Alexeev; G. Alkhazov; A. Alton; G. Alverson; G. A. Alves; M. Anastasoaie; T. Andeen; J. T. Anderson; S. Anderson; B. Andrieu; R. Angstadt; V. Anosov; Y. Arnoud; M. Arov; A. Askew; B. �sman; A. C. S. Assis Jesus; O. Atramentov; C. Autermann; C. Avila; L. Babukhadia; T. C. Bacon; F. Badaud; A. Baden; S. Baffioni; L. Bagby; B. Baldin; P. W. Balm; P. Banerjee; S. Banerjee; E. Barberis; O. Bardon; W. Barg; P. Bargassa; P. Baringer; C. Barnes; J. Barreto; J. F. Bartlett; U. Bassler; M. Bhattacharjee; M. A. Baturitsky; D. Bauer; A. Bean; B. Baumbaugh; S. Beauceron; M. Begalli; F. Beaudette; M. Begel; A. Bellavance; S. B. Beri; G. Bernardi; R. Bernhard; I. Bertram; M. Besan�on; A. Besson; R. Beuselinck; D. Beutel; V. A. Bezzubov; P. C. Bhat; V. Bhatnagar; M. Binder; C. Biscarat; A. Bishoff; K. M. Black; I. Blackler; G. Blazey; F. Blekman; S. Blessing; D. Bloch; U. Blumenschein; E. Bockenthien; V. Bodyagin; A. Boehnlein; O. Boeriu; T. A. Bolton; P. Bonamy; D. Bonifas; F. Borcherding; G. Borissov; K. Bos; T. Bose; C. Boswell; M. Bowden; A. Brandt; G. Briskin; R. Brock; G. Brooijmans; A. Bross; N. J. Buchanan; D. Buchholz; M. Buehler; V. Buescher; S. Burdin; S. Burke; T. H. Burnett; E. Busato; C. P. Buszello; D. Butler; J. M. Butler; J. Cammin; S. Caron; J. Bystricky; L. Canal; F. Canelli; W. Carvalho; B. C. K. Casey; D. Casey; N. M. Cason; H. Castilla-Valdez; S. Chakrabarti; D. Chakraborty; K. M. Chan; A. Chandra; D. Chapin; F. Charles; E. Cheu; L. Chevalier; E. Chi; R. Chiche; D. K. Cho; R. Choate; S. Choi; B. Choudhary; S. Chopra; J. H. Christenson; T. Christiansen; L. Christofek; I. Churin; G. Cisko; D. Claes; A. R. Clark; B. Cl�ment; C. Cl�ment; Y. Coadou; D. J. Colling; L. Coney; B. Connolly; M. Cooke; W. E. Cooper; D. Coppage; M. Corcoran; J. Coss; A. Cothenet; M.-C. Cousinou; B. Cox; S. Cr�p�-Renaudin; M. Cristetiu; M. A. C. Cummings; D. Cutts; H. da Motta; M. Das; B. Davies; G. Davies; G. A. Davis; W. Davis; K. de; P. de Jong; S. J. de Jong; E. De La Cruz-Burelo; C. De La Taille; C. De Oliveira Martins; S. Dean; J. D. Degenhardt; F. D�liot; P. A. Delsart; K. Del Signore; R. Demaat; M. Demarteau; R. Demina; P. Demine; D. Denisov; S. P. Denisov; S. Desai; H. T. Diehl; M. Diesburg; M. Doets; M. Doidge; H. Dong; S. Doulas; L. V. Dudko; L. Duflot; S. R. Dugad; A. Duperrin; O. Dvornikov; J. Dyer; A. Dyshkant; M. Eads; D. Edmunds; T. Edwards; J. Ellison; J. Elmsheuser; J. T. Eltzroth; V. D. Elvira; S. Eno; P. Ermolov; O. V. Eroshin; J. Estrada; D. Evans; H. Evans; A. Evdokimov; V. N. Evdokimov; J. Fagan; J. Fast; S. N. Fatakia; D. Fein; L. Feligioni; A. V. Ferapontov; T. Ferbel; M. J. Ferreira; F. Fiedler; F. Filthaut; W. Fisher; H. E. Fisk; I. Fleck; T. Fitzpatrick; E. Flattum; F. Fleuret; R. Flores; J. Foglesong; M. Fortner; H. Fox; C. Franklin; W. Freeman; S. Fu; S. Fuess; T. Gadfort; C. F. Galea; E. Gallas; E. Galyaev; M. Gao; C. Garcia; A. Garcia-Bellido; J. Gardner; V. Gavrilov; A. Gay; P. Gay; D. Gel�; R. Gelhaus; K. Genser; C. E. Gerber; Y. Gershtein; D. Gillberg; G. Geurkov; G. Ginther; B. Gobbi; K. Goldmann; T. Golling; N. Gollub; V. Golovtsov; B. G�mez; G. Gomez; R. Gomez; R. Goodwin; Y. Gornushkin; K. Gounder; A. Goussiou; D. Graham; G. Graham; P. D. Grannis; K. Gray; S. Greder; D. R. Green; J. Green; H. Greenlee; Z. D. Greenwood; E. M. Gregores; S. Grinstein; Ph. Gris; J.-F. Grivaz; L. Groer; S. Gr�nendahl; M. W. Gr�newald; W. Gu; J. Guglielmo; A. Gupta; S. N. Gurzhiev; G. Gutierrez; P. Gutierrez; A. Haas; N. J. Hadley; E. Haggard; H. Haggerty; S. Hagopian; I. Hall; R. E. Hall; C. Han; L. Han; R. Hance; K. Hanagaki; P. Hanlet; S. Hansen; K. Harder; A. Harel; R. Harrington; J. M. Hauptman; R. Hauser; C. Hays; J. Hays; E. Hazen; T. Hebbeker; C. Hebert; D. Hedin; J. M. Heinmiller; A. P. Heinson; U. Heintz; C. Hensel; G. Hesketh; M. D. Hildreth; R. Hirosky; J. D. Hobbs; B. Hoeneisen; M. Hohlfeld; S. J. Hong; R. Hooper; S. Hou; P. Houben; Y. Hu; J. Huang; Y. Huang; V. Hynek; D. Huffman; I. Iashvili; R. Illingworth; A. S. Ito; S. Jabeen; Y. Jacquier; M. Jaffr�; S. Jain; V. Jain; K. Jakobs; R. Jayanti; A. Jenkins; R. Jesik; Y. Jiang; K. Johns; M. Johnson; P. Johnson; A. Jonckheere; P. Jonsson; H. J�stlein; N. Jouravlev; M. Juarez; A. Juste; A. P. Kaan; M. M. Kado; D. K�fer; W. Kahl; S. Kahn; E. Kajfasz; A. M. Kalinin; J. Kalk; S. D. Kalmani; D. Karmanov; J. Kasper; I. Katsanos; D. Kau; R. Kaur; Z. Ke; R. Kehoe; S. Kermiche; S. Kesisoglou; A. Khanov; A. Kharchilava; Y. M. Kharzheev; H. Kim; K. H. Kim; T. J. Kim; N. Kirsch; B. Klima; M. Klute; J. M. Kohli; J.-P. Konrath; E. V. Komissarov; M. Kopal; V. M. Korablev; A. Kostritski; J. Kotcher; B. Kothari; A. V. Kotwal; A. Koubarovsky; A. V. Kozelov; J. Kozminski; A. Kryemadhi; O. Kouznetsov
The D� experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward
Low Timing Jitter Detector for Gigahertz Quantum Key Distribution
R. J. Collins; R. H. Hadfield; V. Fernandez; S. W. Nam; G. S. Buller
A superconducting single-photon detector based on a niobium nitride nanowire is demonstrated in an optical-fibre-based quantum key distribution test bed operating at a clock rate of 3.3 GHz and a transmission wavelength of 850 nm. The low jitter of the detector leads to significant reduction in the estimated quantum bit error rate and a resultant improvement in the secrecy efficiency compared to previous estimates made by use of silicon single-photon avalanche detectors.
The vertex detector for the Lepton/Photon collaboration
Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)
The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.
Fabrication and Characterization of Superconducting NbN Nanowire Single Photon Detectors
NASA Technical Reports Server (NTRS)
Stern, Jeffrey A.; Farr, William H.
We report on the fabrication and characterization of high-speed, single photon detectors using superconducting NbN nanowires at a wavelength of 1064 nm. A 15 by 15 micron detector with a detector efficiency of 40% has been measured. Due to kinetic inductance, the recovery time of such large area detectors is longer than that of smaller or single wire detectors. The recovery time of our detectors (50 ns) has been characterized by measuring the inter-arrival time statistics of our detector.
Wilson, Tiffany M.S; King, Michael J.; Doty, F. Patrick
This work demonstrated the feasibility and limitations of semiconducting {pi}-conjugated organic polymers for fast neutron detection via n-p elastic scattering. Charge collection in conjugated polymers in the family of substituted poly(p-phenylene vinylene)s (PPV) was evaluated using band-edge laser and proton beam ionization. These semiconducting materials can have high H/C ratio, wide bandgap, high resistivity and high dielectric strength, allowing high field operation with low leakage current and capacitance noise. The materials can also be solution cast, allowing possible low-cost radiation detector fabrication and scale-up. However, improvements in charge collection efficiency are necessary in order to achieve single particle detection with a reasonable sensitivity. The work examined processing variables, additives and environmental effects. Proton beam exposure was used to verify particle sensitivity and radiation hardness to a total exposure of approximately 1 MRAD. Conductivity exhibited sensitivity to temperature and humidity. The effects of molecular ordering were investigated in stretched films, and FTIR was used to quantify the order in films using the Hermans orientation function. The photoconductive response approximately doubled for stretch-aligned films with the stretch direction parallel to the electric field direction, when compared to as-cast films. The response was decreased when the stretch direction was orthogonal to the electric field. Stretch-aligned films also exhibited a significant sensitivity to the polarization of the laser excitation, whereas drop-cast films showed none, indicating improved mobility along the backbone, but poor {pi}-overlap in the orthogonal direction. Drop-cast composites of PPV with substituted fullerenes showed approximately a two order of magnitude increase in photoresponse, nearly independent of nanoparticle concentration. Interestingly, stretch-aligned composite films showed a substantial decrease in photoresponse with increasing stretch ratio. Other additives examined, including small molecules and cosolvents, did not cause any significant increase in photoresponse. Finally, we discovered an inverse-geometric particle track effect wherein increased track lengths created by tilting the detector off normal incidence resulted in decreased signal collection. This is interpreted as a trap-filling effect, leading to increased carrier mobility along the particle track direction. Estimated collection efficiency along the track direction was near 20 electrons/micron of track length, sufficient for particle counting in 50 micron thick films.
Improving the spectral resolution of a highly pixelated detector by applying a pixel-by-pixel energy calibration for investigating the spectral properties of the anode heel effect
NASA Astrophysics Data System (ADS)
Sievers, P.; Klammer, J.; Michel, T.; Hupe, O.; Anton, G.
The energy deposition spectrum measured with highly pixelated photon-counting pixel detectors with a semiconductor sensor layer (e.g. silicon) differs significantly from the impinging X-ray spectrum. This is the main disadvantage compared to commonly known X-ray spectrometers, e.g. high purity Germanium (hpGe) detector. On the other hand, those hpGe-detectors have a lack of spatial resolution and can not be used for energy-resolved imaging. In case of measurements with highly pixelated detectors, a set of monoenergetic detector response functions is needed for the deconvolution of the measured distribution into the impinging spectrum. We have investigated the possibility of applying a pixel-by-pixel calibration on a highly pixelated detector for gaining a higher energy resolution and for lowering the minimal flux needed for the deconvolution. As a result it is now possible to utilize small ROIs of the pixel matrix for the deconvolution. With this analysis method the detector enables spectral X-ray imaging of high photon rates. This is in particular shown for the angular dependency of the anode heel effect on the emitted spectrum.
A multilayer surface detector for ultracold neutrons
Wang, Zhehui; Callahan, N B; Adamek, E R; Bacon, J D; Blatnik, M; Brandt, A E; Broussard, L J; Clayton, S M; Cude-Woods, C; Currie, S; Dees, E B; Ding, X; Gao, J; Gray, F E; Hoffbauer, M A; Holley, A T; Ito, T M; Liu, C -Y; Makela, M; Ramsey, J C; Pattie,, R W; Salvat, D J; Saunders, A; Schmidt, D W; Schulze, R K; Seestrom, S J; Sharapov, E I; Sprow, A; Tang, Z; Wei, W; Wexler, J W; Womack, T L; Young, A R; Zeck, B A
A multilayer surface detector for ultracold neutrons (UCNs) is described. The top $^{10}$B layer is exposed to the vacuum chamber and directly captures UCNs. The ZnS:Ag layer beneath the $^{10}$B layer is a few microns thick, which is sufficient to detect the charged particles from the $^{10}$B(n,$\\alpha$)$^7$Li neutron-capture reaction, while thin enough so that ample light due to $\\alpha$ and $^7$Li escapes for detection by photomultiplier tubes. One-hundred-nm thick $^{10}$B layer gives high UCN detection efficiency, as determined by the mean UCN kinetic energy, detector materials and others. Low background, including negligible sensitivity to ambient neutrons, has also been verified through pulse-shape analysis and comparisons with other existing $^3$He and $^{10}$B detectors. This type of detector has been configured in different ways for UCN flux monitoring, development of UCN guides and neutron lifetime research.
Newman, D.D.
A portable microwave leakage detector comprises a dipole antenna and a hot carrier diode connected in parallel with a light emitting diode, the circuit incorporating minimum solder joints and affording maximum sensitivity without moving parts such that the detector circuit does not decay with time. The dipole antenna is oriented diagonally in a detector case so that the user of the detector automatically presents the antenna to the radiating microwave field (or leakage field) at a maximum receiving attitude with respect to the field. The detector can be utilized to determine whether a microwave oven or any other device is leaking radiation beyond limits imposed by the food and drug administration.
DQE as detection probability of the radiation detectors
Giovanni Zanella
In this paper it is shown that quantum efficiency (DQE), as commonly defined for imaging detectors, can be extended to all radiation detectors with the meaning of detection probability, if Poisson statistics applies. This unified approach is possible in time-domain at zero spatial-frequency.
Special Nuclear Material Detection with a Water Cherenkov based Detector
Sweany, M; Bernstein, A; Bowden, N; Dazeley, S; Svoboda, R
Fission events from Special Nuclear Material (SNM), such as highly enriched uranium or plutonium, produce a number of neutrons and high energy gamma-rays. Assuming the neutron multiplicity is approximately Poissonian with an average of 2 to 3, the observation of time correlations between these particles from a cargo container would constitute a robust signature of the presence of SNM inside. However, in order to be sensitive to the multiplicity, one would require a high total efficiency. There are two approaches to maximize the total efficiency; maximizing the detector efficiency or maximizing the detector solid angle coverage. The advanced detector group at LLNL is investigating one way to maximize the detector size. We are designing and building a water Cerenkov based gamma and neutron detector for the purpose of developing an efficient and cost effective way to deploy a large solid angle car wash style detector. We report on our progress in constructing a larger detector and also present preliminary results from our prototype detector that indicates detection of neutrons.
Spectrometric characteristic improvement of CdTe detectors
V. I. Ivanov; V. A. Garbusin; P. G. Dorogov; A. E. Loutchanski; V. V. Kondrashov
A new pulse shape correction method combined with a pulse shape selection method has been proposed for a CdTe detectors energy resolution improvement and increasing the total absorption peak efficiency. The capabilities of the new technique for the spectrometric characteristic improvement are based on using specific features of the CdTe detectors output pulses. The energy resolution of about 1% FWHM
Development of cryogenic tracking detectors for very high luminosity experiments
J. H�rk�nen; P. Anbinderis; T. Anbinderis; R. Bates; W. de Boer; E. Borchi; M. Bruzzi; C. Buttar; W. Chen; V. Cindro; S. Czellar; V. Eremin; A. Furgeri; E. Gaubas; E. Heijne; I. Ilyashenko; V. Kalesinskas; M. Krause; Z. Li; P. Luukka; I. Mandic; D. Menichelli; M. Mikuz; O. Militaru; S. Mueller; T. O. Niinikoski; V. O�Shea; C. Parkes; K. Piotrzkowski; S. Pirollo; P. Pusa; J. R�is�nen; X. Rouby; E. Tuominen; E. Tuovinen; J. Vaitkus; E. Verbitskaya; S. V�yrynen; M. Zavrtanik
Experimental results and simulations of Charge Collection Efficiency (CCE) of Current Injected Detectors (CIDs) are focused. CID is a concept where the current is limited by the space charge. The injected carriers will be trapped by the deep levels. This induces a stable electric field through the entire bulk regardless of the irradiation fluence the detector has been exposed. Our
Noise immunity of square-law detector-discriminators
Iu. P. Oserskii; A. I. Fedosova
Conditions for obtaining maximum useful-signal amplitude and maximum SNR at the outputs of two types of square-law detector-discriminators are determined. The signal filtering efficiency (pulsed signal on white noise) of this type of device is compared with that of a system consisting of a single oscillatory circuit with optimal bandpass and square-law amplitude detector.
The role of contacts in semiconductor gamma radiation detectors
Uri Lachish
It is proposed that the operation of semiconductor gamma radiation detectors, equipped with ohmic contacts, which allow free electron flow between the contacts and bulk material, will not be sensitive to low hole mobility, hole collection efficiency, or hole trapping. Such fast-operating detectors may be readily integrated into monolithic arrays. The detection mechanism and various material aspects are discussed and
Method for mapping charge pulses in semiconductor radiation detectors
T. H. Prettyman
An efficient method for determining the distribution of charge pulses produced by semiconductor detectors is presented. The method is based on a quasi-steady-state model for semiconductor detector operation. A complete description of the model and the underlying assumptions are given. Mapping of charge pulses is accomplished by solving an adjoint carrier continuity equation. The solution of the adjoint equation yields
Theoretical framework for mapping pulse shapes in semiconductor radiation detectors
T. H. Prettyman
An efficient method for calculating of charge pulses produced by semiconductor detectors is presented. The method is based on a quasi-steady-state model for semiconductor detector operation. A complete description of the model and underlying assumptions is given. Mapping of charge pulses is accomplished by solving an adjoint carrier continuity equation. The solution of the adjoint equation yields Green's function, a
Throughput of Coded Optical CDMA Systems with AND Detectors
NASA Astrophysics Data System (ADS)
Memon, Kehkashan A.; Umrani, Fahim A.; Umrani, A. W.; Umrani, Naveed A.
Conventional detection techniques used in optical code-division multiple access (OCDMA) systems are not optimal and result in poor bit error rate performance. This paper analyzes the coded performance of optical CDMA systems with AND detectors for enhanced throughput efficiencies and improved error rate performance. The results show that the use of AND detectors significantly improve the performance of an optical channel.
Cs based photocathodes for gaseous detectors
Borovick-Romanov, A. [Inst. for Physical Problems (Russian Federation); Peskov, V. [Fermi National Accelerator Lab., Batavia, IL (United States)
We demonstrated that some standard photocathodes SbCs, GaAs(Cs), Au(Cs) can easily be manufactured for use inside gaseous detectors. When filed with clean quenched gases such detectors have a quantum efficiency of a few percent in the visible region of the spectra and can operate at a gain >10{sup 3}. We tried to make these photocathodes more air stable by protecting their surfaces with a thin layer of CsI or liquid TMAE. The most air stable were photocathodes with a CsI protective layer. A wavelengths {le}185 nm such photocathodes have the highest quantum efficiency among all known air stable photocathodes, including CsI. Gaseous detectors with such photocathodes can operate at a gain of 10{sup 5}. Results of first tests of doped CsI photocathode are also presented. Possible fields of application of new photocathodes are discussed.
A test facility to calibrate EUV detectors.
NASA Astrophysics Data System (ADS)
Bonanno, G.; Naletto, G.; Tondello, G.
A new test facility has been realized in the authors' laboratories to calibrate detectors in the ultraviolet region between 300 � and 2500 �. It consists of a vacuum normal incidence Johnson-Onaka monochromator with a set of interchangeable gratings and several UV lamps to optimally cover the whole spectral range. A pair of NIST calibrated photodiodes allows an absolute measurement of the photon flux outcoming from the monochromator, and thus it is possible to evaluate the quantum efficiency of the detectors under test. Moreover, other characteristic parameter of UV detectors can be evaluated, like for example the spatial resolution and the uniformity response. The results of the quantum efficiency measurements of an EEV ion implanted CCD are shown. Finally, the possible improvements necessary to optimize this test facility are discussed.
Ion Technique for Identifying Gamma Detector Candidates
Zhang, Yanwen; Xiang, Xia; Rausch, Julie L.; Zu, Xiaotao T.; Weber, William J.
Recent demands for radiation detector materials with better energy resolution at room temperature have prompted research efforts on both accelerated material discovery and efficient analysis techniques. Ions can easily deposit their energy in thin films or small crystals and the radiation response can be used to identify material properties relevant to detector performance. In an effort to identify gamma detector candidates using small crystals or film samples, an ion technique is developed to measure relative light yield and energy resolution of candidate materials and to evaluate radiation detection performance. Employing a unique time-of-flight (TOF) telescope, light yield and energy resolution resulting from ion excitation are investigated over a continuous energy region. The efficiency of this ion technique is demonstrated using both organic (plastic scintillator) and inorganic (CaF2:Eu, YAP:Ce, CsI:Tl and BGO) scintillators.
Bolotnikov, Aleksey E. (South Setauket, NY); Camarda, Giuseppe (Farmingville, NY); Cui, Yonggang (Upton, NY); James, Ralph B. (Ridge, NY)
The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.
Independent Detector Testing Laboratory Don Figer, Mike Regan, Bernard Rauscher
Figer, Donald F.
types, using the same procedures, setups, dewars, light sources, targets, electronics, acquisition. The read noise was low, devices-order detector properties (read noise, dark current, persistence, quantum efficiency, etc.) as functions
Carbon Nanotube Terahertz Detector Xiaowei He,,
Natelson, Douglas
-efficiency solar cells.4-6 THz detectors are required for a wide range of applications in astronomy, sensing and collective antenna effects, and suggest that judicious design of thermal management and quantum engineering of outstanding electronic and photonic properties,1-7 including those ideally suited for terahertz (THz) devices
Asymptotic performance measures for sequential partition detectors
R. Dwyer
It is known that the sequential probability ratio test (SPRT) minimizes the average detection time among all tests for fixed type I and type II errors under the hypothesis and alternative. Often, in practical detection problems, the signal level is unknown during the decision interval. In this paper, the relative efficiency of a sequential detector is compared with its fixed
Performance of the BELLE silicon vertex detector
R. Abe; H. Aihara; G. Alimonti; Y. Asano; A. Bakich; E. Banas; A. Bozek; T. Browder; J. Dragic; C. Everton; C. Fukunaga; A. Gordon; H. Guler; J. Haba; K. Hara; T. Hara; N. Hastings; M. Hazumi; E. Heenan; T. Higuchi; T. Hojo; H. Ishino; G. Iwai; P. Jalocha; J. Kaneko; P. Kapusta; T. Kawasaki; K. Korotuschenko; J. S. Lange; Y. Li; D. Marlow; T. Matsubara; H. Miyake; L. Moffitt; G. Moloney; S. Mori; Y. Nagshima; T. Nakadaira; T. Nakamura; Z. Natkaniec; S. Okuno; S. Olsen; W. Ostrowicz; H. Palka; L. Peak; M. Rozanska; J. Ryuko; M. Sevior; K. Shimada; K. Sumisawa; S. Stanic; R. Stock; S. Swain; H. Tagomori; H. Tajima; S. Takahashi; F. Takasaki; N. Tamura; J. Tanaka; M. Tanaka; G. Taylor; T. Tomura; K. Trabelsi; T. Tusboyama; Y. Tsujita; G. Varner; K. Varvell; H. Yamamoto; Y. Watanabe; Y. Yamada; M. Yokoyama; H. Zhao; D. Zontar
Using 6.8 fb-1 of data taken between October 1999 and July 2000, the performance of the silicon vertex detector (SVD) in the BELLE experiment is reviewed. The main purpose of the SVD is to make precise measurements of the B decay vertex position, which are essential for the observation of CP asymmetries. Excellent vertex resolution and a good detection efficiency
Josephson junctions as microwave heterodyne detectors
Y. Taur
The properties of point contact Josephson junctions operated as 36 GHz heterodyne detectors have been extensively studied. The measured performance is in good agreement with the theory developed for microwave coupling, conversion efficiency, and intrinsic noise based on the resistively shunted junction model. A tunable cavity matching structure was designed to obtain good RF coupling to the point contact. By
Radiometric calibration of single photon detectors by a single photon source based on NV-centers in diamond
W. Schmunk; M. Rodenberger; S. Peters; H. Hofer; S. K�ck
A widespread use of various relative calibration techniques is established in order to realize reliable and low uncertainty measurements of the detection efficiency, which is one key parameter characterizing single photon detectors. In the following paper we will present an approach to evaluate the relative detection efficiency of single photon avalanche photo diode (SPAD) detectors compared to a standard detector.
Explosives (and other threats) detection using pulsed neutron interrogation and optimized detectors
NASA Astrophysics Data System (ADS)
Strellis, Dan A.; Elsalim, Mashal; Gozani, Tsahi
We have previously reported results from a human-portable system using neutron interrogation to detect contraband and explosives. We summarized our methodology for distinguishing threat materials such as narcotics, C4, and mustard gas in the myriad of backgrounds present in the maritime environment. We are expanding our mission for the Domestic Nuclear Detection Office (DNDO) to detect Special Nuclear Material (SNM) through the detection of multiple fission signatures without compromising the conventional threat detection performance. This paper covers our initial investigations into using neutrons from compact pulsed neutron generators via the d(D,n)3He or d(T,n)? reactions with energies of ~2.5 and 14 MeV, respectively, for explosives (and other threats) detection along with a variety of gamma-ray detectors. Fast neutrons and thermal neutrons (after successive collisions) can stimulate the emission of various threat detection signatures. For explosives detection, element-specific gamma-ray signatures via the (n,n'?) inelastic scattering reaction and the (n,'?) thermal capture reaction are detected. For SNM, delayed gamma-rays following fission can be measured with the same detector. Our initial trade-off investigations of several gamma-ray detectors types (NaI, CsI, LaBr3, HPGe) for measuring gamma-ray signatures in a pulsed neutron environment for potential application in a human-portable active interrogation system are covered in this paper.
Can scintillation detectors with low spectral resolution accurately determine radionuclides content of building materials?
Kovler, K; Prilutskiy, Z; Antropov, S; Antropova, N; Bozhko, V; Alfassi, Z B; Lavi, N
The current paper makes an attempt to check whether the scintillation NaI(Tl) detectors, in spite of their poor energy resolution, can determine accurately the content of NORM in building materials. The activity concentrations of natural radionuclides were measured using two types of detectors: (a) NaI(Tl) spectrometer equipped with the special software based on the matrix method of least squares, and (b) high-purity germanium spectrometer. Synthetic compositions with activity concentrations varying in a wide range, from 1/5 to 5 times median activity concentrations of the natural radionuclides available in the earth crust and the samples of popular building materials, such as concrete, pumice and gypsum, were tested, while the density of the tested samples changed in a wide range (from 860 up to 2,410 kg/m(3)). The results obtained in the NaI(Tl) system were similar to those obtained with the HPGe spectrometer, mostly within the uncertainty range. This comparison shows that scintillation spectrometers equipped with a special software aimed to compensate for the lower spectral resolution of NaI(Tl) detectors can be successfully used for the radiation control of mass construction products. PMID:23542118
Radiation Effect On Gas Electron Multiplier Detector Performance
Park, Kwang June [Korean Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Baldeloma, Edwin; Park, Seongtae; White, Andrew P.; Yu, Jaehoon [Department of Physics, University of Texas at Arlington, Arlington TX 76019 (United States)
Gas Electron Multiplier (GEM) detector is a gas device with high gain and high efficiency. These detectors use chemically perforated 65 {mu}m thick copper clad Kapton polyimide foils. Given its potential for detecting X-rays and other radiations, GEM detectors may be used in an environment with high radioactivity. The Kapton foils manufacturer, Du Pont Inc., claims that the foils are radioactive resistant. To verify whether the GEM detector performance is affected by the exposure to radiation, several GEM foils were irradiated to a {sup 60}Co source at the gamma-ray irradiation facility at Sterigenics, Tustin, CA. Four sets of GEM foils were exposed to the level of 10 kGy, 100 kGy, 1,000 kGy and 10,000 kGy. The output signal from the GEM detectors with irradiated GEM foils were measured and compared to the detector with no irradiation. We observed that the shapes of the peaks from 5.9 KeV {sup 55}Fe X-ray were distorted and that the detector gain increased compared to that of the un-irradiated detector. In particular, the detector with 10,000 kGy irradiation appeared to have the biggest peak distortion and increased gain. It was also found from that additional electrons from radiation-induced free radicals in the Kapton film contribute to output signal of the irradiated GEM detectors. Further studies are needed to explain the mechanism of these detector performance changes.
Calibration of single-photon detectors using quantum statistics
Mogilevtsev, D. [Institute of Physics, Belarus National Academy of Sciences, F.Skarina Ave. 68, Minsk 220072 (Belarus) and Instituto de Fisica, UNICAMP, CP 6165, Campinas-SP, 13083-970 (Brazil)
I show that calibration of the single-photon detector can be performed without knowledge of the signal parameters. Only partial information about the state statistics is sufficient for that. If one knows that the state is the squeezed one or the squeezed one mixed with the incoherent radiation, one can infer both the parameters of the state and the efficiency of the detector. For that one needs only to measure on/off statistics of detector clicks for the number of known absorbers placed before the detector. Thus, I suggest a scheme that performs a tomography of the signal and the measuring apparatus simultaneously.
First sensitivity limits of the ALPS TES detector
Jan Dreyling-Eschweiler; for the ALPS-II collaboration
The Any Light Particle Search II (ALPS II) requires a sensitive detection of 1064 nm photons. Thus, a low dark count rate (DC) and a high detection efficiency (DE) is needed. ALPS has set up a transition-edge sensor (TES) detector system, namely the ALPS TES detector. It is found that thermal photons from room temperature surfaces are the main contribution of dark counts for 1064 nm photon signals. Furthermore, the current setup of the ALPS TES detector shows an improvement compared to using the ALPS I detector.
GaN-based PIN alpha particle detectors
NASA Astrophysics Data System (ADS)
Wang, Guo; Fu, Kai; Yao, Chang-sheng; Su, Dan; Zhang, Guo-guang; Wang, Jin-yan; Lu, Min
GaN-based PIN alpha particle detectors are studied in this article. The electrical properties of detectors have been investigated, such as current-voltage ( I- V) and capacitance-voltage ( C- V). The reverse current of all detectors is in nA range applied at 30 V, which is suitable for detector operation. The charge collection efficiency (CCE) is measured to be approximately 80% but the energy resolution is calculated to be about 40% mostly because the intrinsic layer is not sufficiently thick enough.
Status of the D0 fiber tracker and preshower detectors
Smirnov, Dmitri; /Notre Dame U.; ,
In this report we focus on the performance of the D0 central fiber tracker and preshower detectors during the high luminosity p{bar p} collisions at {radical}s = 1.96 GeV delivered by the Tevatron collider at Fermilab (Run IIb). Both fiber tracker and preshower detectors utilize a similar readout system based on high quantum efficiency solid state photo-detectors capable of converting light into electrical signals. We also give a brief description of the D0 detector and the central track trigger, and conclude with a summary on the central tracker performance.
The ATLAS Inner Detector operation, data quality and tracking performance
Stanecka, E
The ATLAS Inner Detector is responsible for particle tracking in ATLAS experiment at CERN Large Hadron Collider (LHC) and comprises silicon and gas based detectors. The combination of both silicon and gas based detectors provides high precision impact parameter and momentum measurement of charged particles, with high efficiency and small fake rate. The ID has been used to exploit fully the physics potential of the LHC since the first proton-proton collisions at 7 TeV were delivered in 2009. The performance of track and vertex reconstruction is presented, as well as the operation aspects of the Inner Detector and the data quality during the many months of data taking.
The ATLAS Inner Detector operation, data quality and tracking performance
Ewa Stanecka; on behalf of the ATLAS Collaboration
The ATLAS Inner Detector is responsible for particle tracking in ATLAS experiment at CERN Large Hadron Collider (LHC) and comprises silicon and gas based detectors. The combination of both silicon and gas based detectors provides high precision impact parameter and momentum measurement of charged particles, with high efficiency and small fake rate. The ID has been used to exploit fully the physics potential of the LHC since the first proton-proton collisions at 7 TeV were delivered in 2009. The performance of track and vertex reconstruction is presented, as well as the operation aspects of the Inner Detector and the data quality during the many months of data taking.
Assessing CZT detector performance for environmental radioactivity investigations.
Rahman, Rubina; Plater, A J; Nolan, P J; Appleby, P G
Cadmium zinc telluride (CdZnTe or CZT) is the leading semiconductor detector for gamma spectroscopy at room temperature. In the present study, a coplanar-grid CZT detector was used for gamma-ray measurements of environmental radioactivity on a contaminated saltmarsh sediment core in comparison with results from a coaxial high-purity germanium detector to assess their comparative performance. The findings reveal that the CZT performs well for both (241)Am and (137)Cs measurements over a broad range of activities, despite limited detector efficiency, and can be used to good effect in the study of environmental radioactivity in contaminated estuarine settings. PMID:23060429
Effect of the heralding detector properties on the conditional generation of single-photon states
Paris-Sud XI, Université de
on the heralding detector properties, such as its quantum efficiency, noise or photon-number resolution ability a detailed analysis of the experimental characterization of these detectors [6] and of the modeling to determine the fidelity and preparation rate for the two heralding detectors, as a function of the noise
Learning Detectors from Large Datasets for Object Retrieval in Video Surveillance Rogerio Feris, Sharath Pankanti
Davis, Larry
solutions for this problem can be obtained by learning detectors from huge amounts of training data. Along set and learning a large array of complementary, compact, deep cascade detectors. At test time, given of training data to learn robust and efficient multi-view object detectors. Different from other multimedia
GaAs solid state detectors for physics at the LHC
S. P. Beaumont; R. Bertin; A. Zichichi; C. N. Booth; C. Buttar; F. H. Combley; M. Dogru; Y. Hou; L. Carraresi; M. Colocci; A. Francescato; M. Nuti; P. G. Peifer; N. Tartoni; V. Vanni; A. Vinattieri; F. Cindolo; S. D. Auria; C. del Papa; F. Fiori; B. Lisowski; V. OShea; M. Edwards; P. H. Seller; K. Shankar; P. H. Sharp; F. Nava; P. Ottaviani; J. G. Lynch; J. Matheson; C. Raine; I. O. Skillicorn; K. M. Smith; I. ten Have; R. M. Turbull; F. Foster; B. Jones
Progress with Schottky diode and p i n diode GaAs detectors for minimum ionizing particles is reported here. The radiation hardness and potential speed of simple diodes is shown to be more than competitive with silicon detectors. A discussion is given of the present understanding of the charge transport mechanism in the detectors as it influences their charge collection efficiency.
Charge transport properties of undoped SI LEC GaAs solid-state detectors
S. P. Beaumont; R. Bertin; C. N. Booth; M. Bruzzi; C. Buttar; L. Carraresi; F. Cindolo; M. Colocci; F. H. Combley; S. D'Auria; S. Degennaro; D. del Papa; M. Dogru; M. Edwards; F. Fiori; F. Foster; A. Francescato; Y. Hou; P. Houston; B. Jones; J. G. Lynch; B. Lisowski; J. Matheson; F. Nava; M. Nuti; V. O'Shea; P. G. Pelfer; M. Pischedda; C. Raine; J. Santana; I. Saunders; P. H. Seller; I. O. Skillikorn; T. Sloan; K. M. Smith; N. Tartoni; I. Ten Have; R. M. Turnbull; A. Vinattieri; A. Zichichi
The GaAs detectors for minimum ionizing particles fabricated with commercial undoped SI GaAs show good quality as minimum ionizing particle detectors. A discussion is given of the present understanding of the charge transport mechanism in the detectors since it influences their charge collection efficiency.
Using induced signals to sense position from a microchannel plate detector
NASA Astrophysics Data System (ADS)
deSouza, R. T.; Gosser, Z. Q.; Hudan, S.
We demonstrate a novel concept for a position sensitive microchannel plate detector. This detector provides sub-millimeter spatial resolution by examining the signal induced on a wire harp by the electron cloud from a microchannel plate detector. Wires in the harp are efficiently read out by coupling them to a delay line.
This lecture will serve as an introduction to particle detectors and detection techniques. In the first lecture, a historic overview of particle detector development will be given. In the second lecture, some basic techniques and concepts for particle detection will be discussed. In the third lecture, the interaction of particles with matter, the basis of particle detection, will be presented. The fourth and fifth lectures will discuss different detector types used for particle tracking, energy measurement and particle identification.
Germanium detector vacuum encapsulation
NASA Technical Reports Server (NTRS)
Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.
This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.
Germanium detector vacuum encapsulation
NASA Astrophysics Data System (ADS)
Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.
This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.
OPTI 566 SPRING 2012 Optical Detectors and Detector Systems
Arizona, University of
analysis of solid- state physics. Following the coverage of detectors and detector arrays, the content sources 38 - 77 (D/B) 3 of x 4 Tue 31 Jan 2012 Thu 02 Feb 2012 Intro to noise Detector Figures of meritOPTI 566 � SPRING 2012 Optical Detectors and Detector Systems Meinel Building, Room 422 Tu & Th, 8
Photocapacitive MIS infrared detectors
NASA Technical Reports Server (NTRS)
Sher, A.; Lu, S. S.-M.; Moriarty, J. A.; Crouch, R. K.; Miller, W. E.
A new class of room-temperature infrared detectors has been developed through use of metal-insulator-semiconductor (MIS) or metal-insulator-semiconductor-insulator-metal (MISIM) slabs. The detectors, which have been fabricated from Si, Ge and GaAs, rely for operation on the electrical capacitance variations induced by modulated incident radiation. The peak detectivity for a 1000-A Si MISIM detector is comparable to that of a conventional Si detector functioning in the photovoltaic mode. Optimization of the photocapacitive-mode detection sensitivity is discussed.
Neutrino factory near detector
NASA Astrophysics Data System (ADS)
Bogomilov, M.; Karadzhov, Y.; Matev, R.; Tsenov, R.; Laing, A.; Soler, F. J. P.
The neutrino factory is a facility for future precision studies of neutrino oscillations. A so-called near detector is essential for reaching the required precision for a neutrino oscillation analysis. The main task of the near detector is to measure the flux of the neutrino beam. Such a high intensity neutrino source like a neutrino factory provides also the opportunity for precision studies of various neutrino interaction processes in the near detector. We discuss the design concepts of such a detector. Results of simulations of a high resolution scintillating fiber tracker show that such a detector is capable of determining the neutrino flux normalization with an uncertainty of less than 1% by measuring pure leptonic interactions. Reconstruction of the neutrino energy in each event and a flux estimation based on the shapes of the neutrino energy spectra are discussed. A full setup of the near detector, consisting of a high granularity vertex detector, high resolution tracker, and muon catcher is also presented. Finally, a method to extrapolate the measured near detector flux to the far detector is shown, demonstrating that it is able to extract the correct values of ?13 and the CP violation phase ? without any significant bias and with high accuracy.
Polycrystalline mercuric iodide detectors
NASA Astrophysics Data System (ADS)
Schieber, Michael M.; Hermon, Haim; Zuck, Asaf; Vilensky, Alexander I.; Melekhov, Leonid; Shatunovsky, Rubil; Meerson, Evgenie; Saado, Yehezkel
The fabrication of polycrystalline HgI2 thick film detectors using the hot wall physical vapor deposition, method is described. The X-ray response of these detectors to a radiological X-ray generator of 60 kVp has been studied using the current integration mode. The response expressed in (mu) A, the dark current expressed in pA/cm2 and sensitivity expressed in (mu) C/R(DOT)cm2 are given for these detectors for several thickness and grain sizes. The optimal sensitivity is compared with published data on the response to X-rays by polycrystalline PbI2 and A-Se detectors.
Study of solid-conversion gaseous detector based on GEM for high energy X-ray industrial CT.
Zhou, Rifeng; Zhou, Yaling
The general gaseous ionization detectors are not suitable for high energy X-ray industrial computed tomography (HEICT) because of their inherent limitations, especially low detective efficiency and large volume. The goal of this study was to investigate a new type of gaseous detector to solve these problems. The novel detector was made by a metal foil as X-ray convertor to improve the conversion efficiency, and the Gas Electron Multiplier (hereinafter "GEM") was used as electron amplifier to lessen its volume. The detective mechanism and signal formation of the detector was discussed in detail. The conversion efficiency was calculated by using EGSnrc Monte Carlo code, and the transport course of photon and secondary electron avalanche in the detector was simulated with the Maxwell and Garfield codes. The result indicated that this detector has higher conversion efficiency as well as less volume. Theoretically this kind of detector could be a perfect candidate for replacing the conventional detector in HEICT. PMID:24865206
Enabling photon counting detectors with dynamic attenuators
NASA Astrophysics Data System (ADS)
Hsieh, Scott S.; Pelc, Norbert J.
Photon-counting x-ray detectors (PCXDs) are being investigated as a replacement for conventional x-ray detectors because they promise several advantages, including better dose efficiency, higher resolution and spectral imaging. However, many of these advantages disappear when the x-ray flux incident on the detector is too high. We recently proposed a dynamic, piecewise-linear attenuator (or beam shaping filter) that can control the flux incident on the detector. This can restrict the operating range of the PCXD to keep the incident count rate below a given limit. We simulated a system with the piecewise-linear attenuator and a PCXD using raw data generated from forward projected DICOM files. We investigated the classic paralyzable and nonparalyzable PCXD as well as a weighted average of the two, with the weights chosen to mimic an existing PCXD (Taguchi et al, Med Phys 2011). The dynamic attenuator has small synergistic benefits with the nonparalyzable detector and large synergistic benefits with the paralyzable detector. Real PCXDs operate somewhere between these models, and the weighted average model still shows large benefits from the dynamic attenuator. We conclude that dynamic attenuators can reduce the count rate performance necessary for adopting PCXDs.
6Li foil thermal neutron detector
Ianakiev, Kiril D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Chung, Kiwhan [Los Alamos National Laboratory; Macarthur, Duncan W [Los Alamos National Laboratory
In this paper we report on the design of a multilayer thermal neutron detector based on {sup 6}Li reactive foil and thin film plastic scintillators. The {sup 6}Li foils have about twice the intrinsic efficiency of {sup 10}B films and about four times higher light output due to a unique combination of high energy of reaction particles, low self absorption, and low ionization density of tritons. The design configuration provides for double sided readout of the lithium foil resulting in a doubling of the efficiency relative to a classical reactive film detector and generating a pulse height distribution with a valley between neutron and gamma signals similar to {sup 3}He tubes. The tens of microns thickness of plastic scintillator limits the energy deposited by gamma rays, which provides the necessary neutron/gamma discrimination. We used MCNPX to model a multilayer Li foil detector design and compared it with the standard HLNCC-II (18 {sup 3}He tubes operated at 4 atm). The preliminary results of the {sup 6}Li configuration show higher efficiency and one third of the die-away time. These properties, combined with the very short dead time of the plastic scintillator, offer the potential of a very high performance detector.
The STIS MAMA status: Current detector performance
NASA Technical Reports Server (NTRS)
Danks, A. C.; Joseph, C.; Bybee, R.; Argebright, V.; Abraham, J.; Kimble, R.; Woodgate, B.
The STIS (Space Telescope Imaging Spectrograph) is a second generation Hubble instrument scheduled to fly in 1997. Through a variety of modes, the instrument will provide spectral resolutions from R approximately 50 in the objective spectroscopy mode to 100,000 in the high resolution echelle mode in the wavelength region from 115 to 1000 nm. In the UV the instrument employs two MAMA (Multimode Anode Microchannel plate Arrays) 1024 by 1024 pixel detectors, which provide high DQE (Detective Quantum Efficiency), and good dynamic range and resolution. The current progress and performance of these detectors are reported, illustrating that the technology is mature and that the performance is very close to flight requirements.
Microdosimetric modelling of the relative efficiency of thermoluminescent materials
Pawe? Olko
Thermoluminescence (TL) dosimetry relies on evaluating the dose absorbed in the TL detector by measuring the light output by the detector, i.e. by the TL glow-curve analysis. However, the absolute efficiency of the TL light emission per unit dose of ionizing radiation absorbed in the detector is known to depend on the energy and quality (ionization density) of this radiation.
Resonant cavity enhanced detectors embedded in photonic crystals
NASA Astrophysics Data System (ADS)
Temelkuran, B.; Ozbay, E.; Kavanaugh, J. P.; Tuttle, G.; Ho, K. M.
We report a resonant cavity enhanced (RCE) detector built around a three-dimensional photonic band gap crystal. The RCE detector was built by placing a monopole antenna within the localized modes of planar and boxlike defect structures. The enhanced electric field around these defect structures were then measured by a microwave detector and a network analyzer. We measured a power enhancement factor of 3450 for planar cavity structures. A Fabry-Perot cavity model was used to understand and predict resonant cavity enhancement in this structure. The tuning bandwidth of the RCE detector extends from 10.5 to 12.8 GHz, which corresponds to the full photonic band gap by the crystal. These RCE detectors have increased sensitivity and efficiency when compared to conventional detectors, and can be used for various applications.
First test of cold edgeless silicon microstrip detectors
Avati, V; Borer, K; Bozzo, M; Capra, R; Casagrande, L; Eggert, Karsten; Heijne, Erik H M; Klauke, S; Li, Z; M�ki, T; Morelli, A; Oljemark, F; Palmieri, V G; Perea-Solano, B; Tapprogge, Stefan
Silicon microstrip detectors will provide the forward tracking in the TOTEM experiment at the LHC. To allow efficient tracking closest to the beam ( approximately equals 1 mm) these detectors should be sensitive up to their physical edge (i.e. edgeless). Edgeless (without guard rings) microstrip planar detectors can be operated at cryogenic temperatures (about 130 degree K) where leakage currents due to the active edge are drastically reduced. A silicon microstrip prototype, cut perpendicular to the strips, has been tested with a pion beam at CERN to study its efficiency close to the edge by using reference tracks from a simple silicon telescope. Results indicate that the detector measures tracks with good efficiency up to the physical edge of the silicon.
Gamma-ray observations of SN 1987A with an array of high-purity germanium detectors
NASA Technical Reports Server (NTRS)
Sandie, W. G.; Nakano, G. H.; Chase, L. F., Jr.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Paciesas, W.
A balloonborne gamma-ray spectrometer comprising an array of high-purity n-type germanium (HPGe) detectors surrounded by an active NaI(T1) collimator and Compton suppressing anticoincidence shield was flown on May 29-30, 1987. The average column depth of residual atmosphere in the direction of SN 1987A at float altitude was 6.3 g/sq cm during the observation. The 3-sigma upper limit obtained for the 1238-keV line from Co-56 is 0.0013 photons/sq cm s. The corresponding limit for the 847-keV line is 0.0017 photons/sq cm s.
Efficient Watermark Detection and Collusion Francis Zane
Zane, Francis
notion of efficiency: What resources does the watermark detector need in order to perform this tracing watermarking algorithm which improves the detector running time from linear to polylogarithmic in the number� tern: For each user, a individual noise pattern (called a watermark) is generated and inserted
Graphene vertical hot-electron terahertz detectors
Ryzhii, V., E-mail: email@example.com [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University and Institute of Ultra High Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow 111005 (Russian Federation); Satou, A.; Otsuji, T. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Mitin, V. [Department of Electrical Engineering, University at Buffalo, Buffalo, New York 1460-1920 (United States); Shur, M. S. [Departments of Electrical, Electronics, and Systems Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)
We propose and analyze the concept of the vertical hot-electron terahertz (THz) graphene-layer detectors (GLDs) based on the double-GL and multiple-GL structures with the barrier layers made of materials with a moderate conduction band off-set (such as tungsten disulfide and related materials). The operation of these detectors is enabled by the thermionic emissions from the GLs enhanced by the electrons heated by incoming THz radiation. Hence, these detectors are the hot-electron bolometric detectors. The electron heating is primarily associated with the intraband absorption (the Drude absorption). In the frame of the developed model, we calculate the responsivity and detectivity as functions of the photon energy, GL doping, and the applied voltage for the GLDs with different number of GLs. The detectors based on the cascade multiple-GL structures can exhibit a substantial photoelectric gain resulting in the elevated responsivity and detectivity. The advantages of the THz detectors under consideration are associated with their high sensitivity to the normal incident radiation and efficient operation at room temperature at the low end of the THz frequency range. Such GLDs with a metal grating, supporting the excitation of plasma oscillations in the GL-structures by the incident THz radiation, can exhibit a strong resonant response at the frequencies of several THz (in the range, where the operation of the conventional detectors based on A{sub 3}B{sub 5} materials, in particular, THz quantum-well detectors, is hindered due to a strong optical phonon radiation absorption in such materials). We also evaluate the characteristics of GLDs in the mid- and far-infrared ranges where the electron heating is due to the interband absorption in GLs.
Y. Kubota; J. K. Nelson; D. Perticone; R. Poling; S. Schrenk; M. S. Alam; Z. H. Bian; D. Chen; I. J. Kim; W. C. Li; X. C. Lou; B. Nemati; C. R. Sun; P.-N. Wang; M. M. Zoeller; G. Crawford; R. Fulton; K. K. Gan; T. Jensen; H. Kagan; R. Kass; R. Malchow; F. Morrow; M. K. Sung; J. Whitmore; P. Wilson; F. Butler; X. Fu; G. Kalbfleisch; M. Lambrecht; P. Skubic; J. Snow; P.-L. Wang; D. Bortoletto; D. N. Brown; W. Y. Chen; J. Dominick; R. L. McIlwain; D. H. Miller; M. Modesitt; E. I. Shibata; S. F. Schaffner; I. P. J. Shipsey; W. M. Yao; M. Battle; H. Kroha; K. Sparks; E. H. Thorndike; C.-H. Wang; R. Stroynowski; M. Artuso; M. Goldberg; T. Haupt; R. Holmes; N. Horwitz; A. Jawahery; P. Lubrano; G. C. Moneti; Y. Rozen; P. Rubin; V. Sharma; T. Skwarnicki; S. Stone; M. Thulasidas; G. Zhu; S. E. Csorna; V. Jain; T. Letson; D. S. Akerib; B. Barish; M. Chadha; D. F. Cowen; G. Eigen; J. S. Miller; J. Urheim; A. J. Weinstein; R. J. Morrison; H. Nelson; J. Richman; H. Tajima; D. Schmidt; M. Witherell; A. Bean; I. Brock; M. Procario; M. Daoudi; W. T. Ford; D. R. Johnson; K. Lingel; M. Lohner; P. Rankin; J. G. Smith; J. Alexander; C. Bebek; K. Berkelman; D. Besson; E. Blucher; T. E. Browder; D. G. Cassel; E. Cheu; D. M. Coffman; R. Desalvo; P. S. Drell; R. Ehrlich; R. S. Galik; M. Garcia-Sciveres; B. Geiser; M. G. D. Gilchriese; B. Gittelman; S. W. Gray; D. L. Hartill; B. K. Heltsley; K. Honschoid; C. Jones; J. Kandaswamy; N. Katayama; P. C. Kim; R. Kowalewski; D. L. Kreinick; G. S. Ludwig; J. Masui; J. Mevissen; N. B. Mistry; J. Mueller; R. Namjoshi; S. Nandi; C. R. Ng; E. Nordberg; C. O'Grady; J. R. Patterson; D. Peterson; M. Pisharody; D. Riley; M. Sapper; M. Selen; H. Worden; M. Worris; F. W�rthwein; P. Avery; A. Freyberger; J. Rodriguez; J. Yelton; T. Bowcock; R. Giles; S. Henderson; K. Kinoshita; F. Pipkin; M. Saulnier; R. Wilson; J. Wolinski; D. Xiao; H. Yamamoto; A. J. Sadoff; R. Ammar; P. Baringer; D. Coppage; R. Davis; P. Haas; M. Kelly; N. Kwak; H. Lam; S. Ro
The new detector for data recording by the CLEO collaboration at the Cornell Electron Storage Ring is described. This detector has been designed to optimize studying e+ e- annihilation into hadronic matter at a total energy of 10 GeV. It consists of high precesion charged particle tracking chambers and an electromagnetic calorimeter together with systems for particle identification. The design
Smoke Detectors and Legislation.
ERIC Educational Resources Information Center
National Fire Prevention and Control Administration (DOC), Washington, DC.
This manual, one of a series for use in public education, provides an in-depth review of the current status of state and local smoke detector legislation. First, for the community considering a smoke detector law or ordinance, six decision points are discussed: which residential occupancy sub-classes will be affected; what the time factors are for�
Scanning Seismic Intrusion Detector
NASA Technical Reports Server (NTRS)
Lee, R. D.
Scanning seismic intrusion detector employs array of automatically or manually scanned sensors to determine approximate location of intruder. Automatic-scanning feature enables one operator to tend system of many sensors. Typical sensors used with new system are moving-coil seismic pickups. Detector finds uses in industrial security systems.
Klaus Moenig
For the superconducting linear collider TESLA a multi purpose detector has been designed. This detector is optimised for the important physics processes expected at a next generation linear collider up to around 1 TeV and is designed for the specific environment of a superconducting collider.
Amorphous silicon radiation detectors
V. Perez-Mendez; S. N. Kaplan
Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of
J. V. Allaby; W. W. Ash; H. R. Band; L. A. Baksay; H. T. Blume; M. Bosman; T. Camporesi; G. B. Chadwick; S. H. Clearwater; R. W. Coombes; M. C. Delfino; R. de Sangro; W. L. Faissler; E. Fern�ndez; W. T. Ford; M. W. Gettner; G. P. Goderre; Y. Goldschmidt-Clermont; B. Gottschalk; D. E. Groom; B. K. Heltsley; R. B. Hurst; J. R. Johnson; H. S. Kaye; K. H. Lau; T. L. Lavine; H. Y. Lee; R. E. Leedy; S. P. Leung; I. Lippi; E. C. Loh; H. L. Lynch; A. Marini; J. S. Marsh; T. Maruyama; R. L. Messner; O. A. Meyer; S. J. Michalowski; S. Morcos; J. H. Moromisato; R. M. Morse; L. J. Moss; F. Muller; H. N. Nelson; I. Peruzzi; M. Piccolo; R. Prepost; J. Pyrlik; N. Qi; A. L. Read; K. Rich; D. M. Ritson; F. Ronga; L. J. Rosenberg; W. D. Shambroom; J. C. Sleeman; J. G. Smith; J. P. Venuti; P. G. Verdini; E. von Goeler; H. B. Wald; R. Weinstein; D. E. Wiser; R. W. Zdarko
The MAC detector at PEP recorded data for an integrated luminosity of 335 pb-1 between 1980 and 1986. The design of this low-cost MAgnetic Calorimeter was optimized for electron and muon identification, as well as for the measurement of hadronic energy flow. Muon identification is available over 96% of the solid angle, and MAC was the first detector to make
Particle impact location detector
NASA Technical Reports Server (NTRS)
Auer, S. O.
Detector includes delay lines connected to each detector surface strip. When several particles strike different strips simultaneously, pulses generated by each strip are time delayed by certain intervals. Delay time for each strip is known. By observing time delay in pulse, it is possible to locate strip that is struck by particle.
Arsenic activation neutron detector
Jacobs, Eddy L. (Albuquerque, NM)
A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.
Arsenic activation neutron detector
Jacobs, E.L.
A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.
Fabrication and Characterization of Superconducting NbN Nanowire Single Photon Detectors
NASA Technical Reports Server (NTRS)
Stern, Jeffrey A.; Farr, William H.
This viewgraph presentation describes the fabrication of large area superconducting Niobium Nitride nanowire single photon detectors. The topics include: 1) Introduction and Motivation; 2) Operation of SNSPD Detectors; 3) NbTiN Deposition; 4) Fabrication Details; 5) Backside Coupled SNSPD; 6) Measurement Apparatus; 7) Electrical Response of a 15x15 micrometer SNSPD to 1064nm radiation; 8) Detector Efficiency vs Bias Current; 9) Interarrival Time Plot; 10) Detector Linearity; and 11) Conclusion.
Performance of a five-segment coacial n-type germanium detector
NASA Astrophysics Data System (ADS)
Varnell, L. S.; Ling, J. C.; Mahoney, W. A.; Pehl, R. H.; Cork, C. P.; Landis, D. A.; Luke, P. N.; Madden, N. W.; Malone, D. F.
A five-segment n-type coacial detector with associated test cryostat and electronics has been fabricated and tested. Measurements were made of detector efficiency as a function of the number of segments in which interactions occur and the energy threshold of the segment discriminators. The performance of the detector agrees well with predictions. A second detector is now being fabricated along with a rugged mount, flight cryostat, and electronics for use in a future balloon flight.
Advanced far infrared detectors
Haller, E.E.
Recent advances in photoconductive and bolometric semiconductor detectors for wavelength 1 mm > {lambda} > 50 {mu}m are reviewed. Progress in detector performance in this photon energy range has been stimulated by new and stringent requirements for ground based, high altitude and space-borne telescopes for astronomical and astrophysical observations. The paper consists of chapters dealing with the various types of detectors: Be and Ga doped Ge photoconductors, stressed Ge:Ga devices and neutron transmutation doped Ge thermistors. Advances in the understanding of basic detector physics and the introduction of modern semiconductor device technology have led to predictable and reliable fabrication techniques. Integration of detectors into functional arrays has become feasible and is vigorously pursued by groups worldwide.
NASA Technical Reports Server (NTRS)
Fripp, A. L.; Robertson, J. B.; Breckenridge, R. (inventors)
A pyroelectric detector array and the method for using it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strips. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.
NASA Technical Reports Server (NTRS)
Fripp, A. L.; Robertson, J. B.; Breckenridge, R. A. (inventors)
A pryoelectric detector array and the method for making it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strip. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of the layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.
Recent developments in GEM-based neutron detectors
NASA Astrophysics Data System (ADS)
Saenboonruang, K.
The gas electron multiplier (GEM) detector is a relatively new gaseous detector that has been utilized for less than 20 years. Since the discovery in 1997 by F. Sauli, the GEM detector has shown excellent properties including high rate capability, excellent resolution, low discharge probability, and excellent radiation hardness. These promising properties have led the GEM detector to gain popularity and attention amongst physicists and researchers. In particular, the GEM detector can also be modified to be used as a neutron detector by adding appropriate neutron converters. With properties stated above and the need to replace the previous expensive 3He-based neutron detectors, the GEM-based neutron detector could be one of the most powerful and affordable neutron detectors. Applications of the GEM-based neutron detectors vary from researches in nuclear and particle physics, neutron imaging, and national security. Although several promising progresses and results have been shown and published in the past few years, further improvement is still needed in order to improve the low neutron detection efficiency (only a few percent) and to widen the possibilities for other uses.
Normable metrological characteristics of groups of seismic detectors
Manokhin, A.E.
An analysis is made of metrological characteristics of seismic detectors categorized in different groups. A discussion is presented of aspects of calculating the characteristics of a group from the parameters of individual detectors while using different methods to compare these parameters. The method of reflected waves is widely used in modern seismic prospecting. Prospecting is made more efficient by using groups of seismic detectors connected in parallel, in series, or in a combination scheme. Seismic detectors may be joined into groups either in the field or during production at the factory. In either case, it is necessary to evaluate the quality of the group as a single product. Such evaluation in turn requires an adequate set of representative parameters. This problem has yet to be fully resolved and remains an important issue. The advantages of grouping seismic detectors includes strengthening of the useful signal achieved as a result of the directionality of the detectors sensitivity, frequency filtration and averaging of discontinuities connected with the arrangement of the detectors, and relative attenuation of random noise. Signal strength depends on the distance between the detectors in the given group, the number and arrangement of the detectors, the length of the wave being recorded, and the characteristics of the detectors joined to form the group (conversion factor, damping factor, natural frequency, etc.)
Beam Test of a Large Area nonn Silicon Strip Detector with Fast Binary Readout Electronics
Beam Test of a Large Area n�on�n Silicon Strip Detector with Fast Binary Readout Electronics Y test was carried out for the non�irradiated and the irradiated detector modules. Efficiency, noise occupancy and performance in the edge regions were analyzed using the beam test data. High efficiency
Using standard calibrated geometries to characterize a coaxial high purity germanium gamma detector for Monte Carlo simulations
Graaf, E. R. van der, E-mail: firstname.lastname@example.com; Dendooven, P.; Brandenburg, S. [KVI-Center for Advanced Radiation Technology (KVI-CART), University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands)
A detector model optimization procedure based on matching Monte Carlo simulations with measurements for two experimentally calibrated sample geometries which are frequently used in radioactivity measurement laboratories results in relative agreement within 5% between simulated and measured efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.
Arc detector uses fiber optics
NASA Technical Reports Server (NTRS)
Finnegan, E. J.; Leech, R. A.
Arc detector for protecting high-power microwave klystron oscillators uses fiber optics connected to remote solid-state light-sensing circuits. Detector is more reliable, smaller, and sensitive than other systems that locate detector in waveguide.
Application of the Monte Carlo method for the calibration of an in situ gamma spectrometer.
Tzika, Faidra; Kontogeorgakos, Dimitrios; Vasilopoulou, Theodora; Stamatelatos, Ion E
A MCNP model was developed for the efficiency calibration of an in situ gamma ray spectrometry system based on a high purity germanium (HPGe) detector. The detector active crystal volume was adjusted semi-empirically against experimental measurements. Calculated full energy peak efficiency curves, over the photon energy range between 50 keV and 5 MeV, are presented for surface and slab source configurations. The effect of different collimator apertures and the contribution of different HPGe crystal regions in the detector response are also shown. PMID:19945289
Production of the Alpha-Particle Emitting Radionuclide Astatine-211 at the Texas A&M Cyclotron Institute�
Bhakta, Viharkumar Satish
connections. 6) Vacuum system. ................................................................................... 27 Figure 10 Background spectrum obtained using HPGe detector in the counting room. The only major gamma contribution observed... was that of potassium-40 (K-40) at 1.460 MeV ........................................ 30 Figure 11 Uncalibrated Co-60 spectrum at 10 cm (Counts v. Channel Number) ..... 32 Figure 12 HPGe efficiency curves utilized for gamma-ray spectroscopy at different source...
The Particle-Gamma Detector GODDESS
NASA Astrophysics Data System (ADS)
Ratkiewicz, A.; Cizewski, J. A.; Baugher, T.; Burcher, S.; Hardy, S.; Lonsdale, S.; Shand, C.; Pain, S. D.; Marsh, I.; Jones, K. L.; Peters, W. A.; Carpenter, M. P.; Seweryniak, D.; Zhu, S.; Kozub, R. L.; Afanasieva, L.; Blackmon, J. C.
Transfer reactions in inverse kinematics provide a powerful probe of the single-particle structure of nuclei far from stability. The Californium Rare Isotope Breeder (CARIBU) at ATLAS produces exotic nuclei near possible r-process paths and makes them available for study. Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) employs the large internal geometry of the high-resolution ?-ray detector Gammasphere to instrument the large-area position-sensitive particle detector ORRUBA. This coupling of Gammasphere and ORRUBA allows high-efficiency, high-resolution measurements of surrogate reactions for neutron capture, collective excitations via inelastic scattering, pickup reactions (such as (d,t)), and stripping reactions (e.g. (d,p)). Results from commissioning measurements and plans for future experiments will be presented. This work is supported in part by the U.S. Department of Energy and the National Science Foundation.
Extrinsic germanium Blocked Impurity Bank (BIB) detectors
NASA Technical Reports Server (NTRS)
Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.
Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.
Development of a Neutron Detector for A1 at MAMI
NASA Astrophysics Data System (ADS)
Pierce, Zoe
The Mainz A1 spectrometers perform high precision measurements to investigate the structure of the nucleus and its constituents. Previous knowledge of the neutron form factor (FF) is limited due to poor detection efficiencies. Our goal is to create a neutron detector with an efficiency better than 80%, leading to the improvement of the measurements of the neutron electric FF and reducing systematic uncertainties. This new detector would also open up the possibility to study non-mesonic two-body weak decays. The neutron detector should have a large active detector volume, a high detection efficiency (>80%), a good resolution (<.5 ns), and must be low in cost. The proposed design of the detector follows a modular concept with an active detector volume of approximately one cubic meter. In order to allow high beam currents and their resulting high rates, this detector will be highly segmented using 32 crossed layers consisting of 64 bars, utilizing solid and liquid organic scintillators, with dimensions (15 x 30 x 960) mm3. In total 4096 channels have to be read out via WLS fibers using silicon multi pixel photon counters (MPPC). Funded by NSF IRES Award IIA-1358175 Collaboration: MAMI A1 Collaboration.
NASA Astrophysics Data System (ADS)
Morris, Matthew J.; Kaiser, M.; Rauscher, B. J.; Kimble, R. A.; Kruk, J. W.; Mott, D. B.; Wen, Y.; Foltz, R.; McCandliss, S. R.; Pelton, R. S.; Wright, E. L.; Feldman, P. D.; Moos, H. W.; Riess, A. G.; Benford, D. J.; Gardner, J. P.; Woodgate, B. E.; Bohlin, R.; Deustua, S. E.; Dixon, W. V.; Sahnow, D. J.; Kurucz, R. L.; Lampton, M.; Perlmutter, S.
ACCESS, Absolute Color Calibration Experiment for Standard Stars, is a series of rocket-borne sub-orbital missions and ground-based experiments that will enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 to 1.7 micron bandpass (overview Kaiser et al.). The flight detector and detector spare have been integrated with their electronics and flight mount. The controller electronics have been flight qualified. Vibration testing to launch loads and thermal vacuum testing of the detector, mount, and housing have been performed. The flight detector controller boards have been installed into a ruggedized flight housing. They have been successfully vacuum tested for periods significantly longer than the flight length, and components have been heat-sunk and reinforced as necessary. Thermal stability tests have been performed, and results will be presented. Goddard Space Flight Center�s Detector Characterization Lab (DCL) executed initial characterization tests for the flight detector in 2007. These were repeated in 2012, to ensure and establish baseline performance. Current lab characterization tests at Johns Hopkins are ongoing, and results will be presented. NASA sounding rocket grant NNX08AI65G supports this work.
Detectors for Tomorrow's Instruments
NASA Technical Reports Server (NTRS)
Moseley, Harvey
Cryogenically cooled superconducting detectors have become essential tools for a wide range of measurement applications, ranging from quantum limited heterodyne detection in the millimeter range to direct searches for dark matter with superconducting phonon detectors operating at 20 mK. Superconducting detectors have several fundamental and practical advantages which have resulted in their rapid adoption by experimenters. Their excellent performance arises in part from reductions in noise resulting from their low operating temperatures, but unique superconducting properties provide a wide range of mechanisms for detection. For example, the steep dependence of resistance with temperature on the superconductor/normal transition provides a sensitive thermometer for calorimetric and bolometric applications. Parametric changes in the properties of superconducting resonators provides a mechanism for high sensitivity detection of submillimeter photons. From a practical point of view, the use of superconducting detectors has grown rapidly because many of these devices couple well to SQUID amplifiers, which are easily integrated with the detectors. These SQUID-based amplifiers and multiplexers have matured with the detectors; they are convenient to use, and have excellent noise performance. The first generation of fully integrated large scale superconducting detection systems are now being deployed. I will discuss the prospects for a new generation of instruments designed to take full advantage of the revolution in detector technology.
Advanced Gravitational Wave Detectors
NASA Astrophysics Data System (ADS)
Blair, D. G.; Howell, E. J.; Ju, L.; Zhao, C.
Part I. An Introduction to Gravitational Wave Astronomy and Detectors: 1. Gravitational waves D. G. Blair, L. Ju, C. Zhao and E. J. Howell; 2. Sources of gravitational waves D. G. Blair and E. J. Howell; 3. Gravitational wave detectors D. G. Blair, L. Ju, C. Zhao, H. Miao, E. J. Howell, and P. Barriga; 4. Gravitational wave data analysis B. S. Sathyaprakash and B. F. Schutz; 5. Network analysis L. Wen and B. F. Schutz; Part II. Current Laser Interferometer Detectors: Three Case Studies: 6. The Laser Interferometer Gravitational-Wave Observatory P. Fritschel; 7. The VIRGO detector S. Braccini; 8. GEO 600 H. L�ck and H. Grote; Part III. Technology for Advanced Gravitational Wave Detectors: 9. Lasers for high optical power interferometers B. Willke and M. Frede; 10. Thermal noise, suspensions and test masses L. Ju, G. Harry and B. Lee; 11. Vibration isolation: Part 1. Seismic isolation for advanced LIGO B. Lantz; Part 2. Passive isolation J-C. Dumas; 12. Interferometer sensing and control P. Barriga; 13. Stabilizing interferometers against high optical power effects C. Zhao, L. Ju, S. Gras and D. G. Blair; Part IV. Technology for Third Generation Gravitational Wave Detectors: 14. Cryogenic interferometers J. Degallaix; 15. Quantum theory of laser-interferometer GW detectors H. Miao and Y. Chen; 16. ET. A third generation observatory M. Punturo and H. L�ck; Index.
Efficient single particle detection with a superconducting nanowire
NASA Astrophysics Data System (ADS)
Azzouz, Hatim; Dorenbos, Sander N.; De Vries, Daniel; Ure�a, Esteban Berm�dez; Zwiller, Valery
Detection of ?- and ?-particles is of paramount importance in a wide range of applications. Current particle detectors are all macroscopic and have limited time resolution. We demonstrate a nanoscale particle detector with a small detection volume, high detection efficiency, short dead times and low dark count levels. We measure ?- and ?-particle detection efficiencies close to unity using different sources and also demonstrate blindness towards ?-rays. Our nanoscale detector offers particle detection measurements with unprecendented spatial resolution.
Dan Green
The LHC detectors are well into their construction phase. The LHC schedule shows first beam to ATLAS and CMS in 2007. Because the LHC accelerator has begun to plan for a ten fold increase in LHC design luminosity (the SLHC or super LHC) it is none too soon to begin to think about the upgrades which will be required of the present LHC detectors. In particular, the tracking systems of ATLAS and CMS will need to be completely rebuilt. Given the time needed to do the R & D, make prototypes, and construct the new detectors and given the accelerator schedule for the SLHC, work needs to begin rather soon.
A comparison of 137 Cs radioactivity in localized evergreen and deciduous plant species
Rangel, Ruben Canales
3. 2 km (2 mi) ofCPSES. . . . . . . 40 12. CPSES Off-site TAMU Control Sample Station (*) . . . . . . . . . . . . . 41 13. Energy Calibration Curve for HPGe Detector No. 1. . . . . . . . . . . . . . . 91 14. Energy Calibration Curve for HPGe.... . . . . 107 29. TAMU SCP BL-1 Spectral Data for HPGe Detector No. 2. . . . . 109 30. TAMU PP J-2 Spectral Data for HPGe Detector No. 2. . . . . . . . 110 31. TAMU PP BL-2 Spectral Data for HPGe Detector No. 2 . . . . 111 32. TAMU PP J-3 Spectral Data...
The ATLAS Inner Detector commissioning and calibration
Aad, Georges; Abdallah, Jalal; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; Abramowicz, Halina; Abreu, Henso; Acharya, Bobby Samir; Adams, David; Addy, Tetteh; Adelman, Jahred; Adorisio, Cristina; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; �kesson, Torsten Paul Ake; Akimoto, Ginga; Akimov , Andrei; Aktas, Adil; Alam, Mohammad; Alam, Muhammad Aftab; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Aliyev, Magsud; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alviggi, Mariagrazia; Amako, Katsuya; Amelung, Christoph; Amorim, Antonio; Amor�s, Gabriel; Amram, Nir; Anastopoulos, Christos; Andeen, Timothy; Anders, Christoph Falk; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Anduaga, Xabier; Angerami, Aaron; Anghinolfi, Francis; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonelli, Stefano; Antos, Jaroslav; Antunovic, Bijana; Anulli, Fabio; Aoun, Sahar; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Archambault, John-Paul; Arfaoui, Samir; Arguin, Jean-Francois; Argyropoulos, Theodoros; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnault, Christian; Artamonov, Andrei; Arutinov, David; Asai, Makoto; Asai, Shoji; Silva, Jos�; Asfandiyarov, Ruslan; Ask, Stefan; �sman, Barbro; Asner, David; Asquith, Lily; Assamagan, Ketevi; Astvatsatourov, Anatoli; Atoian, Grigor; Auerbach, Benjamin; Augsten, Kamil; Aurousseau, Mathieu; Austin, Nicholas; Avolio, Giuseppe; Avramidou, Rachel Maria; Ay, Cano; Azuelos, Georges; Azuma, Yuya; Baak, Max; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Badescu, Elisabeta; Bagnaia, Paolo; Bai, Yu; Bain, Travis; Baines, John; Baker, Mark; Baker, Oliver Keith; Baker, Sarah; Baltasar Dos Santos Pedrosa, Fernando; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Baranov, Sergei; Barashkou, Andrei; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barr, Alan; Barreiro, Fernando; Barreiro Guimar�es da Costa, Jo�o; Barrillon, Pierre; Bartoldus, Rainer; Bartsch, Detlef; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Bazalova, Magdalena; Beare, Brian; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Graham; Beck, Hans Peter; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Ayda; Beddall, Andrew; Bednyakov, Vadim; Bee, Christopher; Begel, Michael; Behar Harpaz, Silvia; Behera, Prafulla; Beimforde, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellina, Francesco; Bellomo, Massimiliano; Belloni, Alberto; Belotskiy, Konstantin; Beltramello, Olga; Ben Ami, Sagi; Benary, Odette; Benchekroun, Driss; Bendel, Markus; Benedict, Brian Hugues; Benekos, Nektarios; Benhammou, Yan; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Beretta, Matteo; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, J�rg; Bernab�u , Jos�; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Berry, Tracey; Bertin, Antonio; Besana, Maria Ilaria; Besson, Nathalie; Bethke, Siegfried; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bitenc, Urban; Black, Kevin; Blair, Robert; Blanchard, Jean-Baptiste; Blanchot, Georges; Blocker, Craig; Blondel, Alain; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bocci, Andrea; Boehler, Michael; Boek, Jennifer; Boelaert, Nele; B�ser, Sebastian; Bogaerts, Joannes Andreas; Bogouch, Andrei; Bohm, Christian; Bohm, Jan; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Bondarenko, Valery; Bondioli, Mario; Boonekamp, Maarten; Bordoni, Stefania; Borer, Claudia; Borisov, Anatoly; Borissov, Guennadi; Borjanovic, Iris; Borroni, Sara; Bos, Kors; Boscherini, Davide; Bosman, Martine; Boterenbrood, Hendrik; Bouchami, Jihene; Boudreau, Joseph
The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data- taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1+/-0.9 {\\mu}m and a relative momentum resolution {\\sigma}p/p = (4.83+/-0.16)...
Measurement of terrestrial gamma radiation dose-rate (TGRD) level in soil samples from the district of Rembau, Malaysia, using high-purity Germanium detectors
NASA Astrophysics Data System (ADS)
Norbani, N. E.; Abdullah Salim, N. A.; Rahman, A. T. Abdul
This study assesses the gamma radiation levels and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected from the district of Rembau, Malaysia using High-purity Germanium (HPGe) Detectors. A 105 measurement were performed on surface soil using NaI (Tl) gamma-ray detector with crystal size 1"x1", covering about 83% land of the Rembau district. The concentration of the naturally occurring radionuclides 232Th, 238U and 40K in soil samples collected were determined by using HPGe detector based on high-resolution gamma spectrometry system at Malaysia Nuclear Agency. The range of natural gamma radiation measured was from 114�14 nGy h?1 to 857�14 nGy h?1. The range of activity concentrations of U, Th and �K in soil from the studied areas varies from 151-401 Bq kg?1, 113-342 Bq kg?1 and 674-1526 Bq kg?1 with mean values of 245 Bq kg?1, 186 Bq kg?1 and 1152 Bq kg1 respectively. The mean values of terrestrial gamma radiation dose rate measured in Rembau district is 383�18 nGy h?1 compared to the Malaysian average is 92 nGy h?1 and world average is 59 nGy h?1 (UNSCEAR, 2000). The average annual dose from such terrestrial gamma radiation dose rates to an individual in Rembau district, assuming a tropical rural setting is estimated to be 0.78 mSv per year, which is considered to be within the normal range for doses from natural sources. An isodose map for the Rembau district has been plotted.
The HERMES Recoil Detector Recoil Detector Test Beams
detector versus the of the incoming particle and the position of incidence on the strip. The data was takenThe HERMES Recoil Detector Recoil Detector Test Beams A will be installed to the HERMES experiment of fromprotons recoil detector Deeply Virtual Compton Scattering (DVCS). Recoil proton momentum versus polar
The DEAP 3600 Dark Mater Detector
NASA Astrophysics Data System (ADS)
Sonley, Thomas; DEAP-3600 Collaboration
The DEAP-3600 dark matter detector consists of 3,600 kg of liquid argon contained in an ultra-pure acrylic cryogenic vessel. The experiment is located 2 km underground at SNOLAB. DEAP-3600 is entering the commissioning phase. Scintillation light from events in the detector is observed by 255 high-efficiency room temperature PMTs. Electromagnetic backgrounds, including those from argon-39, are rejected using pulse shape discrimination based on timing. Backgrounds from neutrons and alphas are mitigated by ensuring excellent radiopurity and using a high efficiency neutron shield. The DEAP-3600 background budget is 0.2 events per year allowing a cross-section sensitivity of 10-46 cm2 for scattering of Weakly Interacting Massive Particles with a 100-GeV mass in a 3-year run. In this talk, we will describe the status and physics reach, highlighting that it is expected to reach competitive sensitivity within months of the start of data collection.