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The Extended Q-Range Small Angle Neutron Scattering ...
Science Conference Proceedings (OSTI)
Abstract Scope, The Extended Q-Range Small Angle Neutron Scattering Diffractometer (EQ-SANS) at the Spallation Neutron Source (SNS) is a high intensity�...
Industrial Applications at Small Angle Neutron Scattering and ...
... at Small Angle Neutron Scattering and Neutron Diffraction of HANARO Reactor .... Structure/Microstructure Analysis of Faulted and Modular Materials from�...
USANS: the Ultra-Small-Angle Neutron Scattering Instrument at...
NLE Websites -- All DOE Office Websites (Extended Search)
USANS-Ultra-Small-Angle Neutron Scattering Instrument USANS is designed for the study of hierarchical structures in natural and artificial materials. It can be considered an...
Characterization of photosynthetic supramolecular assemblies using small angle neutron scattering
DOE Green Energy (OSTI)
We are using small angle neutron scattering (SANS) to resolve structural features of supramolecular assemblies of photosynthetic proteins in liquid and frozen solutions. SANS resolves the size, shape, and structural homogeneity of macromolecular assemblies in samples identical to those used for spectroscopic assays of photosynthetic function. Likely molecular structures of the supramolecular assemblies can be identified by comparing experimental scattering data with scattering profiles calculated for model supramolecular assemblies built from crystal structures of the individual proteins. SANS studies of the Rhodobacter sphaeroides reaction center, RC, presented here, show that the detergent solubilized RC exists in a variety of monomeric and aggregation states. The distribution between monomer and aggregate was found to depend strongly upon detergent, temperature and nature of additives, such as ethylene glycol used for low temperature spectroscopy and polyethylene glycol used for crystallization. Likely aggregate structures are being identified by fitting the experimental scattering profiles with those calculated for model aggregates built-up using the RC crystal structure. This work establishes the foundation for using SANS to identify intermediates in the RC crystallization pathways, and for determining likely structures of complexes formed between the RC and its physiological reaction partners, cytochrome c, and the LHI antenna complex.
Tiede, D.M.; Marone, P.; Wagner, A.M.; Thiyagarajan, P.
Introduction to Small-Angle Neutron Scattering and Neutron ...
... where g(r) is the pair correlation function for the scattering objects and lng(r) is directly related to the potential energy function that describes the ...
Bio-SANS: the Biological Small-Angle Neutron Scattering Instrument...
Biological Small-Angle Neutron Scattering Instrument at HFIR Detector tanks for the new SANS instruments at HFIR. The Bio-SANS detector is on the right. Detector tanks for the SANS...
EQ-SANS: the Extended Q-Range Small-Angle Neutron Scattering Diffractometer
The Extended Q-Range Small-Angle Neutron Scattering Diffractometer at SNS The Extended Q-Range Small-Angle Neutron Scattering Diffractometer at SNS Extended Q-Range Small Angle Diffractometer EQ-SANS detector array The EQ-SANS Diffractometer is designed to study non-crystalline, nano-sized materials in solid, liquid, or gas forms such as polymers, micelles, proteins, and other large biological molecular complexes in solution. It offers high neutron flux, high wavelength resolution (precision), and wide Q-coverage. EQSANS is located on beam line 6, viewing the top-downstream, coupled supercritical hydrogen moderator. It has a curved multichannel beam bender to avoid the direct line of sight of the moderator, which cleans out the background from the prompt neutron pulse quite effectively. The cutoff wavelength of the optics is ~1.5 Å. Above this minimum wavelength, the
Small-Angle Neutron Scattering Studies of a-Si:H and a-Si:D
The heterogeneity of hydrogen and deuterium on the nanometer scale has been probed by samll-angle neutron scattering (SANS) from a-Si:H and a-Si:D films. Films were depsoited by two techniques, plasma-enhanced chemical vapor deposition (PECVD) and hot-wire chemical vapor deposition (HWCVD) using conditions that yield high quality films and devices.
Williamson, D. L.; Marr, D. W. M.; Nelson, B. P.; Iwaniczko, E.; Yang, J.; Yan, B.; Guha, S.
The General-Purpose Small-Angle Neutron Scattering Diffractometer at HFIR -
General-Purpose Small-Angle Neutron Scattering Diffractometer at HFIR General-Purpose Small-Angle Neutron Scattering Diffractometer at HFIR Instrument scientist Ken Littrell at GP-SANS. Instrument scientist Ken Littrell at GP-SANS. The General-Purpose Small-Angle Neutron Scattering Diffractometer (GP-SANS) instrument is optimized for providing information about structure and interactions in materials in the size range of 0.5 - 200 nm. It has a cold neutron flux on sample and capabilities comparable to those of the best SANS instruments worldwide, including a wide range of neutron wavelengths λ 5 - 30 Å, resolution Δλ ⁄ λ 9=45%, and a 1m2 area detector with 5 × 5mm2 pixel resolution with a maximum counting capability of up to 2.5 kHz. The sample-to-detector distance can be varied from 1 to 20 m, and the detector can be offset horizontally by up to 45 cm, allowing
Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.
Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. Results from this study, combined with high-resolution TEM imaging, provide insight into the differences in volume and geometry of porosity between these various mudstones.
McCray, John (Colorado School of Mines); Navarre-Sitchler, Alexis (Colorado School of Mines); Mouzakis, Katherine (Colorado School of Mines); Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot (Oak Ridge National Laboratory)
Use of Small Angle Neutron Scattering to Study Various Properties of Wool and Mohair Fibres
SciTech Connect
To maintain a competitive edge in the wool and mohair industry, a detailed knowledge and understanding of the properties of wool fibres is essential. Standard techniques are used to determine fibre diameter, length and strength; however, properties such as hydroscopicity, lustre and changes in fibre structure following chemical or mechanical treatment are not so well understood. The unique capabilities of small angle neutron scattering to study changes in the supermolecular structure of wool fibres, particularly at the level of the microfibril-matrix complex, have been used to provide previously unknown features of the fibres. The results of these studies are presented.
Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa); Toeroek, Gy. [Research Institute for Solid State Physics and Optics, H-1525 Budapest, POB 49 (Hungary)
Small angle neutron scattering analysis of novel carbons for lithium secondary batteries.
Small angle neutron scattering analyses of carbonaceous materials used as anodes in lithium ion cells have been performed. The carbons have been synthesized using pillared clays (PILCs) as inorganic templates. Pillared clays are layered silicates whose sheets have been permanently propped open by sets of thermally stable molecular props. The calcined PILC was loaded with five different organic precursors and heated at 700 C under nitrogen. When the inorganic pillars were removed by acid treatment, carbon sheets are produced with holes. The fitting of the data in the high q region suggested that the carbon sheets have voids with radii ranging from 4 to 8 {angstrom}. Similar radii were obtained for the PILC and PILC/organic precursor, which suggests that the carbon was well distributed in the clay prior to pyrolysis.
Sandi, G.; Thiyagarajan, P.; Winans, R.; Carrado, K.
Soluble Hydrogen-bonding Interpolymer Complexes in Water: A Small-Angle Neutron Scattering Study
E-Print Network (OSTI)
The hydrogen-bonding interpolymer complexation between poly(acrylic acid) (PAA) and the poly(N,N-dimethylacrylamide) (PDMAM) side chains of the negatively charged graft copolymer poly(acrylic acid-co-2-acrylamido-2-methyl-1-propane sulfonic acid)-graft-poly(N, N dimethylacrylamide) (P(AA-co-AMPSA)-g-PDMAM), containing 48 wt % of PDMAM, and shortly designated as G48, has been studied by small-angle neutron scattering in aqueous solution. Complexation occurs at low pH (pH hydrogen-bonding interpolymer complexes, whose radius is estimated to be around 165 A. As these particles involve more than five graft copolymer chains, they act as stickers between the anionic chains of the graft copolymer backbone. This can explain the characteristic thickening observed in past rheological measurements with these mixtures in the semidilute solution, with decreasing pH. We have also examined the influence of pH and PAA molecular weight on the formation of these nanoparticles.
Maria Sotiropoulou; Julian Oberdisse; Georgios Staikos
Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science, ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.
Imaging with Scattered Neutrons
We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-resolution images by scattered neutron radiography and tomography are presented.
H. Ballhausen; H. Abele; R. Gaehler; M. Trapp; A. Van Overberghe
The 30 m Small-Angle Neutron Scattering Instruments at the ...
... The 30 m SANS instrument on neutron guide NG-7, in operation since May 1991, was developed jointly by NIST, the Exxon Research and ...
In-Situ Observation of Solid Electrolyte Interphase Formation in Ordered Mesoporous Hard Carbon by Small-Angle Neutron Scattering
The aim of this work was to better understand the electrochemical processes occurring during the cycling of a lithium-ion half-cell containing ordered mesoporous hard carbon using time-resolved in situ small-angle neutron scattering (SANS). Utilizing electrolytes containing mixtures of deuterated (2H) and non-deuterated (1H) carbonates, we have addressed the challenging task of monitoring the formation and evolution of the solid-electrolyte interphase (SEI) layer. An evolution occurs in the SEI layer during discharge from a composition dominated by a higher scattering length density (SLD) lithium salt, to a lower SLD lithium salt for the ethylene carbonate/dimethyl carbonate (EC/DMC) mixture employed. By comparing half-cells containing different solvent deuteration levels, we show that it is possible to observe both SEI formation and lithium intercalation occurring concurrently at the low voltage region in which lithium intercalates into the hard carbon. These results demonstrate that SANS can be employed to monitor complicated electrochemical processes occurring in rechargeable batteries, in a manner that simultaneously provides information on the composition and microstructure of the electrode.
Bridges, Craig A [ORNL; Paranthaman, Mariappan Parans [ORNL; Sun, Xiao-Guang [ORNL; Zhao, Jinkui [ORNL; Dai, Sheng [ORNL
Neutron Scattering Facilities 1982
NEUTRON SOURCES NEUTRON SOURCES Types of Sources U.S. Sources Available for Users Plans for the Future The Neutron Scattering Society of America (NSSA) SNS/ANL School on Neutron and x-Ray Scattering, June 2011 Jim Rhyne Lujan Neutron Scattering Center Los Alamos National Lab. What do we need to do neutron scattering? * Neutron Source - produces neutrons * Diffractometer or Spectrometer - Allows neutrons to interact with sample - Sorts out discrete wavelengths by monochromator (reactor) or by time of flight (pulse source) - Detectors pick up neutrons scattered from sample * Analysis methods to determine material properties * Brain power to interpret results Sources of neutrons for scattering * Nuclear Reactor - Neutrons produced from fission of 235 U - Fission spectrum neutrons
Growth Kinetics of Lipid-Based Nanodiscs to Unilamellar Vesicles: A Time-Resolved Small Angle Neutron Scattering (SANS) Study
Mixtures of dimyristoyl-phosphatidylcholine (DMPC), dimyristoyl-phosphatidylglycerol (DMPG) and dihexanoylphosphatidylcholine (DHPC) in aqueous solutions spontaneously form monodisperse, bilayered nanodiscs (also known as bicelles ) at or below the melting transition temperature of DMPC (TM ~23 C). In dilute systems above the main transition temperature TM of DMPC, bicelles coalesce (increasing their diameter) and eventually self-fold into unilamellar vesicles (ULVs). Time resolved small angle neutron scattering was used to study the growth kinetics of nanodiscs below and equal to TM over a period of hours as a function of temperature at two lipid concentrations in presence or absence of NaCl salt. Bicelles seem to undergo a sudden initial growth phase with increased temperature, which is then followed by a slower reaction-limited growth phase that depends on ionic strength, lipid concentration and temperature. The bicelle interaction energy was derived from the colloidal theory of Derjaguin and Landau, and Verwey and Overbeek (DLVO). While the calculated total energy between discs is attractive and proportional to their growth rate, a more detailed mechanism is proposed to describe the mechanism of disc coalescence. After annealing at low temperature (low-T), samples were heated to 50 C in order to promote the formation of ULVs. Although the low-T annealing of samples has only a marginal effect on the mean size of end-state ULVs, it does affect their polydispersity, which increases with increased T, presumably driven by the entropy of the system.
Mahabir, Suanne [University of Western Ontario, The; Small, Darcy [University of Western Ontario, The; Li, Ming [University of Connecticut, Storrs; Wan, Wankei [University of Western Ontario, The; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Littrell, Ken [ORNL; Katsaras, John [ORNL; Nieh, Mu-Ping [University of Connecticut, Storrs
Physics @ Oxford SCATTERING NEUTRONS
1 Neutron Scattering Society of America (NSSA) Purpose and New Initiatives www.neutronscattering.org SNS/ANL School on Neutron and X-Ray Scattering June 2011 Visit us now on Facebook #12;2 What is the NSSA? NSSA is an organization of scientists and engineers with a common interest in using neutron
Herz, Laura M.
Anomalous and resonance small angle scattering
Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same or the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small-angle neutron scatterings are discussed. 8 figs.
Epperson, J.E.; Thiyagarajan, P.
Anomalous and resonance small angle scattering: Revision
Significant changes in the small angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous dispersion terms for the scattering factor (x-rays) or scattering length (neutrons). The physics inherent in these anomalous dispersion terms is first discussed before considering how they enter the relevant scattering theory. Two major areas of anomalous scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with x-rays. However, it is pointed out that the formalism is the same for the analogue experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small angle neutron scatterings are discussed. 54 refs., 8 figs., 1 tab.
A small angle neutron scattering investigation of the kinetics of phase separation in an Fe-27. 5 at. % Cr-5. 6 at. % Ni alloy
The small angle neutron scattering has been investigated in situ at 450{degree} and 500{degree}C for a polycrystalline, duplex Fe-27.5 at. % Cr-5.6 at. % Ni steel. A broad diffuse maximum in the scattering function is the signature of the {alpha}{prime}-phase formation, and this maximum is superimposed on a strong, temperature-dependent component due to critical magnetic scattering. The time dependence of the shift in the peak intensity position to lower scattering vectors and the increase in peak intensity obey power law scaling behavior. Furthermore, the structure function exhibits dynamical scaling, after about three hours annealing. It is suggested that this behavior could be utilized to predict the microstructure, and hence some of the properties, after significantly longer annealing times. 21 refs., 3 figs.
Epperson, J.E. (Argonne National Lab., IL (USA)); Rainey, V.S.; Windsor, C.G. (UKAEA Atomic Energy Research Establishment, Harwell (UK). Materials Physics and Metallurgy Div.); Hawick, K.A. (Edinburgh Univ. (UK). Dept. of Physics); Chen, H. (Illinois Univ., Urbana, IL (USA). Dept. of Materials Science and Engineering)
Digenetic Changes in Macro- to Nano-Scale Porosity in the St. Peter Sandstone:L An (Ultra) Small Angle Neutron Scattering and Backscattered Electron Imagining Analysis
Small- and Ultra-Small Angle Neutron Scattering (SANS and USANS) provide powerful tools for quantitative analysis of porous rocks, yielding bulk statistical information over a wide range of length scales. This study utilized (U)SANS to characterize shallowly buried quartz arenites from the St. Peter Sandstone. Backscattered electron imaging was also used to extend the data to larger scales. These samples contain significant volumes of large-scale porosity, modified by quartz overgrowths, and neutron scattering results show significant sub-micron porosity. While previous scattering data from sandstones suggest scattering is dominated by surface fractal behavior over many orders of magnitude, careful analysis of our data shows both fractal and pseudo-fractal behavior. The scattering curves are composed of subtle steps, modeled as polydispersed assemblages of pores with log-normal distributions. However, in some samples an additional surface-fractal overprint is present, while in others there is no such structure, and scattering can be explained by summation of non-fractal structures. Combined with our work on other rock-types, these data suggest that microporosity is more prevalent, and may play a much more important role than previously thought in fluid/rock interactions.
Anovitz, Lawrence {Larry} M [ORNL; Cole, David [Ohio State University; Rother, Gernot [ORNL; Allard Jr, Lawrence Frederick [ORNL; Jackson, Andrew [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Littrell, Ken [ORNL
Neutron Scattering Web
at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site. We will leave the current content here for...
Neutron Scattering Template
Acknowledgements The graphics used on the Neutron Scattering Web Pages were designed by Tami Sharley (Information and Publishing Services Division) and Jack Carpenter (Intense...
Neutron Scattering Software
Software Software A new portal for neutron scattering has just been established at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site. We will leave the current content here for archival purposes but no new content will be added. We encourage everyone interested in neutron scattering to take full advantage of this exciting new resource for our community. Neutronsources.org Data Formats NeXus: Neutron and X-ray Data Format Crystallographic Binary Format (CBF/imgCIF) Hierarchical Data Format (HDF) Data Analysis and Visualization Data Analysis for Neutron Scattering Experiments (DANSE): distributed data analysis project Large Array Manipulation Program (LAMP): IDL-based data analysis and visualization
Structural hierarchy of chromatin in chicken erythrocyte nuclei based on small-angle neutron scattering: Fractal nature of the large-scale chromatin organization
The chromatin organization in chicken erythrocyte nuclei was studied by small-angle neutron scattering in the scattering-vector range from 1.5 x 10{sup -1} to 10{sup -4} A{sup -1} with the use of the contrast-variation technique. This scattering-vector range corresponds to linear dimensions from 4 nm to 6 {mu}m and covers the whole hierarchy of chromatin structures, from the nucleosomal structure to the entire nucleus. The results of the present study allowed the following conclusions to be drawn: (1) both the chromatin-protein structure and the structure of the nucleic acid component in chicken erythrocyte nuclei have mass-fractal properties, (2) the structure of the protein component of chromatin exhibits a fractal behavior on scales extending over two orders of magnitude, from the nucleosomal size to the size of an entire nucleus, and (3) the structure of the nucleic acid component of chromatin in chicken erythrocyte nuclei is likewise of a fractal nature and has two levels of organization or two phases with the crossover point at about 300-400 nm.
Lebedev, D. V., E-mail: firstname.lastname@example.com; Filatov, M. V. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation); Kuklin, A. I.; Islamov, A. Kh. [Joint Institute of Nuclear Research (Russian Federation); Stellbrink, J. [Research Centre Juelich (Germany); Pantina, R. A.; Denisov, Yu. Yu.; Toperverg, B. P.; Isaev-Ivanov, V. V. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation)
Neutron Scattering Conference Archive
Conference Archive Conference Archive A new portal for neutron scattering has just been established at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site. We will leave the current content here for archival purposes but no new content will be added. We encourage everyone interested in neutron scattering to take full advantage of this exciting new resource for our community. Neutronsources.org 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 2000 June 12-14, 2000 Workshop on "New Opportunities for Better User Group Software (NOBUGS III)" Location Daresbury Laboratory, Cheshire, UK Contact Mark Enderby, Daresbury Laboratory Email firstname.lastname@example.com URL http://nobugs.dl.ac.uk/
Diffusion and adsorption of methane confined in nanoporous carbon aerogel: a combined quasi-elastic and small-angle neutron scattering study
The diffusion of methane confined in nano-porous carbon aerogel with the average pore size 48 {angstrom} and porosity 60% was investigated as a function of pressure at T = 298 K using quasi-elastic neutron scattering (QENS). The diffusivity of methane shows a clear effect of confinement: it is about two orders of magnitude lower than in bulk at the same thermodynamic conditions and is close to the diffusivity of liquid methane at 100 K (i.e. {approx} 90 K below the liquid-gas critical temperature T{sub C} {approx} 191 K). The diffusion coefficient (D) of methane initially increases with pressure by a factor of {approx}2.5 from 3.47 {+-} 0.41 x 10{sup -10} m{sup 2} s{sup -1} at 0.482 MPa to D = 8.55 {+-} 0.33 x 10{sup -10} m{sup 2} s{sup -1} at 2.75 MPa and starts to decrease at higher pressures. An explanation of the observed non-monotonic behavior of the diffusivity in the confined fluid is based on the results of small-angle neutron scattering experiments of the phase behavior of methane in a similar carbon aerogel sample. The initial increase of the diffusion coefficient with pressure is explained as due to progressive filling of bigger pores in which molecular mobility in the internal pore volume is less affected by the sluggish liquid-like molecular mobility in the adsorbed phase. Subsequent decrease of D, is associated with the effect of intermolecular collisions, which result in a lower total molecular mobility with pressure, as in the bulk state. The results are compared with the available QENS data on the methane diffusivity in zeolites, metal organic frameworks, and porous silica as well as with the molecular dynamics simulations of methane in nano-porous carbons and silica zeolites.
Mavila Chathoth, Suresh [ORNL; Mamontov, Eugene [ORNL; Melnichenko, Yuri B [ORNL; Zamponi, Michaela M [ORNL
Characterization of nanostructured zirconia prepared by hydrolysis and reverse micelle synthesis by small-angle neutron and X-ray scattering
Low temperature techniques such as hydrolysis and reverse micelle syntheses provide the opportunity to determine the relationship between the structural properties and preparation conditions of zirconia powders as well as to tailor their physicochemical properties. The authors have performed small-angle neutron and synchrotron X-ray scattering (SANS and SAXS) experiments to study the nucleation and organization of zirconia nanoparticles via different preparation routes. First, the formation of reverse micelles in individual and mixed solutions of (ZrOCl{sub 2}+D{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3}, and (NH{sub 4}OH+H{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3} systems at water/AOT molar ratio of 20 was characterized. Second, the aggregation of zirconia gels obtained from the reaction of the reverse micelle solutions after heat treatments was studied. Third, the nanostructure of zirconia powders prepared by the reverse micelle method is compared with the corresponding powders prepared by hydrolysis after different heat treatments.
Thiyagarajan, P.; Li, X.; Littrell, K.; Seifert, S.; Csencsits, R.; Loong, C.
Small Angle X-Ray Scattering Detector
DOE Patents (OSTI)
A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., qmax/qmin approx=lO0.
Hessler, Jan P.
WAND: Wide-Angle Neutron Diffractometer at HFIR | ORNL Neutron Sciences
US/Japan Wide-Angle Neutron Diffractometer US/Japan Wide-Angle Neutron Diffractometer WAND Instrument scientist Jaime Fernandez-Baca (left) with a visiting researcher at WAND. The Wide-Angle Neutron Diffractometer (WAND) at the HFIR HB-2C beam tube was designed to provide two specialized data-collection capabilities: (1) fast measurements of medium-resolution powder-diffraction patterns and (2) measurements of diffuse scattering in single crystals using flat-cone geometry. For these purposes, this instrument is equipped with a curved, one-dimensional 3He position-sensitive detector covering 125º of the scattering angle with the focal distance of 71 cm. The sample and detector can be tilted in the flat-cone geometry mode. These features enable measurement of single-crystal diffraction patterns in a short time over a
NXS 2010 - Neutron Scattering School
2-26, 2010 2-26, 2010 Argonne National Laboratory, Argonne, IL Oak Ridge National Laboratory, Oak Ridge, TN NXS2010 Travel Airport Shuttles Departure Flights Schedule Participants Lectures Lecturers Lecture Notes/Videos Experiments Schedule, Desc, Groups Student Presentations ANL Facilities APS Facility ANL Map ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIR/SNS Map Access Requirements ANL ORNL Rad Worker Training Study Guide Wireless Networks ANL ORNL Safety & Security Rules ANL ORNL NSSA New Initiatives NSSA Weblink Contacts ANL ORNL 12th National School on Neutron & X-ray Scattering 2009 Neutron Scattering School participants 2010 National School Participants Students share their thoughts about NXS 2010. Purpose: The main purpose of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major neutron and x-ray facilities. Lectures, presented by researchers from academia, industry, and national laboratories, will include basic tutorials on the principles of scattering theory and the characteristics of the sources, as well as seminars on the application of scattering methods to a variety of scientific subjects. Students will conduct four short experiments at Argonne's Advanced Photon Source and Oak Ridge's Spallation Neutron Source and High Flux Isotope Reactor facilities to provide hands-on experience for using neutron and synchrotron sources.
Neutron Scattering Facilities
Gaithersburg, Maryland, USA Peruvian Institute of Nuclear Energy (IPEN), Lima, Peru Spallation Neutron Source, Oak Ridge National Laboratory, Tennessee, USA University of...
NXS 2013 - Neutron Scattering School
5th National School on Neutron and X-Ray Scattering 5th National School on Neutron and X-Ray Scattering August 10-24, 2013 Argonne National Laboratory, Argonne, IL Oak Ridge National Laboratory, Oak Ridge, TN NXS2013 Schedule Participants Image Gallery Travel Info Thank you Lectures Lecture Notes/Videos Experiments ANL Facilities ANL Map (jpg) ANL Map (pdf) ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIR/SNS Map Wireless Networks ORNL Safety & Security Rules ORNL NSSA Weblink Contacts ANL ORNL 2013 NXS School Participants 2013 NXS Participants. NXS interveiws 2013 Click the image to download the video. Video Interviews: Participants answer questions about their experiences at NXS 2011. Your feedback about lectures and experiments is important for evaluating this year's Neutron and X-ray Scattering School and for making improvements for future participants. We sincerely hope that each of you will complete the survey by the end of the school.
Neutron Scatter Camera for Radiaton Detection - Energy ...
Patent 7,741,613: Neutron scatter camera An instrument that will directly image the fast fission neutrons from a special nuclear material source has ...
Neutron Scattering Science User ...
Proposals for beam time at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) and Spallation Neutron Source (SNS) will be accepted via the web-based proposal system...
Neutron-deuteron elastic scattering and three-nucleon force
The differential cross section for neutron-deuteron elastic scattering was measured at six angles over the center-of-mass angular range 65? - 1300? and incident neutron energies 140 - 240 MeV at the LANSCE/WNR facility of ...
Chtangeev, Maxim B
Neutron Scattering Home Page (Low-Graphics)
Home Page A new portal for neutron scattering has just been established at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to...
LANSCE | Lujan Neutron Scattering Center
Department of Energy, National Office of Science Department of Energy, National Office of Science science.energy.gov Department of Energy, National Nuclear Security Administration nnsa.energy.gov Lujan Neutron Scattering Center Logo Lujan Center Mission The Lujan Center delivers science by exploiting the unique characteristics of intense beams of pulsed neutrons for academia, national security, and industry. Lujan Center Vision The Lujan Center will operate a world class user program in the service of the nation. Lujan Center scientists will be recognized for their leadership and innovation in neutron scattering. Lujan Center at LANSCE The Lujan Center is one of five user facilities supported by the LANSCE accelerator which is stewarded. Funding to operate 10 instruments in a national user program is provided by the Department of Energy's Office of
Nanostructure of a-Si:H and related alloys by small-angle scattering of neutrons and X-rays: Annual technical progress report: May 22, 1998 -- May 21, 1999
This report describes work being performed to provide details of the microstructure in high-quality hydrogenated amorphous silicon and related alloys on the nanometer scale. The materials under study are being prepared by state-of-the-art deposition methods, as well as by new and emerging deposition techniques. The purpose is to establish the role of nanostructural features in controlling opto-electronic and photovoltaic properties. The approach centers around the use of the uncommon technique of small-angle scattering of both X-rays (SAXS) and neutrons (SANS). SAXS has already been established as highly sensitive to microvoids and columnar-like microstructure. A major goal of this research is to establish the sensitivity of SANS to the hydrogen nanostructure. Conventional X-ray diffraction techniques are being used to examine medium-range order and microcrystallinity, particularly near the boundary between amorphous and microcrystalline material.
Williamson, D. L.
ORNL Neutron Scattering User Meeting (ONSUM 2011)
and learning about the capabilities of neutron scattering instruments at SNS and HFIR Meeting fellow user scientists and engineers to discuss ongoing research and R&D needs...
International Neutron Scattering Instrumentation School (INSIS...
INSIS 2012 International Neutron Scattering Instrumentation School (INSIS) 15 - 27 July, 2012 INSIS 2012 INFN - Laboratori Nazionali di Frascati * Rome, Italy About the School How...
American Conference on Neutron Scattering 2010 - ORNL Neutron...
Update on Sample Environment Plenary Session: Thom Mason: Neutron Scattering and Energy ACNS website with Program Back to Top an error occurred while processing this directive...
Workshop on Neutron Scattering Applications in Structural Biology...
Workshop on Neutron Scattering Applications in Structural Biology Workshop on Neutron Scattering Applications in Structural Biology For the fourth consecutive year, NScD and JINS...
Phonon Studies with Inelastic Neutron Scattering and First ...
Presentation Title, Phonon Studies with Inelastic Neutron Scattering and .... by Asynchronous In-Situ Neutron Diffraction at the Spallation Neutron Source.
In a concerted effort supported by the National Science Foundation, the Department of Commerce, and the Department of Energy, the United States is rebuilding its leadership in neutron scattering capability through a significant investment in U.S. neutron scattering user facilities and related instrumentation. These unique facilities provide opportunities in neutron scattering to a broad community of researchers from academic institutions, federal laboratories, and industry. However, neutron scattering is often considered to be a tool for 'experts only' and in order for the U.S. research community to take full advantage of these new and powerful tools, a comprehensive education and outreach program must be developed. The workshop described below is the first step in developing a national program that takes full advantage of modern education methods and leverages the existing educational capacity at universities and national facilities. During March 27-28, 2008, a workshop entitled 'Building a Network for Neutron Scattering Education' was held in Washington, D.C. The goal of the workshop was to define and design a roadmap for a comprehensive neutron scattering education program in the United States. Successful implementation of the roadmap will maximize the national intellectual capital in neutron sciences and will increase the sophistication of research questions addressed by neutron scattering at the nation's forefront facilities. (See Appendix A for the list of attendees, Appendix B for the workshop agenda, Appendix C for a list of references. Appendix D contains the results of a survey given at the workshop; Appendix E contains summaries of the contributed talks.) The workshop brought together U.S. academicians, representatives from neutron sources, scientists who have developed nontraditional educational programs, educational specialists, and managers from government agencies to create a national structure for providing ongoing neutron scattering education. A concerted effort was made to involve representatives from historically black colleges and universities (HBCUs) and minority educational institutions (MEIs). The roadmap contained herein provides the path to a national infrastructure for education of students, faculty, and professional researchers who wish to make use of national neutron scattering facilities but do not have (or do not believe they have) the educational background to do so. Education of other stakeholders, including the public, students in kindergarten through twelfth grade (K-12), and policy makers is also included. The opening sessions of the workshop provided the current status of neutron scattering education in North America, Europe, and Australia. National neutron sources have individually developed outreach and advertising programs aimed at increasing awareness among researchers of the potential applications of neutron scattering. However, because their principal mission is to carry out scientific research, their outreach efforts are necessarily self-limiting. The opening session was designed to build awareness that the individual programs need to be coupled with, and integrated into, a broader education program that addresses the complete range of experience, from the student to the experienced researcher, and the wide range of scientific disciplines covered by neutron scattering. Such a program must also take full advantage of existing educational programs and expertise at universities and expand them using modern distance learning capabilities, recognizing that the landscape of education is changing.
Pynn, Roger [ORNL; Baker, Shenda Mary [ORNL; Louca, Despo A [ORNL; McGreevy, Robert L [ORNL; Ekkebus, Allen E [ORNL; Kszos, Lynn A [ORNL; Anderson, Ian S [ORNL
Neutron Sciences - Neutron Scattering Dynamics in Polymer Family
Neutron scattering characterizes dynamics in polymer family Neutron scattering characterizes dynamics in polymer family Research Contact: Christine Gerstl December 2012, Written by Agatha Bardoel Understanding the interplay between structure and dynamics is the key to obtaining tailor-made materials. In the last few years, a large effort has been devoted to characterizing and relating the structure and dynamic properties in families of polymers with alkyl side groups. Now researchers have used quasielastic neutron scattering to investigate the hydrogen dynamics in poly(alkylene oxide)s with different side-chain lengths at temperatures below, as well as above, the glass transition. The combination of techniques and instruments used is bringing a more complete understanding of multiple contributions to system dynamics. The results
Attosecond neutron Compton scattering from protons
The effect of "anomalous" scattering of neutrons and electrons from protons in the electron-volt energy-transfer range is considered, and related experimental results are mentioned. A recent independent confirmation of this effect with a new data analysis procedure is presented. Due to the very short characteristic scattering time, there is no well defined separation of time scales of electronic and protonic motions. An outline of a proposed theoretical interpretation is presented, which is based on the fact that scattering protons represent \\textit{open} quantum systems, thus being subject to decoherence.
C. Aris Chatzidimitriou-Dreismann
Application of neutron scattering to biological and hydrogen ...
... Application of neutron scattering to biological and hydrogen storage materials. Yun Liu, NCNR, NIST. This talk covers two ...
Neutron Scattering Experiment Automation with Python
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.
Zolnierczuk, Piotr A [ORNL; Riedel, Richard A [ORNL
Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions
We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45�, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45� cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.
Vanier P. e.; Dioszegi, I.; Salwen, C.; Forman, L.
Inelastic neutron scattering in valence fluctuation compounds
The valence fluctuation compounds are rare earth intermetallics where hybridization of the nearly-localized 4f electrons with the conduction electrons leads to incorporation of the 4f's into the itinerant states. This hybridization slows down the conduction electrons and hence gives them a heavy effective mass, justifying application of the term 'heavy Fermion' (HF) to these materials. During the project period, we grew large single crystals of several such compounds and measured their properties using both standard thermodynamic probes and state-of-the-art inelastic neutron scattering. We obtained three main results. For the intermediate valence compounds CePd{sub 3} and YbAl{sub 3}, we showed that the scattering of neutrons by the fluctuations of the 4f magnetic moment does not have the momentum dependence expected for the itinerant heavy mass state; rather, the scattering is more typical of a localized spin fluctuation. We believe that incoherent scattering localizes the excitation. For the heavy Fermion compound Ce(Ni{sub 0.935}Pd{sub 0.065}){sub 2}Ge{sub 2}, which sits at a T = 0 critical point for transformation into an antiferromagnetic (AF) phase, we showed that the scattering from the AF fluctuations does not exhibit any of the divergences that are expected at a phase transition. We speculate that alloy disorder profoundly suppresses the growth of the fluctuating AF regions, leading to short range clusters rather than regions of infinite size. Finally, we explored the applicability of key concepts used to describe the behavior of rare earth heavy Fermions to uranium based HF compounds where the 5f electrons are itinerant as opposed to localized. We found that scaling laws relating the spin fluctuation energy measured in neutron scattering to the low temperature specific heat and susceptibility are valid for the uranium compounds, once corrections are made for AF fluctuations; however, the degeneracy of the high temperature moment is smaller than expected for rare-earth-like Hund's rule behavior, essentially because the orbital moment is suppressed for itinerant 5f electrons. We also found that the standard local-moment-based theory of the temperature dependence of the specific heat, susceptibility and neutron scattering fails badly for URu{sub 2}Zn{sub 20} and UCo{sub 2}Zn{sub 20}, even though the theory is phenomenally successful for the closely related rare earth compound YbFe{sub 2}Zn{sub 20}. Both these results highlight the distinction between the itineracy of the 5f's and the localization of the 4f's. It is our hope that these results are sufficiently significant as to stimulate deeper investigation of these compounds.
Jon M Lawrence
Topology of forward scattering of neutrons from imperfect multilayers
Neutrons sent at grazing incidence on imperfect multilayers of polymers are scattered both out of and within the plane of reflection. In the latter geometry the scattered intensity is highly structured in two series of ridges, whose loci can be labeled in terms of the neutron momenta. Intersecting ridges show evidence of mode coupling. Similar topology is expected for x-ray scattering.
Felcher, G.P.; Goyette, R.J. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Anastasiadis, S.; Russell, T.P. (IBM Almaden Research Center, San Jose, California 95120 (United States)); Foster, M.; Bates, F. (Department of Chemical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States))
Development of Lithium Lanthanide Borate Scintillator for Neutron Scattering Applications
We have completed the design and testing of neutron scattering instrument detectors for powder diffractometers and single crystal diffractometers. These detectors meet the performance requirements for these types of instruments at the Department of Energy Spallation Neutron Source facility.
Czirr, J.B.; McKnight, T.; Merrill, D.
ORNL study uses neutron scattering, supercomputing to demystify...
ORNL study uses neutron scattering, supercomputing to demystify forces at play in biofuel production This graphical representation of lignocellulosic biomass based on...
XII SoNS School of Neutron Scattering
XII School of Neutron Scattering (SoNS) XII School of Neutron Scattering (SoNS) "Francesco Paolo Ricci" "Introduction to the theory and techniques of neutron scattering and applications to Cultural Heritage" 30 April - 9 May 2014 A Course within the International School of Solid State Physics ETTORE MAJORANA FOUNDATION AND CENTRE FOR SCIENTIFIC CULTURE, Erice (I) Application deadline: 1 st April 2014 Application is now open for the XII School of Neutron Scattering (SoNS) "Francesco Paolo Ricci": Introduction to the theory and techniques of neutron scattering and applications to Cultural Heritage. The school will be held at the ETTORE MAJORANA FOUNDATION AND CENTRE FOR SCIENTIFIC CULTURE, Erice (Sicily, I) as a specialized course within the International School of Solid State Physics (Director: Giorgio Benedek), between the 30
Scattering of Ultra Cold Neutrons on Nano-size Bubbles
Inelastic scattering of ultra cold neutrons on bubbles with the size of nanometers is considered. It is shown that neutron-bubble cross section is large and sensitive to different vibration modes of bubbles. This process could be used for study of dynamics of nano-size bubbles and for new methods of ultra cold neutron production.
Vladimir Gudkov
2011 U.S. National School on Neutron and X-ray Scattering
The 13th annual U.S. National School on Neutron and X-ray Scattering was held June 11 to 25, 2011, at both Oak Ridge and Argonne National Laboratories. This school brought together 65 early career graduate students from 56 different universities in the US and provided them with a broad introduction to the techniques available at the major large-scale neutron and synchrotron x-ray facilities. This school is focused primarily on techniques relevant to the physical sciences, but also touches on cross-disciplinary bio-related scattering measurements. During the school, students received lectures by over 30 researchers from academia, industry, and national laboratories and participated in a number of short demonstration experiments at Argonne's Advanced Photon Source (APS) and Oak Ridge's Spallation neutron Source (SNS) and High Flux Isotope Reactor (HFIR) facilities to get hands-on experience in using neutron and synchrotron sources. The first week of this year's school was held at Oak Ridge National Lab, where Lab director Thom Mason welcomed the students and provided a shitorical perspective of the neutron and x-ray facilities both at Oak Ridge and Argonne. The first few days of the school were dedicated to lectures laying out the basics of scattering theory and the differences and complementarity between the neutron and x-ray probes given by Sunil Sinha. Jack Carpenter provided an introduction into how neutrons are generated and detected. After this basic introduction, the students received lectures each morning on specific techniques and conducted demonstration experiments each afternoon on one of 15 different instruments at either the SNS or HFIR. Some of the topics covered during this week of the school included inelastic neutron scattering by Bruce Gaulin, x-ray and neutron reflectivity by Chuck Majkrazak, small-angle scattering by Volker Urban, powder diffraction by Ashfia Huq and diffuse scattering by Gene Ice.
Lang, Jonathan [Argonne National Laboratory (ANL); te Vethuis, Suzanne [Argonne National Laboratory (ANL); Ekkebus, Allen E [ORNL; Chakoumakos, Bryan C [ORNL; Budai, John D [ORNL
Neutron scattering characterization of pure and rare-earth modified zirconia catalysis.
The combined application of neutron powder diffraction, small angle neutron scattering and neutron inelastic scattering has led to improved understanding of the crystal phases, defect structure, microstructure and hydroxyl/water dynamics in pure and lanthanide-modified zirconia catalysts. Powder diffraction experiments quantified the degree of stabilization and provided evidence for static, oxygen vacancy-induced atomic displacements in stabilized zirconia. Quantitative assessment of Bragg peak breadths led to measurements of ''grain size'', representing coherency length of long-range ordered atomic arrangements (crystals). Small angle neutron scattering provided a separate measurement of ''grain size'', representing the average size of the primary particles in the aggregates, and the evolution of porosity (micro- versus meso-) and surface roughness caused by RE modification and heat treatment. Finally, the dynamics of hydrogen atoms associated with surface hydroxyls and adsorbed water was investigated by neutron-inelastic scattering, revealing changes in frequency and band breadth of O-H stretch, H-O-H bend, and librational motion of water molecules.
Loong, C.-K.; Ozawa, M.; Richardson, J. W., Jr.; Suzuki, S.; Thiyagarajan, P.
Anomalous Small-angle Scattering with Soft X-rays at Al and Si K ...
Anomalous Small-angle Scattering with Soft X-rays at Al and Si K Absorption ... and Cooling Cycles in a High Strength Quenched and Tempered Structural Steel.
Materials Small-angle X-ray Scattering (SAXS) | Stanford Synchrotron
Materials Small-angle X-ray Scattering (SAXS) Materials Small-angle X-ray Scattering (SAXS) Small Angle X-ray Scattering for Materials Science Small-angle X-ray scattering (SAXS) is a well-established characterization method for microstructure investigations in various materials. It probes electron density differences to give information about structural inhomogeneities from the near atomic scale (1 nm) to the micron scale (1 000 nm). The method involves measuring the scattered X-ray intensity as a function of (typically small) scattering angles and is generally performed in transmission. SAXS is used to characterize the size scale of inhomogeneities (e.g. pores, inclusions, second phase regions) in polymer blends, micro-emulsions, geological materials, bones, cements and ceramics. Instrumentation
Neutron Scattering | U.S. DOE Office of Science (SC)
Office of Science (SC) Website
Neutron Scattering Neutron Scattering Materials Sciences and Engineering (MSE) Division MSE Home About Research Areas Energy Frontier Research Centers (EFRCs) DOE Energy Innovation Hubs BES Funding Opportunities The Computational Materials and Chemical Sciences Network (CMCSN) Theoretical Condensed Matter Physics Scientific Highlights Reports and Activities Principal Investigators' Meetings BES Home Research Areas Neutron Scattering Print Text Size: A A A RSS Feeds FeedbackShare Page This activity supports basic research on the fundamental interactions of neutrons with matter to achieve an understanding of the atomic, electronic, and magnetic structures and excitations of materials and their relationship to materials properties. Major emphasis is on the application of neutron scattering, spectroscopy, and imaging for materials research, primarily at
Deterministic Multigroup Modeling of Thermal Effect on Neutron Scattering by Heavy Nuclides.
??The principal physical phenomenon underlying the computation of neutron spectra is the nuclear reaction in which neutrons lose or gain energy, i.e., the neutron scattering� (more)
Ghrayeb, Shadi
Measurement of the Weak Mixing Angle in Moller Scattering
The weak mixing parameter, sin{sup 2} {theta}{sub w}, is one of the fundamental parameters of the Standard Model. Its tree-level value has been measured with high precision at energies near the Z{sup 0} pole; however, due to radiative corrections at the one-loop level, the value of sin{sup 2} {theta}{sub w} is expected to change with the interaction energy. As a result, a measurement of sin{sup 2} {theta}{sub w} at low energy (Q{sup 2} << m{sub Z}, where Q{sup 2} is the momentum transfer and m{sub Z} is the Z boson mass), provides a test of the Standard Model at the one-loop level, and a probe for new physics beyond the Standard Model. One way of obtaining sin{sup 2} {theta}{sub w} at low energy is from measuring the left-right, parity-violating asymmetry in electron-electron (Moeller) scattering: A{sub PV} = {sigma}{sub R}-{sigma}{sub L}/{sigma}{sub R}+{sigma}{sub L}, where {sigma}{sub R} and {sigma}{sub L} are the cross sections for right- and left-handed incident electrons, respectively. The parity violating asymmetry is proportional to the pseudo-scalar weak neutral current coupling in Moeller scattering, g{sub ee}. At tree level g{sub ee} = (1/4 -sin{sup 2} {theta}{sub w}). A precision measurement of the parity-violating asymmetry in Moeller scattering was performed by Experiment E158 at the Stanford Linear Accelerator Center (SLAC). During the experiment, {approx}50 GeV longitudinally polarized electrons scattered off unpolarized atomic electrons in a liquid hydrogen target, corresponding to an average momentum transfer Q{sup 2} {approx} 0.03 (GeV/c){sup 2}. The tree-level prediction for A{sub PV} at such energy is {approx}300 ppb. However one-loop radiative corrections reduce its value by {approx}40%. This document reports the E158 results from the 2002 data collection period. The parity-violating asymmetry was found to be A{sub PV} = -160 {+-} 21 (stat.) {+-} 17 (syst.) ppb, which represents the first observation of a parity-violating asymmetry in Moeller scattering. This value corresponds to a weak mixing angle at Q{sup 2} = 0.026 (GeV/c){sup 2} of sin{sup 2} {theta}{sub w{ovr MS}} = 0.2379 {+-} 0.0016 (stat.) {+-} 0.0013 (syst.), which is -0.3 standard deviations away from the Standard Model prediction: sin{sup 2} {theta}{sub w{ovr MS}}{sup predicted} = 0.2385 {+-} 0.0006 (theory). The E158 measurement of sin{sup 2} {theta}{sub w} at a precision of {delta}(sin{sup 2} {theta}{sub w}) = 0.0020 provides new physics sensitivity at the TeV scale.
Klejda, B.
Neutron beam characterization measurements at the Manuel Lujan Jr. neutron scattering center
We have measured the neutron beam characteristics of neutron moderators at the Manuel Lujan Jr. Neutron Scattering Center at LANSCE. The absolute thermal neutron flux, energy spectra and time emission spectra were measured for the high resolution and high intensity decoupled water, partially coupled liquid hydrogen and partially coupled water moderators. The results of our experimental study will provide an insight into aging of different target-moderator-reflector-shield components as well as new experimental data for benchmarking of neutron transport codes.
Mocko, Michal [Los Alamos National Laboratory; Muhrer, Guenter [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Kelsey, Charles T [Los Alamos National Laboratory; Duran, Michael A [Los Alamos National Laboratory; Tovesson, Fredrik K [Los Alamos National Laboratory
Angle-resolved scattering spectroscopy of explosives using an external cavity quantum cascade laser
Investigation of angle-resolved scattering from solid explosives residues on a car door for non-contact sensing geometries. Illumination with a mid-infrared external cavity quantum cascade laser tuning between 7 and 8 microns was detected both with a sensitive single point detector and a hyperspectral imaging camera. Spectral scattering phenomena were discussed and possibilities for hyperspectral imaging at large scattering angles were outlined.
Suter, Jonathan D.; Bernacki, Bruce E.; Phillips, Mark C.
Measurements of the Thermal Neutron Scattering Kernel
world's most powerful neutron source, the $1.4 billion Spallation Neutron Source At 1.4MW, SNS produces. SNS will feature 24 beamlines for physics, chemistry, biology, materials research. www.sns.gov #12 · Coproduction of epithermal, thermal and cold neutrons #12;SNS Instrument Beam Lines 1st experimentproposed 2nd
Danon, Yaron
Small and Intermediate-Angle Scattering Instruments for Materials ...
It is becoming clear that even at such low power sources, we can conduct ... Scattering Methods for Investigations on Magnetic Thin Film Nanostructures.
Investigating Microscopic Heat Transport with Neutron Scattering
In-Situ Neutron Diffraction and Crystal Plasticity Modeling of a-Uranium � In-Situ Studies of the ... Thermal Residual Stresses and Strains in Depleted Uranium.
Neutron Scattering Analysis of Magnetostructural Phase ...
Experiments to observe the structural and magnetic phase transformations were performed at the Spallation Neutron Source (SNS) at Oak Ridge National�...
Small-angle Compton Scattering to Determine the Depth of a Radioactive Source in Matter
A gamma-ray peak in a spectrum is often accompanied by a discontinuity in the Compton continuum at the peak. The Compton continuum results from Compton scattering in the detector. The discontinuity at a peak results from small-angle Compton scattering by the gamma rays in matter situated directly between the gamma-ray source and the detector. The magnitude of this discontinuity with respect to the gamma-ray peak is therefore an indicator of the amount of material or shielding between the gamma-ray source and the detector. This small-angle scattering was used to determine the depth of highly-enriched uranium (HEU) solution standards in a concrete floor mockup. The empirical results of the use of this small-angle scattering discontinuity in a concrete floor experiment will be described. A Monte Carlo calculation of the experiment will also be described. In addition, the depth determined from small-angle scattering was used in conjunction with differential attenuation to more accurately measure the uranium content of the mockup. Following these empirical results, the theory of small-angle scattering will be discussed. The magnitude of the discontinuity compared to the peak count rate is directly related to the depth of the gamma-ray source in matter. This relation can be described by relatively simple mathematical expressions. This is the first instance that we are aware of in which the small-angle Compton scattering has been used to determine the depth of a radioactive source. Furthermore this is the first development of the theoretical expressions for the magnitude of the small-angle scattering discontinuity.
Oberer, R. B.; Gunn, C. A.; Chiang, L. G.; Valiga, R. E.; Cantrell, J. A.
Neutron Diffraction Study of Crystal Structure and Magnetic ...
Abstract Scope, Magnetic refrigeration based on the magnetocaloric effect ... Small and Wide Angle Neutron Scattering for Industrial Applications at HANARO.
Neutron and X-Ray Scattering - Argonne National Laboratories, Materials
Home Home Neutron and X-Ray Scattering Neutron and X-ray Scattering Science Recent advances in neutron and x-ray scattering instrumentation at major DOE facilities such as the Spallation Neutron Source and Advanced Photon Source provide unprecedented insights into complex phenomena in bulk and interfacial materials. The vision of our group is to harness the complementarity of neutrons and x-rays to study how materials respond on a range of length and time scales to phase competition, so that we can learn to control emergent behavior and generate functional properties in energy-related materials. We use neutrons and x-rays to investigate the structure and dynamics of bulk and interfacial materials with properties that are useful for energy applications, such as superconductivity, magnetism and thermoelectricity. Phase competition can generate or enhance such properties, but it is extremely challenging to characterize fluctuations in the competing order, whether in bulk disordered materials, or artificial heterostructures. Our goal is to utilize efficient techniques that we have been developing for measuring nanoscale phase fluctuations, both static and dynamic, to enable the rational design of new materials for energy within MSD.
Nondispersive neutron focusing method beyond the critical angle of mirrors
This invention extends the Kirkpatrick-Baez (KB) mirror focusing geometry to allow nondispersive focusing of neutrons with a convergence on a sample much larger than is possible with existing KB optical schemes by establishing an array of at least three mirrors and focusing neutrons by appropriate multiple deflections via the array. The method may be utilized with supermirrors, multilayer mirrors, or total external reflection mirrors. Because high-energy x-rays behave like neutrons in their absorption and reflectivity rates, this method may be used with x-rays as well as neutrons.
Ice, Gene E. (Oak Ridge, TN)
... Are there nuclear reactors that use non-enriched Uranium? ... therefore yielding very high wavelength resolution ... is useful for highly ordered samples ...
Small-Angle Neutron Scattering from Deuterated Polystyrene ...
... Helfand and Fre- dri~kson'~ have used a set of coupled hydrodynamic equations with inhomogeneous transport coefficients (shear viscosity and ...
Application of Small Angle Neutron Scattering to Analyze Nano ...
The trivalent chromium contained nano-sized cracks due to hydrogen evolution and abnormal growth of metallic chromium. Layer-by-layer deposition of nickel�...
Instrument - NG7 SANS - Small Angle Neutron Scattering
... Jointly developed and sponsored by the NCNR, the ExxonMobil Research and Engineering Co., and the University of Minnesota, the instrument ...
Pore accessibility by methane and carbon dioxide in coal as determined by neutron scattering
Contrast-matching ultrasmall-angle neutron scattering (USANS) and small-angle neutron scattering (SANS) techniques were used for the first time to determine both the total pore volume and the fraction of the pore volume that is inaccessible to deuterated methane, CD{sub 4}, in four bituminous coals in the range of pore sizes between {approx}10 {angstrom} and {approx}5 {micro}m. Two samples originated from the Illinois Basin in the U.S.A., and the other two samples were commercial Australian bituminous coals from the Bowen Basin. The total and inaccessible porosity were determined in each coal using both Porod invariant and the polydisperse spherical particle (PDSP) model analysis of the scattering data acquired from coals both in vacuum and at the pressure of CD{sub 4}, at which the scattering length density of the pore-saturating fluid is equal to that of the solid coal matrix (zero average contrast pressure). The total porosity of the coals studied ranged from 7 to 13%, and the volume of pores inaccessible to CD{sub 4} varied from {approx}13 to {approx}36% of the total pore volume. The volume fraction of inaccessible pores shows no correlation with the maceral composition; however, it increases with a decreasing total pore volume. In situ measurements of the structure of one coal saturated with CO{sub 2} and CD{sub 4} were conducted as a function of the pressure in the range of 1-400 bar. The neutron scattering intensity from small pores with radii less than 35 {angstrom} in this coal increased sharply immediately after the fluid injection for both gases, which demonstrates strong condensation and densification of the invading subcritical CO{sub 2} and supercritical methane in small pores.
He, Lilin [ORNL; Melnichenko, Yuri B [ORNL; Mastalerz, Maria [Indiana Geological Survey; Sakurovs, Richard [ORNL; Radlinski, Andrzej Pawell [ORNL; Blach, Tomasz P [ORNL
Neutron Form Factor from Neutrino-Nucleus Coherent Elastic Scattering
We analyze the prospect of measuring the neutron form factor of a nucleus through the detection of neutrino-nucleus coherent elastic scattering. We predict numbers of events in a liquid noble nuclear recoil detector at a stopped pion neutrino source. We discuss the precision required to distinguish between different theoretical models for the form factor.
Philip S. Amanik; Gail C. McLaughlin
A workshop on enhanced national capability for neutron scattering
This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron scattering landscape assuming full utilization of beamlines, a refurbished LANSCE, and a 1.4-MW SNS. Because the Lujan Strategic Plan is intended to set the stage for the Signature Facility era at LANSCE, there will be some discussion of the long-pulse spallation source at Los Alamos. Breakout groups will cover several new instrument concepts, upgrades to present instruments, expanded sample environment capabilities, and a look to the future. The workshop is in keeping with a request by BES to update the Lujan strategic plan in coordination with the SNS and the broader neutron community. Workshop invitees will be drawn from the LANSCE User Group and a broad cross section of the US, European, and Pacific Rim neutron scattering research communities.
Hurd, Alan J [Los Alamos National Laboratory; Rhyne, James J [Los Alamos National Laboratory; Lewis, Paul S [Los Alamos National Laboratory
Science | ORNL Neutron Sciences
Neutron Science Neutron Science Neutron Scattering Science Neutrons are one of the fundamental particles that make up matter and have properties that make them ideal for certain types of research. In the universe, neutrons are abundant, making up more than half of all visible matter. Neutron scattering provides information about the positions, motions, and magnetic properties of solids. When a beam of neutrons is aimed at a sample, many neutrons will pass through the material. But some will interact directly with atomic nuclei and "bounce" away at an angle, like colliding balls in a game of pool. This behavior is called neutron diffraction, or neutron scattering. Using detectors, scientists can count scattered neutrons, measure their energies and the angles at which they scatter, and map their final position
Pitch angle scattering of relativistic electrons from stationary magnetic waves: Continuous Markov process and quasilinear theory
We develop a Markov process theory of charged particle scattering from stationary, transverse, magnetic waves. We examine approximations that lead to quasilinear theory, in particular the resonant diffusion approximation. We find that, when appropriate, the resonant diffusion approximation simplifies the result of the weak turbulence approximation without significant further restricting the regime of applicability. We also explore a theory generated by expanding drift and diffusion rates in terms of a presumed small correlation time. This small correlation time expansion leads to results valid for relatively small pitch angle and large wave energy density - a regime that may govern pitch angle scattering of high-energy electrons into the geomagnetic loss cone.
Lemons, Don S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
A Neutron Scattering Kernel of Solid Methane in phase II
A neutron scattering cross section model for solid methane was studied in the temperature ranges of 20.4$\\sim$4K. The analytical scattering kernel was adapted from Ozaki.$\\it{et al.}$\\cite{ozaki:3442}\\cite{ozaki2} to describe molecular rotation in this temperature range. This model includes a molecular translation and intramolecular vibration as well as the rotational degree of freedom in effective ways. Total scattering cross sections were calculated from the model and evaluated by comparing with the cross section measurement of Grieger\\cite{grieger:3161} and Whittemore\\cite{Wittemore} for incident neutron energy of 0.1 \\textit{meV} $\\sim$ 1\\textit{eV}. We produced frequency spectra from the model in the temperature range. The results were also compared with the Harker $&$ Brugger frequency spectrum at 22K\\cite{HARKER1967}. For broader applications, neutron scattering kernels for MCNP (Monte Carlo N Particle Transport Code) were produced at 20K and 4K from the frequency spectra using NJOY code. The scatt...
Shin, Yunchang; Liu, Chen-yu; Lavelle, Christopher M; Baxter, David V
2009 International Conference on Neutron Scattering (ICNS 2009)
The ICNS provides a focal point for the worldwide neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as �?¢�?�?�?�?would-be�?¢�?�?�? neutron users. The International Conference on Neutron Scattering thus serves a dual role as an international user meeting and a scientific meeting. As a venue for scientific exchange, the ICNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. Each of the major national neutron facilities (NIST, LANSCE, ANL, HFIR and SNS), along with their international counterparts, has an opportunity to exchange information with each other and to update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities.
Gopal Rao, PhD; Donna Gillespie
Synthesis and characterization of nanophase zirconia : reverse micelle method and neutron scattering study.
Zirconia is an important transition-metal oxide for catalytic applications. It has been widely used in automotive exhaust treatment, methanol synthesis, isomerization, alkylation, etc. [1]. Nanophase materials have unique physiochemical properties such as quantum size effects, high surface area, uniform morphology, narrow size distribution, and improvement of sintering rates[2]. Microemulsion method provides the means for controlling the microenvironment under which specific chemical reactions may occur in favoring the formation of homogeneous, nanometer-size particles. In this paper, we report the synthesis of nanophase zirconia and the characterization of the microemulsions as well as the powders by small- and wide-angle neutron scattering techniques.
Li, X.
Introduction to Neutron and X-Ray Scattering
Scattering Studies of Thin Scattering Studies of Thin Polymer Films Introduction to Neutron and X-Ray Scattering Sunil K. Sinha UCSD/LANL Acknowledgements: Prof. R.Pynn( Indiana U.) Prof. M.Tolan (U. Dortmund) Wilhelm Conrad Röntgen 1845-1923 1895: Discovery of X-Rays 1901 W. C. Röntgen in Physics for the discovery of x-rays. 1914 M. von Laue in Physics for x-ray diffraction from crystals. 1915 W. H. Bragg and W. L. Bragg in Physics for crystal structure determination. 1917 C. G. Barkla in Physics for characteristic radiation of elements. 1924 K. M. G. Siegbahn in Physics for x-ray spectroscopy. 1927 A. H. Compton in Physics for scattering of x-rays by electrons. 1936 P. Debye in Chemistry for diffraction of x-rays and electrons in gases.
CORELLI: the Elastic Diffuse Scattering Spectrometer at SNS | ORNL Neutron
The Elastic Diffuse Scattering Spectrometer The Elastic Diffuse Scattering Spectrometer CORELLI The CORELLI instrument. CORELLI is a statistical chopper spectrometer with energy discrimination. It's designed and optimized to probe complex disorder in crystalline materials through diffuse scattering of single-crystal samples. The momentum transfer ranges from 0.5 to 12 Å-1, and the energy of incident neutrons ranges from 10 to 200 meV. This instrument combines the high efficiency of white-beam Laue diffraction with energy discrimination by modulating the beam with a statistical chopper. A cross-correlation method is used to reconstruct the elastic signal from the modulated data. Accurate modeling of the short-range order associated with the diffuse scattering requires measurements over large volumes of three-dimensional reciprocal space, with sufficient momentum
Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis
This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.
Meyer, Matthew W. [Ames Laboratory
Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis
This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.
Overbury, Steven {Steve} H [ORNL; Coates, Leighton [ORNL; Herwig, Kenneth W [ORNL; Kidder, Michelle [ORNL
Neutron and Synchrotron X-Ray Scattering Studies of Superconductors
Superconductors hold the promise for a more stable and efficient electrical grid, but new isotropic, high-temperature superconductors are needed in order to reduce cable manufacturing costs. The effort to understand high-temperature superconductivity, especially in the layered cuprates, provides guidance to the search for new superconductors. Neutron scattering has long provided an important probe of the collective excitations that are involved in the pairing mechanism. For the cuprates, neutron and x-ray diffraction techniques also provide information on competing types of order, such as charge and spin stripes, that appear to be closely connected to the superconductivity. Recently, inelastic x-ray scattering has become competitive for studying phonons and may soon provide valuable information on electronic excitations. Examples of how these techniques contribute to our understanding of superconductivity are presented.
Coulomb Correction to the Screening Angle of the Moliere Multiple Scattering Theory
High-energy Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory is found. Numerical calculations are presented in the range of nuclear charge from Z=4 to Z=82. Comparison with the Moliere result for the screening angle reveals up to 30% deviation from it for sufficiently heavy elements of the target material.
E. A. Kuraev; O. O. Voskresenskaya; A. V. Tarasov
Scientific opportunities with advanced facilities for neutron scattering
The present report documents deliberations of a large group of experts in neutron scattering and fundamental physics on the need for new neutron sources of greater intensity and more sophisticated instrumentation than those currently available. An additional aspect of the Workshop was a comparison between steady-state (reactor) and pulsed (spallation) sources. The main conclusions were: (1) the case for a new higher flux neutron source is extremely strong and such a facility will lead to qualitatively new advances in condensed matter science and fundamental physics; (2) to a large extent the future needs of the scientific community could be met with either a 5 x 10/sup 15/ n cm/sup -2/s/sup -1/ steady state source or a 10/sup 17/ n cm/sup -2/s/sup -1/ peak flux spallation source; and (3) the findings of this Workshop are consistent with the recommendations of the Major Materials Facilities Committee.
Lander, G.H.; Emery, V.J. (eds.)
BIOISIS: Biological Macromolecules by Small Angle X-ray Scattering (SAXS)
DOE Data Explorer (OSTI)
BIOISIS is an open access database dedicated to the study of biological macromolecules by small angle X-ray scattering (SAXS). BIOISIS aims to become the complete source for the deposition, distribution and maintenance of small angle X-ray scattering data and technologies. The database is designed around the concept of an �experiment� and relates a specific experiment to a set of genes, organisms, computational models and experimental data. As of May 2012, BIOSIS contains 7,118 genes covering four different organisms. Forty-two modeled structures are available. Clicking on a structures reveals scattering curves, experimental conditions, and experimental values. The data are collected at Beamline 12.3.1 of the Advanced Light Source (ALS).[Copied with editing from http://www.bioisis.net/about
Tainer, John (Scripps Research Institute); Hura, Greg (LBNL); Rambo, Robert P. (LBNL)
Research Highlights | ORNL Neutron Sciences
Polytechnic Institute used small-angle neutron scattering (SANS) at the High-Flux Isotope Reactor at Oak Ridge National Laboratory to identify these early stage aggregates in...
Neutron Scattering Facilities | U.S. DOE Office of Science (SC)
Neutron Scattering Facilities Neutron Scattering Facilities Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Nanoscale Science Research Centers Electron-Beam Microcharacterization Centers Accelerator & Detector Research & Development Principal Investigators' Meetings Scientific Highlights Construction Projects BES Home User Facilities Neutron Scattering Facilities Print Text Size: A A A RSS Feeds FeedbackShare Page This activity supports the operation of three DOE neutron scattering facilities, which are unique and effective tools for probing the structure of matter. Neutron scattering is particularly well-suited for determining the atomic positions of both light and heavy atoms in a solid and thermal fluctuations in these positions. In addition the neutron
School on Neutron and X-ray Scattering Oak Ridge 10-24 August 2013 John M. Carpenter ANL, ORNLSNS 18 August 2013 2 Neutron Detection How does one detect a neutron? - It is...
Research article: Monte Carlo-based rigid body modelling of large protein complexes against small angle scattering data
We present a modular, collaborative, open-source architecture for rigid body modelling based upon small angle scattering data, named sas_rigid. It is designed to provide a fast and extensible scripting interface using the easy-to-learn Python programming ... Keywords: Hemocyanin, Monte Carlo with simulated annealing, Rigid body modelling, Small angle scattering (SAS)
Christian Meesters; Bruno Pairet; Anja Rabenhorst; Heinz Decker; Elmar Jaenicke
Note: Grazing incidence small and wide angle x-ray scattering combined with imaging ellipsometry
The combination of grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) with optical imaging ellipsometry is presented as an upgrade of the available measurement techniques at the wiggler beamline BW4 of the Hamburger Synchrotronstrahlungslabor. The instrument is introduced with the description of the alignment procedure to assure the measurement of imaging ellipsometry and GISAXS/GIWAXS on the same sample spot. To demonstrate the possibilities of the new instrument examples of morphological investigation on films made of poly(3-hexylthiophene) and [6,6]-phenyl-C{sub 61} butyric acid methyl ester as well as textured poly(9,9-dioctylfluorene-alt-benzo-thia-diazole) are shown.
Koerstgens, V.; Meier, R.; Ruderer, M. A.; Guo, S.; Chiang, H.-Y.; Mueller-Buschbaum, P. [Technische Universitaet Muenchen, Physik-Department, Lehrstuhl fuer Funktionelle Materialien, James-Franck-Str. 1, 85748 Garching (Germany); Perlich, J.; Roth, S. V.; Gehrke, R. [HASYLAB, DESY, Notkestr. 85, 22607, Hamburg (Germany)
Clifford G. Shull: A Memoir of a Pioneer in Neutron Scattering
Clifford G. Shull: A Memoir of a Pioneer in Neutron Scattering. ... The memoir is a history, a love story, and an allegory on how to practice science. ...
Compact D-D/D-T neutron generators and their applications
cold neutrons have an excellent resolution for the fusion-the fusion-based neutron source is more suitable for coldCold neutron source for Small Angle Neutron Scattering51 5.4 Summary of fusion-
Lou, Tak Pui
Fast Lidar and Radar Multiple-Scattering Models. Part II: Wide-Angle Scattering Using the Time-Dependent Two-Stream Approximation
Spaceborne lidar returns from liquid water clouds contain significant contributions from photons that have experienced many wide-angle multiple-scattering events, resulting in returns appearing to originate from far beyond the end of the cloud. A ...
Robin J. Hogan; Alessandro Battaglia
... 4 NG-7 30m SANS Small Angle Neutron Scattering instrument for microstructure measurement sponsored by NIST, the Exxon Research and ...
News Releases and Features | Neutron Science | ORNL
June 29, 2012 - Bio-SANS, the Biological Small-Angle Neutron Scattering Instrument at HFIR recently had a detector upgrade that will provide significantly improved performance...
... 4 NG-7 30 m SANS Small Angle Neutron Scattering instrument for microstructure measurement sponsored by NIST, the ExxonMobil Research ...
A Precision Low-Energy Measurement of the Weak Mixing Angle in Moller Scattering
The E-158 experiment at the Stanford Linear Accelerator Center (SLAC) measures the parity-violating cross-section asymmetry in electron-electron (Moeller) scattering at low Q{sup 2}. This asymmetry, whose Standard Model prediction is roughly -150 parts per billion (ppb), is directly proportional to (1-4 sin{sup 2} {theta}{sub W}), where {theta}{sub W} is the weak mixing angle. Measuring this asymmetry to within 10% provides an important test of the Standard Model at the quantum loop level and probes for new physics at the TeV scale. The experiment employs the SLAC 50 GeV electron beam, scattering it off a liquid hydrogen target. A system of magnets and collimators is used to isolate and focus the Moeller scattering events into an integrating calorimeter. The electron beam is generated at the source using a strained, gradient-doped GaAs photocathode, which produces roughly 5 x 10{sup 11} electrons/pulse (at a beam rate of 120 Hz) with {approx} 80% longitudinal polarization. The helicity of the beam can be rapidly switched, eliminating problems associated with slow drifts. Helicity-correlations in the beam parameters (charge, position, angle and energy) are minimized at the source and corrected for using precision beam monitoring devices.
Mastromarino, P.
Calibration of neutron-yield diagnostics in attenuating and scattering environments
We have performed absolute calibrations of a fusion-neutron-yield copper-activation diagnostic in environments that significantly attenuate and scatter neutrons. We have measured attenuation and scattering effects and have compared the measurements to Monte Carlo simulations using the Monte Carlo N-Particle code. We find that measurements and simulations are consistent within 10%.
Hahn, K. D.; Ruiz, C. L.; Chandler, G. A.; Leeper, R. J.; McWatters, B. R.; Smelser, R. M.; Torres, J. A. [Sandia National Laboratories, Diagnostics and Target Physics, Albuquerque, New Mexico 87111 (United States); Cooper, G. W.; Nelson, A. J. [University of New Mexico, Department of Chemical and Nuclear Engineering, Albuquerque, New Mexico 87131 (United States)
Neutron total and scattering cross sections of /sup 6/Li in the few MeV region
Neutron total cross sections of /sup 6/Li are measured from approx. 0.5 to approx. 4.8 MeV at intervals of approx. 10 scattering angles and at incident-neutron intervals of approx.< 100 keV. Neutron differential inelastic-scattering cross sections are measured in the incident-energy range 3.5 to 4.0 MeV. The experimental results are extended to lower energies using measured neutron total cross sections recently reported elsewhere by the authors. The composite experimental data (total cross sections from 0.1 to 4.8 MeV and scattering cross sections from 0.22 to 4.0 MeV) are interpreted in terms of a simple two-level R-matrix model which describes the observed cross sections and implies the reaction cross section in unobserved channels; notably the (n;..cap alpha..)t reaction (Q = 4.783 MeV). The experimental and calculational results are compared with previously reported results as summarized in the ENDF/B-V evaluated nuclear data file.
Smith, A.; Guenther, P.; Whalen, J.
Elevation angle alignment of quasi optical receiver mirrors of collective Thomson scattering diagnostic by sawtooth measurements
Localized measurements of the fast ion velocity distribution function and the plasma composition measurements are of significant interest for the fusion community. Collective Thomson scattering (CTS) diagnostics allow such measurements with spatial and temporal resolution. Localized measurements require a good alignment of the optical path in the transmission line. Monitoring the alignment during the experiment greatly benefits the confidence in the CTS measurements. An in situ technique for the assessment of the elevation angle alignment of the receiver is developed. Using the CTS diagnostic on TEXTOR without a source of probing radiation in discharges with sawtooth oscillations, an elevation angle misalignment of 0.9 Degree-Sign was found with an accuracy of 0.25 Degree-Sign .
Moseev, D. [FOM DIFFER - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Nieuwegein (Netherlands); Max-Planck-Institut fuer Plasmaphysik, Euratom Association-IPP, 85748 Garching (Germany); Meo, F.; Korsholm, S. B.; Leipold, F.; Michelsen, P. K.; Nielsen, S. K.; Salewski, M.; Stejner, M. [Association EURATOM - DTU, Department of Physics, Technical University of Denmark, Riso Campus, 4000 Roskilde (Denmark); Bindslev, H. [Faculty of Science and Technology, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Furtula, V. [Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Kantor, M. [FOM DIFFER - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Nieuwegein (Netherlands); FZ Juelich GmbH, EURATOM, Trilateral Euregio Cluster, D-52425 Juelich (Germany); Ioffe Institute, RAS, Saint Petersburg 194021 (Russian Federation)
A brief History of Neutron Scattering at the Oak Ridge High Flux Isotope Reactor
Neutron scattering at the Oak Ridge National Laboratory dates back to 1945 when Ernest Wollan installed a modified x-ray diffractometer on a beam port of the original graphite reactor. Subsequently, Wollan and Clifford Shull pioneered neutron diffraction and laid the foundation for an active neutron scattering effort that continued through the 1950s, using the Oak Ridge Research reactor after 1958, and, starting in 1966, the High Flux Isotope Reactor, or HFIR.
Nagler, Stephen E [ORNL; Mook Jr, Herbert A [ORNL
Naysaying the Neutron Scattering Society Lawrence Cranberg, Jill Trewhella, and Henry R. Glyde
The New Munich Neutron Source FRM II: Overview and Uses for Biological Studies Wolfgang Doster Technical University Munich, Physics Department E 13, D-85748 Garching, Email: firstname.lastname@example.com Abstract. The application of neutron scattering to biological systems using the new neutron source in Munich is discussed
Glyde, Henry R.
Precision Beam Parameter Monitoring in a Measurement of the Weak Mixing Angle in Moeller Scattering
A precision measurement of the parity nonconserving left-right asymmetry, A{sub LR}, in Moeller scattering (e{sup -}e{sup -} {yields} e{sup -}e{sup -}) is currently in progress at the Stanford Linear Accelerator Center (SLAC). This experiment, labeled SLAC-E158, scatters longitudinally polarized electrons off atomic electrons in an unpolarized hydrogen target at a Q{sup 2} of 0.03 (GeV/c){sup 2}. The asymmetry, which is the fractional difference in the scattering cross-sections, measures the effective pseudo-scalar weak neutral current coupling, g{sub ee}, governing Moeller scattering. This quantity is in turn proportional to (1/4 - sin{sup 2} {theta}{sub w}), where {theta}{sub w} is the electroweak mixing angle. The goal is to measure the asymmetry to a precision of 1 x 10{sup -8} which corresponds to {delta}(sin{sup 2} {theta}{sub w}) {approx} 0.0007. Since A{sub LR} is a function of the cross-sections, and the cross-sections depend on the beam parameters, the desired precision of A{sub LR} places stringent requirements on the beam parameters. This paper investigates the requirements on the beam parameters and discusses the means by which they are monitored and accounted for.
Cooke, M.S.
Neutron scattering analysis with microscopic optical model potentials
A review of microscopic optical model potentials used in the analysis of neutron scattering and analyzing power data below 100 MeV (5 {le}E{sub n}{le}100 MeV) is presented. The quality of the fits to the data over a wide massd ({sup 6}Li-{sup 239}Pu) and energy range is discussed. It is shown that reasonably good agreement with the data is obtained with only three parameters, {lambda}{sub V}, {lambda}{sub W}, and {lambda}{sub SO}, which show a smooth mass and energy dependence. These parameters are normalizing constants to the real (V), and imaginary (W) central potentials and the real spin-orbit (V{sub SO}) potential. 14 refs., 7 figs.
Hansen, L.F.
Time-Resolved Small-Angle X-ray Scattering Studies Revealed Three Kinetic
June 2010 June 2010 Time-Resolved Small-Angle X-ray Scattering Studies Revealed Three Kinetic Stages of a T=4 Virus Maturation Most eukaryotic viruses, including HIV, influenza and herpes viruses, undergo maturation when transitioning from the noninfectious provirion to the infectious virion. Maturation processes involve reorganization of viral quaternary structure to defend viral gene from the cellular defense mechanism and lead to effective transfection. Nudaurelia capensis omega virus, NwV, is a T=4, non-enveloped, icosahedral, single strand RNA virus, where T is the triangulation number defining an icosahedral lattice of the virus capsid structure. Virus like particles (VLPs) of NwV exhibit large pH-dependent conformational changes (LCC) when the procapsid, purified at pH=7.6, (~480 Å) is exposed to pH=5.0, resulting in ~400 Å particles (Figure 1). In response to the LCC, an auto-proteolysis occurs in which each of 240 subunits is cleaved at Asn570-Phe571 (1). We investigated this pH-induced maturation by equilibrium and time-resolved small angle X-ray scattering (SAXS) at SSRL beam line 4-2.
Thirteenth National School on Neutron and X-ray Scattering
Spallation-Driven Cold Neutron Sources Dr. Bradley J. Micklich Senior Physicist, Physics Division physics research Want neutron wavelengths about the dimensions of interest, or neutron energies that can using an intense source of longerwavelength neutrons fundamental nuclear physics (neutron halflife
Applied Neutron Scattering in Engineering and Materials Science ...
Neutron Diffraction Studies of Residual Stresses around Gouges and Gouged Dents in Pipelines � Neutron Diffraction Study and EVPSC Modeling of the�...
Robust, high-throughput solution structural analyses by small angle X-ray scattering (SAXS)
We present an efficient pipeline enabling high-throughput analysis of protein structure in solution with small angle X-ray scattering (SAXS). Our SAXS pipeline combines automated sample handling of microliter volumes, temperature and anaerobic control, rapid data collection and data analysis, and couples structural analysis with automated archiving. We subjected 50 representative proteins, mostly from Pyrococcus furiosus, to this pipeline and found that 30 were multimeric structures in solution. SAXS analysis allowed us to distinguish aggregated and unfolded proteins, define global structural parameters and oligomeric states for most samples, identify shapes and similar structures for 25 unknown structures, and determine envelopes for 41 proteins. We believe that high-throughput SAXS is an enabling technology that may change the way that structural genomics research is done.
Hura, Greg L.; Menon, Angeli L.; Hammel, Michal; Rambo, Robert P.; Poole II, Farris L.; Tsutakawa, Susan E.; Jenney Jr, Francis E.; Classen, Scott; Frankel, Kenneth A.; Hopkins, Robert C.; Yang, Sungjae; Scott, Joseph W.; Dillard, Bret D.; Adams, Michael W. W.; Tainer, John A.
Waveguide detection of right-angle-scattered light in flow cytometry
A transparent flow cell is used as an index-guided optical waveguide. A detector for the flow cell but not the liquid stream detects the Right-Angle-Scattered (RAS) Light exiting from one end of the flow cell. The detector(s) could view the trapped RAS light from the flow cell either directly or through intermediate optical light guides. If the light exits one end of the flow cell, then the other end of the flow cell can be given a high-reflectivity coating to approximately double the amount of light collected. This system is more robust in its alignment than the traditional flow cytometry systems which use imaging optics, such as microscope objectives.
Mariella, Jr., Raymond P. (Danville, CA)
Small angle x-ray scattering studies of carbon anodes used in lithium rechargeable batteries.
In ANL laboratories, disordered carbons with predictable surface area and porosity properties have been prepared using inorganic templates containing well defined pore sizes. The carbons have been tested in electrochemical cells as anodes in lithium secondary batteries. They deliver high specific capacity and display excellent performance in terms of the number of cycles run. In situ small angle X-ray scattering (SAXS) during electrochemical cycling was carried out at the Advanced Photon Source, at ANL. In order to monitor the carbon electrode structural changes upon cycling, an electrochemical cell was specially designed to allow for the application of electrical current and the collection of SAXS data at the same time. Results show that upon cycling the structure of the carbon remains unchanged, which is desirable in reversible systems.
Sandi, G.; Carrado, K. A.; Winans, R. E.; Seifert, S.; Johnson, C. S.
A Precision Measurement of the Weak Mixing Angle in Moller Scattering at Low Q^2
The electroweak theory has been probed to a high level of precision at the mass scale of the Z{sup 0} through the joint contributions of LEP at CERN and the SLC at SLAC. The E158 experiment at SLAC complements these results by measuring the weak mixing angle at a Q{sup 2} of 0.026 (GeV/c){sup 2}, far below the weak scale. The experiment utilizes a 48 GeV longitudinally polarized electron beam on unpolarized atomic electrons in a target of liquid hydrogen to measure the parity-violating asymmetry A{sup PV} in Moeller scattering. The tree-level prediction for A{sup PV} is proportional to 1-4 sin{sup 2} {theta}{sub W}. Since sin{sup 2} {theta}{sub W} {approx} 0.25, the effect of radiative corrections is enhanced, allowing the E158 experiment to probe for physics effects beyond the Standard Model at the TeV scale. This work presents the results from the first two physics runs of the experiment, covering data collected in the year 2002. The parity-violating asymmetry A{sup PV} was measured to be A{sup PV} = -158 ppb {+-} 21 ppb (stat) {+-} 17 ppb (sys). The result represents the first demonstration of parity violation in Moeller scattering. The observed value of A{sup PV} corresponds to a measurement of the weak mixing angle of sin{sup 2} {theta}{sub W}{sup eff} = 0.2380 {+-} 0.0016(stat) {+-} 0.0013(sys), which is in good agreement with the theoretical prediction of sin{sup 2} {theta}{sub W}{sup eff} = 0.2385 {+-} 0.0006 (theory).
Jones, G.
New detector array improves neutron count capability at HFIR...
and Ron Maples. Bio-SANS, the Biological Small-Angle Neutron Scattering Instrument at HFIR recently had a detector upgrade that will provide significantly improved performance...
Corrections on energy spectrum and scatterings for fast neutron radiography at NECTAR facility
Neutron spectrum and scattered neutrons caused distortions are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-II in Technische Universit\\"at M\\"unchen (TUM), Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by neutron spectrum, as well as the Point Scattered Function (PScF) simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve images qualities. Good analysis results prove the sounded effects of above two corrections.
Shu-Quan, Liu; Hang, Li; Yu-Bin, Zou; Yuan-Rong, Lu; Zhi-Yu, Guo
SCATMECH: Polarized Light Scattering C++ Class Library ...
... cout tab // Scattering angle (theta) tab // Scattering angle (phi) tab // Principal angle of ...
The effect of the shape function on small-angle scattering analysis by the maximum entropy method
Analysis of small-angle scattering data to obtain a particle size distribution is dependent upon the shape function used to model the scattering. Using a maximum entropy analysis of small-angle scattering data, the effect of shape function selection on obtained size distribution is demonstrated using three different shape functions to describe the same scattering data from each of two steels. The alloys have been revealed by electron microscopy to contain a distribution of randomly oriented and mainly non-interacting, irregular, ellipsoidal precipitates. Comparison is made between the different forms of the shape function. Effect of an incident wavelength distribution is also shown. The importance of testing appropriate shape functions and validating these against other microstructural studies is discussed.
Jemian, P.R. [Argonne National Lab., IL (United States); Allen, A.J. [Univ. of Maryland, College Park, MD (United States). Department of Physics]|[National Inst. of Standards and Technology, Gaithersburg, MD (United States)
The Manuel Lujan, Jr. Neutron Scattering Center LANSCE experiment reports 1989 run cycle
This report contains a listing and description of experiments carried on at the LANSCE neutron scattering facility in the following areas: High Density Powder Diffraction; Neutron Powder Diffractometer, (NPD); Single Crystal Diffractometer, (SCD); Low-Q Diffractometer, (LQD); Surface Profile Analysis Reflectometer, (SPEAR); Filter Difference Spectrometer, (FDS); and Constant-Q Spectrometer.
Hyer, D.K.; DiStravolo, M.A. (comps.)
A slow-neutron-transmission method fro dertermining the hydrogen content of fluorcarbons is described (G.Y.).
Rainwater, L.J.; Havens, W.W. Jr.
Improved Technique of Hydrogen Content Analysis by Slow Neutron Scattering
DOE R&D Accomplishments (OSTI)
A slow-neutron-transmission method fro determining the H content of fluorcarbons is described (G.Y.)
Rainwater, L. J.; Havens, W. W. Jr.
Fourteenth National School on Neutron and X-ray Scattering
either nuclear physics parameters such as the effective delayed neutron fraction, or the so- called several new features in the physics of the ADS that require further development of the theory of neutron / q 3.784= #12;Neutron Fluctuations in Reactors R111 The physical reason for the above
Pennycook, Steve
National School on Neutron and X-ray Scattering
Cooling of isolated neutron stars as a probe of superdense matter physics Alexander Kaminker physics Alexander Kaminker 1. Introduction Microscopic theories of superdense matter in neutron star cores #12;Cooling of isolated neutron stars as a probe of superdense matter physics Alexander Kaminker
Neutron Scattering Society of America Purpose and New Initiatives
's personal copy Dosimetry and spectrometry at accelerator based neutron source for boron neutron capture Institute of Nuclear Physics, 11 Lavrentiev Ave., 630090 Novosibirsk, Russia Federation a r t i c l e i n f Keywords: Epithermal neutrons Accelerator Time-of-flight technique a b s t r a c t An innovative
Design Analyses and Shielding of HFIR Cold Neutron Scattering Instruments
Research reactor geometries and special characteristics present unique dosimetry analysis and measurement issues. The introduction of a cold neutron moderator and the production of cold neutron beams at the Oak Ridge National Laboratory High Flux Isotope Reactor have created the need for modified methods and devices for analyzing and measuring low energy neutron fields (0.01 to 100 meV). These methods include modifications to an MCNPX version to provide modeling of neutron mirror reflection capability. This code has been used to analyze the HFIR cold neutron beams and to design new instrument equipment that will use the beams. Calculations have been compared with time-of-flight measurements performed at the start of the neutron guides and at the end of one of the guides. The results indicate that we have a good tool for analyzing the transport of these low energy beams through neutron mirror and guide systems for distance up to 60 meters from the reactor. (authors)
Gallmeier, F.X.; Selby, D.L.; Winn, B.; Stoica, D.; Jones, A.B.; Crow, L. [Neutron Sciences Directorate, Oak Ridge National Laboratory (United States)
Neutron scattering study of MnSi proving no exchange hole
Neutron scattering experiments have been performed in MnSi below T/sub c/ with the double-axis powder scattering technique using unpolarized neutrons, and also with the polarization analysis technique. The magnetic scattering intensity has not shown any anomaly around q = 0.5 A/sup -1/, in contrast to the previous results of Ziebeck et al. who found a large intensity peak at this momentum transfer. Thus the hypothesis of Ziebeck et al. of observing an Exchange Hole is excluded.
Uemura, Y.J.; Majkrzak, C.F.; Shirane, G.; Ishikawa, Y.
Neutron Scattering Studies of Fundamental Processes in Earth Materials, Final Report
The aim of this work was to use neutron scattering techniques to explore the dynamics and structure of water in rock samples. The dynamics of water in rock at low (residual) saturation are directly related to the transport properties of fluids within the host rock. The structure of water in rock may be related to the elastic behavior of the rock, which in many cases is nonlinear and hysteretic. Neutron scattering techniques allow us to study water in intact rock samples at both the molecular and microstructural scales. Our samples were Berea sandstone, Calico Hills and Prow Pass tuffs from Yucca Mountain, NV, and pure samples of the tuff constituents, specifically mordenite and clinoptilolite. We chose Berea sandstone because its macroscopic elastic behavior is known to be highly unusual, and the microscopic mechanisms producing this behavior are not understood. We chose Yucca Mountain tuff, because the fluid transport properties of the geologic structure at Yucca Mountain, Nevada could be relevant to the performance of a high level nuclear waste repository at that site. Neutron scattering methods have a number of properties that are extremely useful for the study of earth materials. In contrast to X-rays, neutrons have very low absorption cross-sections for most elements so that entire bulk samples of considerable size can be 'illuminated' by the neutron beam. Similarly, samples that are optically opaque can be readily investigated by inelastic neutron scattering techniques. Neutrons are equally sensitive to light atoms as to heavy atoms, and can, for example, readily distinguish between Al and Si, neighboring atoms in the periodic table that are difficult to tell apart by X-ray diffraction. Finally, neutrons are particularly sensitive to hydrogen and thus can be used to study the motions, both vibrational and diffusive, of H-containing molecules in rocks, most notably of course, water. Our studies were primarily studies of guest molecules (in our case, water) in a host material (rock). We used three neutron scattering techniques: quasielastic neutron scattering (QNS), inelastic neutron scattering (INS), and neutron powder diffraction (NPD). We used QNS to measure the translational and rotational diffusional motion of water in rock; INS vibrational spectra allowed us to determine the nature of residual water in a sample (disassociated, chemisorbed, or physisorbed); and NPD measurements may allow us to determine the locations of residual water molecules (and the associated dynamic disorder), and thereby understand the binding of water molecules in our samples.
McCall, K. R.
A High Intensity Neutron Scattering Techniques for Hydrogen ...
Nucleation and Growth Observed by Ultrafast SAXS and WAXS � O10: Effect of Nickel on the Neutron Irradiation Sensitivity of Nuclear Reactor Pressure Vessel�...
Doing Neutron Scattering Science with the Multi-Axis Crystal ...
... at the NIST Center for Neutron Research began commissioning operation on ... and Internal Stress Analysis after High Temperature Corrosion in Power Plants.
Microsoft PowerPoint - Herwig-QuasielasticNeutronScattering.pptx
Ken Herwig Ken Herwig Deputy Director Neutron Facilities Development Division p Oak Ridge National Laboratory J 14 2011 June 14, 2011 OUTLINE * Background - the incoherent...
The Neutron Scattering Society www.neutronscattering.org
Abstract submitted to the XXXIst International Conference on High Energy Physics 24--31 July 2002, Amsterdam, The Netherlands Abstract: 000 Parallel Sessions: 0,0 Leading neutron production in e + p collisions at HERA ZEUS Collaboration Abstract The production of neutrons carrying at least 20% of the proton
Chen, Sow-Hsin
Educational Programs - National School on Neutron & X-ray Scattering
and national laboratories, will include basic tutorials on the principles of scattering theory and the characteristics of the sources, as well as seminars on the application of...
Instruments | Neutron Science | ORNL
NScD Careers NScD Careers Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | Instruments SHARE Instruments at SNS and HFIR SNS Instrument Name HFIR Instrument Name 1B NOMAD - Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS - Backscattering Spectrometer CG-1D IMAGING - Neutron Imaging Prototype Facility 3 SNAP - Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS - General-Purpose Small-Angle Neutron Scattering Diffractometer 4A MR - Magnetism Reflectometer CG-3 Bio-SANS - Biological Small-Angle Neutron Scattering Instrument 4B LR - Liquids Reflectometer CG-4C CTAX - Cold Neutron Triple-Axis Spectrometer 5 CNCS - Cold Neutron Chopper Spectrometer HB-1 PTAX - Polarized Triple-Axis Spectrometer
Pulsed-neutron monochromator
In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.
Mook, H.A. Jr.
Active probing of cloud multiple scattering, optical depth, vertical thickness, and liquid water content using wide-angle imaging LIDAR.
At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60-degree full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer, and, from there, estimate the volume-averaged liquid water content. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Here we present recent WAIL data oti various clouds and discuss the extension of WAIL to full diurnal monitoring by means of an ultra-narrow magneto-optic atomic line filter for daytime measurements.
Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Tellier, L. L. (Larry L.); Ho, Cheng,
Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells |
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
.28.2011]: Neutron Scattering and Full-Spectrum Solar .28.2011]: Neutron Scattering and Full-Spectrum Solar Cells Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells January 28, 2011 - 5:11pm Addthis Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs Oak Ridge National Lab and North Carolina State University scientists are helping to develop medicines that will block the spread of viruses. Using the Bio-SANS instrument at ORNL's High Flux Isotope Reactor, these researchers are studying how viruses change their structure as they move
MCNP benchmarking of an inelastic neutron scattering system for...
carbon signal depends on the transport conditions of neutrons and gamma rays in the soil matrix, which are affected by the soil moisture and bulk density. While variations in the...
Neutron scattering workshop promotes high-pressure research ...
long-term goals in these areas closer to reality, Oak Ridge National Laboratory (ORNL), home of the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor, is hosting...
Determination of hydrogen in niobium by cold neutron prompt gamma ray activation analysis and neutron incoherent scattering
The presence of trace amounts of hydrogen in niobium is believed to have a detrimental effect on the mechanical and superconducting properties. Unfortunately, few techniques are capable of measuring hydrogen at these levels. We have developed two techniques for measuring hydrogen in materials. Cold neutron prompt gamma-ray activation analysis (PGAA) has proven useful for the determination of hydrogen and other elements in a wide variety of materials. Neutron incoherent scattering (NIS), a complementary tool to PGAA, has been used to measure trace hydrogen in titanium. Both techniques were used to study the effects of vacuum heating and chemical polishing on the hydrogen content of superconducting niobium.
R.L. Paul; H.H. Cheu-Maya; G.R. Myneni
Is there an Ay problem in low-energy neutron-proton scattering?
We calculate Ay in neutron-proton scattering for the interactions models WJC-1 and WJC-2 in the Covariant Spectator Theory. We find that the recent 12 MeV measurements performed at TUNL are in better agreement with our results than with the Nijmegen Phase Shift Analysis of 1993, and after reviewing the low-energy data, conclude that there is no Ay problem in low-energy np scattering.
Gross, Franz
Franz Gross; Alfred Stadler
Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).
D. Akimov; A. Bernstein; P. Barbeau; P. Barton; A. Bolozdynya; B. Cabrera-Palmer; F. Cavanna; V. Cianciolo; J. Collar; R. J. Cooper; D. Dean; Y. Efremenko; A. Etenko; N. Fields; M. Foxe; E. Figueroa-Feliciano; N. Fomin; F. Gallmeier; I. Garishvili; M. Gerling; M. Green; G. Greene; A. Hatzikoutelis; R. Henning; R. Hix; D. Hogan; D. Hornback; I. Jovanovic; T. Hossbach; E. Iverson; S. R. Klein; A. Khromov; J. Link; W. Louis; W. Lu; C. Mauger; P. Marleau; D. Markoff; R. D. Martin; P. Mueller; J. Newby; J. Orrell; C. O'Shaughnessy; S. Pentilla; K. Patton; A. W. Poon; D. Radford; D. Reyna; H. Ray; K. Scholberg; V. Sosnovtsev; R. Tayloe; K. Vetter; C. Virtue; J. Wilkerson; J. Yoo; C. H. Yu
particles of her milk using small-angle neutron scattering at ORNL's High Flux Isotope Reactor (HFIR). Casein micelles, a family of related phosphorus-containing proteins, make up...
Neutron scattered dose equivalent to a fetus from proton radiotherapy of the mother
Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando[reg] phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10 000 children.
Mesoloras, Geraldine; Sandison, George A.; Stewart, Robert D.; Farr, Jonathan B.; Hsi, Wen C. [School of Health Sciences, Purdue University, West Lafayette, Indiana 47906 (United States); Midwest Proton Radiotherapy Institute (MPRI), Bloomington, Indiana 47408 (United States)
Use of a high repetition rate neutron generator for in vivo body composition measurements via neutron inelastic scattering
A small D-T neutron generator with a high pulse rate is used for the in vivo measurement of body carbon, oxygen and hydrogen. The core of the neutron generator is a 13 cm-long Zetatron tube pulsed at a rate of 10 kHz delivering 10/sup 3/ to 10/sup 4/ neutrons per pulse. A target-current feedback system regulates the source of the accelerator to assure constant neutron output. Carbon is measured by detecting the 4.44 MeV ..gamma..-rays from inelastic scattering. The short half-life of the 4.44 MeV state of carbon requires detection of the ..gamma..-rays during the 10 ..mu..s neutron pulse. Generators with low pulsing rate were found inappropriate for carbon measurements because of their low duty-cycle (high neutron output during the pulse). In vivo measurements were performed with normal volunteers using a scanning bed facility for a dose less than 25 mrem. This technique offers medical as well as general bulk analysis applications. 8 refs., 5 figs.
Kehayias, J.J.; Ellis, K.J.; Cohn, S.H.; Weinlein, J.H.
Scattering Print Scattering Print When a crystalline sample is illuminated with x-rays, the x-rays are scattered (diffracted) into very specific directions with various intensities. Detectors are used to measure this "diffraction pattern," which is then processed by computers to deduce the arrangement of atoms within the crystal. Hard x-rays have wavelengths comparable to the distance between atoms. Essentially everything we know about the atomic structure of materials is based on results from x-ray and neutron diffraction. From advanced ceramics to catalysts, from semiconductor technology to the frontiers of medicine, and from new magnetic materials and devices to framework compounds used to sequester radioactive waste, crystallography using hard x-ray diffraction techniques at synchrotron radiation facilities plays a crucial role in our ability to understand and control the world in which we live.
The Los Alamos Neutron Scattering Center data acquisition system
The FASTBUS subsystem of the LANSCE data acquisition system consists of a single FASTBUS crate segment with four custom modules and a QPI interface for the VAX. Since experiments at the LANSCE facility always include a time-of-flight parameter for the detected neutron and may optionally include additional position parameters characterizing the event, a time stamp is generated for each event by the Programmable Master Clock (PMC) module. The time and any position information are latched into the Time-Of-Flight buffer (TOF) module. After all events associated with a single neutron burst have been captured in a frame buffer internal to the TOF module, each event is analyzed by the MAPPER module and reduced to a histogram address to increment in the BULKSTORE module. Software access to the histogram is provided through the QPI interface.
Nelson, R.O.; Cort, G.; Gjovig, A.; Goldstone, J.A.; McMillan, D.E.; Ross, J.; Seal, J.; Machen, D.R.
Virtual Compton scattering and neutral pion electroproduction in the resonance region up to the deep inelastic region at backward angles
We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e,e'p)? exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q2=1 GeV2, and for the Q2-dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q2-dependence is smooth. The measured ratio of H(e,e'p)? to H(e,e'p)?0 cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to Real Compton Scattering (RCS) at high energy and large angles, our VCS data at the highest W (1.8-1.9 GeV) show a striking Q2-independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.
Laveissiere, Geraud; Degrande, Natalie; Jaminion, Stephanie; Jutier, Christophe; Todor, Luminita; Di Salvo, Rachele; Van Hoorebeke, L.; Alexa, L.C.; Anderson, Brian; Aniol, Konrad; Arundell, Kathleen; Audit, Gerard; Auerbach, Leonard; Baker, F.; Baylac, Maud; Berthot, J.; Bertin, Pierre; Bertozzi, William; Bimbot, Louis; Boeglin, Werner; Brash, Edward; Breton, Vincent; Breuer, Herbert; Burtin, Etienne; Calarco, John; Cardman, Lawrence; Cavata, Christian; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chen, Jian-Ping; Chudakov, Eugene; Cisbani, Evaristo; Dale, Daniel; De Jager, Cornelis; De Leo, Raffaele; Deur, Alexandre; D'Hose, Nicole; Dodge, Gail; Domingo, John; Elouadrhiri, Latifa; Epstein, Martin; Ewell, Lars; Finn, John; Fissum, Kevin; Fonvieille, Helene; Fournier, Guy; Frois, Bernard; Frullani, Salvatore; Furget, Christophe; Gao, Haiyan; Gao, Juncai; Garibaldi, Franco; Gasparian, Ashot; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Glashausser, Charles; Gomez, Javier; Gorbenko, Viktor; Grenier, Philippe; Guichon, Pierre; Hansen, Jens-Ole; Holmes, Richard; Holtrop, Maurik; Howell, Calvin; Huber, Garth; Hyde, Charles; Incerti, Sebastien; Iodice, Mauro; Jardillier, Johann; Jones, Mark; Kahl, William; Kamalov, Sabit; Kato, Seigo; Katramatou, A.T.; Kelly, James; Kerhoas, Sophie; Ketikyan, Armen; Khayat, Mohammad; Kino, Kouichi; Kox, Serge; Kramer, Laird; Kumar, Krishna; Kumbartzki, Gerfried; Kuss, Michael; Leone, Antonio; LeRose, John; Liang, Meihua; Lindgren, Richard; Liyanage, Nilanga; Lolos, George; Lourie, Robert; Madey, Richard; Maeda, Kazushige; Malov, Sergey; Manley, D.; Marchand, Claude; Marchand, Dominique; Margaziotis, Demetrius; Markowitz, Pete; Marroncle, Jacques; Martino, Jacques; McCormick, Kathy; McIntyre, Justin; Mehrabyan, Surik; Merchez, Fernand; Meziani, Zein-Eddine; Michaels, Robert; Miller, Gerald; Mougey, Jean; Nanda, Sirish; Neyret, Damien; Offermann, Edmond; Papandreou, Zisis; Perdrisat, Charles; Perrino, R.; Petratos, Gerassimos; Platchkov, Stephane; Pomatsalyuk, Roman; Prout, David; Punjabi, Vina; Pussieux, Thierry; Quemener, Gilles; Ransome, Ronald; Ravel, Oliver; Real, Jean-Sebastien; Renard, F.; Roblin, Yves; Rowntree, David; Rutledge, Gary; Rutt, Paul; Saha, Arunava; Saito, Teijiro; Sarty, Adam; Serdarevic, A.; Smith, T.; Smirnov, G.; Soldi, K.; Sorokin, Pavel; Souder, Paul; Suleiman, Riad; Templon, Jeffrey; Terasawa, Tatsuo; Tiator, Lothar; Tieulent, Raphael; Tomasi-Gustaffson, E.; Tsubota, Hiroaki; Ueno, Hiroaki; Ulmer, Paul; Urciuoli, Guido; Van De Vyver, R.; van der Meer, Rob; Vernin, Pascal; Vlahovic, B.; Voskanyan, Hakob; Voutier, Eric; Watson, J.W.; Weinstein, Lawrence; Wijesooriya, Krishni; Wilson, R.; Wojtsekhowski, Bogdan; Zainea, Dan; Zhang, Wei-Ming; Zhao, Jie; Zhou, Z.-L.
We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e, e{sup '}p){gamma} exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q{sup 2}=1 GeV{sup 2} and for the Q{sup 2} dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q{sup 2} dependence is smooth. The measured ratio of H(e, e{sup '}p){gamma} to H(e, e{sup '}p){pi}{sup 0} cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to real Compton scattering (RCS) at high energy and large angles, our VCS data at the highest W (1.8-1.9 GeV) show a striking Q{sup 2} independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.
Laveissiere, G.; Jaminion, S.; Salvo, R. Di; Berthot, J.; Bertin, P. Y.; Breton, V.; Fonvieille, H.; Grenier, P.; Ravel, O.; Roblin, Y.; Smirnov, G. [LPC-Clermont, Universite Blaise Pascal, CNRS/IN2P3, F-63177 Aubiere Cedex (France); Degrande, N.; Hoorebeke, L. van; Vyver, R. van de [University of Gent, B-9000 Gent (Belgium); Jutier, C.; Hyde, C. E. [LPC-Clermont, Universite Blaise Pascal, CNRS/IN2P3, F-63177 Aubiere Cedex (France); Old Dominion University, Norfolk, Virginia 23529 (United States); Todor, L.; Dodge, G. E.; McCormick, K.; Ulmer, P. E. [Old Dominion University, Norfolk, Virginia 23529 (United States)] (and others)
Collocation method for the solution of the neutron transport equation with both symmetric and asymmetric scattering
A collocation method is developed for the solution of the one-dimensional neutron transport equation in slab geometry with both symmetric and polarly asymmetric scattering. For the symmetric scattering case, it is found that the collocation method offers a combination of some of the best characteristics of the finite-element and discrete-ordinates methods. For the asymmetric scattering case, it is found that the computational cost of cross-section data processing under the collocation approach can be significantly less than that associated with the discrete-ordinates approach. A general diffusion equation treating both symmetric and asymmetric scattering is developed and used in a synthetic acceleration algorithm to accelerate the iterative convergence of collocation solutions. It is shown that a certain type of asymmetric scattering can radically alter the asymptotic behavior of the transport solution and is mathematically equivalent within the diffusion approximation to particle transport under the influence of an electric field. The method is easily extended to other geometries and higher dimensions. Applications exist in the areas of neutron transport with highly anisotropic scattering (such as that associated with hydrogenous media), charged-particle transport, and particle transport in controlled-fusion plasmas. 23 figures, 6 tables.
Morel, J.E.
The LANSCE (Los Alamos Neutron Scattering Center) target system
During the summer of 1985, we replaced the WNR T-shaped target/moderator scheme with the LANSCE split-target/flux-trap-moderator design. The intent of this 'LANSCE upgrade' was to increase (to 12) the number of neutron beam lines serviced simultaneously, and to enhance the target area shielding and target system to accept 200 ..mu..A of 800-MeV protons. The four LANSCE moderators consist of three (chilled) water moderators, and a liquid hydrogen (20 K) moderator. The LANSCE target is machinable tungsten.
Russell, G.J.; Robinson, H.; Legate, G.L.; Woods, R.; Whitaker, E.R.; Bridge, A.; Hughes, K.J.
A Liquid Hydrogen Target for Precision Measurement of the Weak Mixing Angle in Moller Scattering at SLAC
A 150 cm long liquid hydrogen target has been built for the SLAC End Station A E158 experiment. The target loop volume is 55 liters, and the maximum target heat load deposited by the electron beam is {approx} 700 W. The liquid hydrogen density fluctuation with full beam current (120 Hz repetition rate, 6 x 10{sup 11} electrons/spill) on target is well below 10{sup -4} level, which fulfills the requirement for a precision measurement of the weak mixing angle in the polarized electron-electron scattering process.
Weisend, John G
Review of the Lujan neutron scattering center: basic energy sciences prereport February 2009
The Lujan Neutron Scattering Center (Lujan Center) at LANSCE is a designated National User Facility for neutron scattering and nuclear physics studies with pulsed beams of moderated neutrons (cold, thermal, and epithermal). As one of five experimental areas at the Los Alamos Neutron Science Center (LANSCE), the Lujan Center hosts engineers, scientists, and students from around the world. The Lujan Center consists of Experimental Room (ER) 1 (ERl) built by the Laboratory in 1977, ER2 built by the Office of Basic Energy Sciences (BES) in 1989, and the Office Building (622) also built by BES in 1989, along with a chem-bio lab, a shop, and other out-buildings. According to a 1996 Memorandum of Agreement (MOA) between the Defense Programs (DP) Office of the National Nuclear Security Agency (NNSA) and the Office of Science (SC, then the Office of Energy Research), the Lujan Center flight paths were transferred from DP to SC, including those in ERI. That MOA was updated in 2001. Under the MOA, NNSA-DP delivers neutron beam to the windows of the target crypt, outside of which BES becomes the 'landlord.' The leveraging nature of the Lujan Center on the LANSCE accelerator is a substantial annual leverage to the $11 M BES operating fund worth approximately $56 M operating cost of the linear accelerator (LINAC)-in beam delivery.
Kinetic energy of hydrogen in. beta. -V sub 2 H studied by neutron Compton scattering
Hydrogen dissolves in nearly all metals in large quantities, occupying interstitial sites which are energetic minima of the hydrogen potential. Experimentally, this potential can be determined by neutron vibrational spectroscopy (NVS) and, recently, by neutron Compton scattering (NCS) i.e. either by a measurement of the excitation energies of the localized hydrogen vibrations or by a measurement of the hydrogen momentum distribution. In this brief communication we report on what we believe is the first NCS experiment on a metal hydride. For the system to be investigated we chose {beta}-V{sub 2}H, an ordered hydride phase with hydrogen on pseudotetragonal octahedral sites. 3 figs., 7 refs.
Hempelmann, R.; Richter, D. (Forschungszentrum Juelich GmbH (Germany, F.R.). Inst. fuer Festkoerperforschung); Price, D.L. (Argonne National Lab., IL (USA))
Dynamic behavior of hydration water in calcium-silicate-hydrate gel: A quasielastic neutron scattering spectroscopy investigation
The translational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel was studied by quasielastic neutron scattering spectroscopy in the temperature range from 280 to 230 K. The stretch exponent ...
Li, Hua
Measurement of the neutron magnetic form factor from inclusive quasielastic scattering of polarized electrons from polarized [sup 3]He
We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized [sup 3]He target. The neutron magnetic form factor [ital G][sup [ital n
Gao, H.; Arrington, J.; Beise, E.J.; Bray, B.; Carr, R.W.; Filippone, B.W.; Lung, A.; McKeown, R.D.; Mueller, B.; Pitt, M.L. (California Institute of Technology, Pasadena, California 91125 (United States)); Jones, C.E. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); DeSchepper, D.; Dodson, G.; Dow, K.; Ent, R.; Farkhondeh, M.; Hansen, J.; Korsch, W.; Kramer, L.H.; Lee, K.; Makins, N.; Milner, R.G.; Tieger, D.R.; Welch, T.P. (Bates Linear Accelerator Center, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Masschusetts 02139 (United States)); Candell, E.; Napolitano, J.; Wojtsekhowski, B.B.; Tripp, C. (Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)); Lorenzon, W. (TRIUMF, Vancouver, British Columbia, V6T 2A3 (Canada))
Dr. Yuri B. Melnichenko | ORNL Neutron Sciences
Scientist: General-Purpose Small-Angle Neutron Scattering Spectrometer (CG-2GP-SANS), HFIR Senior Research Staff Education PhD in Polymer Physics, Institute for Macromolecular...
Neutron scattering from elemental indium, the optical model, and the bound-state potential
Neutron differential elastic-scattering cross sections of elemental indium are measured from 4.5 to 10 MeV at incident-energy intervals of {approx}500 keV. Seventy or more differential values are obtained at each incident energy, distributed between {approx}18{degree} and 160{degree}. These experimental results are combined with lower-energy values previously obtained at this laboratory, and with 11 and 14 MeV results in the literature, to form a comprehensive elastic-scattering database extending from {approx}1.5 to 14 MeV. These data are interpreted in terms of a conventional spherical optical model. The resulting potential is extrapolated to the bound-state regime. It is shown that in the middle of the 50--82 neutron shell, the potential derived from the scattering results adequately describes the binding energies of article states, but does not do well for hole states. The latter shortcoming is attributed to the holes states having occupational probabilities sufficiently different from unity, so that the exclusion principle become a factor, and to the rearrangement of the neutron core. 68 refs.
Chiba, S. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)); Guenther, P.T.; Lawson, R.D.; Smith, A.B. (Argonne National Lab., IL (USA))
Method for improving the angular resolution of a neutron scatter camera
An instrument that will directly image the fast fission neutrons from a special nuclear material source wherein the neutron detection efficiency is increased has been described. Instead of the previous technique that uses a time-of-flight (TOF) between 2 widely spaced fixed planes of neutron detectors to measure scatter neutron kinetic energy, we now use the recoil proton energy deposited in the second of the 2 scatter planes which can now be repositioned either much closer together or further apart. However, by doubling the separation distance between the 2 planes from 20 cm to a distance of 40 cm we improved the angular resolution of the detector from about 12.degree. to about 10.degree.. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6.degree. without adding additional detectors or ancillary electronics. The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular resolution of this new configuration, therefore, is increased at the expanse of detection sensitivity. However, the diminished sensitivity may be acceptable for those applications where the detector is able to interrogate a particular site for an extended period.
Mascarenhas, Nicholas; Marleau, Peter; Gerling, Mark; Cooper, Robert Lee; Mrowka, Stanley; Brennan, James S.
{gamma}Z corrections to forward-angle parity-violating ep scattering
We use dispersion relations to evaluate the {gamma}Z box contribution to parity-violating electron scattering in the forward limit arising from the axial-vector coupling at the electron vertex. The calculation makes full use of the critical constraints from recent JLab data on electroproduction in the resonance region as well as high-energy data from HERA. At the kinematics of the Q{sub weak} experiment, this gives a correction of 0.0047{sub -0.0004}{sup +0.0011} to the standard model value 0.0713(8) of the proton weak charge. While the magnitude of the correction is highly significant, the uncertainty is within the anticipated experimental uncertainty of {+-}0.003.
Sibirtsev, A. [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Blunden, P. G. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2 (Canada); Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Melnitchouk, W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Thomas, A. W. [CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide SA 5005 (Australia)
Small-angle x-ray scattering measurements of the microstructure of liquid helium mixtures adsorbed in aerogel
Small-angle x-ray scattering (SAXS) was used to measure the microstructure of isotopic mixtures of {sup 3}He and {sup 4}He adsorbed into silica aerogels as a function of temperature and {sup 3}He concentration. The SAXS measurements could be well described by the formation of a nearly pure film of {sup 4}He which separates from the bulk mixture onto the aerogel strands and which thickens with decreasing temperature. Previous observations of a superfluid {sup 3}He-rich phase are consistent with superfluidity existing within this film phase. Observed differences between different density aerogels are explained in terms of the depletion of {sup 4}He from the bulk mixture due to film formation.
Lurio, L. B.; Mulders, N.; Paetkau, M.; Chan, M. H. W.; Mochrie, S. G. J. [Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States); Department of Physics, University of Delaware, Newark, Delaware 19716 (United States); Department of Physics and Astronomy, Okanagan College, British Columbia V1Y4X8 (Canada); Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Physics, Yale University, New Haven, Connecticut 06511 (United States)
ORNL Neutron Sciences
ORNL's Neutron Science Future: Integrating Neutron Scattering Across the Laboratory Greg Smith, HFIR Center for Neutron Scattering Upgrade Status and Scientific Opportunities...
Quasielastic neutron scattering of -NH3 and -BH3 rotational dynamics in orthorhombic ammonia borane
Neutrons scattering techniques are ideally suited to directly probe H in materials due to the large incoherent scattering cross-section of hydrogen atom, and have been invaluable in providing direct insight into the local fluctuations and large amplitude motions in AB. Dihydrogen bonding may have a significant affect on materials to be used to store hydrogen for fuel-cell powered applications. We have noticed a trend of low temperature release of H2 in materials composed of hydridic and protonic hydrogen. This phenomenon has caught our attention and motivated our interest to gain more insight into dihydrogen bonding interactions in AB. We present results from a thorough Quasielastic Neutron Scattering (QENS) investigation of diffusive hydrogen motion in NH311BH3 and ND311BH3 to obtain (1) a direct measure of the rotational energy barriers the protonated species and (2) a confirmation of the 3-site jump model for rotational motion. The amplitude of the energy barrier of rotation of BH3 and NH3 determined by QENS are compared to those determined for BD3 and ND3 determined by 2H NMR studies.
Hess, Nancy J.; Hartman, Michael R.; Brown, Craig; Mamontov, Eugene; Karkamkar, Abhijeet J.; Heldebrant, David J.; Daemen, Luke L.; Autrey, Thomas
In-situ small-angle X-ray scattering study of the precipitation behavior in a Fe-25 at.%Co-9 at.%Mo alloy
Fe-Co-Mo alloys show extraordinary mechanical properties which make them potential candidates for various high-performance applications. In the present study, for the first time, the precipitation behavior in a Fe-25 at.%Co-9 at.%Mo alloy was studied by small-angle X-ray scattering using high-energy synchrotron radiation. The specimens were isothermally aged in an in-situ furnace. The small-angle X-ray scattering patterns showed scaling behavior and were evaluated by employing a model function from the literature. This approach provides information about the characteristic length scale and the volume fraction of the precipitates in the alloy.
Zickler, Gerald A. [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Christian Doppler Laboratory for Early Stages of Precipitation, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)], E-mail: firstname.lastname@example.com; Eidenberger, Elisabeth [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Leitner, Harald [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Christian Doppler Laboratory for Early Stages of Precipitation, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Stergar, Erich; Clemens, Helmut [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Staron, Peter; Lippmann, Thomas; Schreyer, Andreas [GKSS Research Center Geesthacht, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany)
Exploration of deeply virtual Compton scattering on the neutron in the Hall A of Jefferson Laboratory
Generalized Parton Distributions (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. Deeply Virtual Compton Scattering (DVCS) is the simplest hard exclusive process involving GPDs. In particular, the DVCS on the neutron is mostly sensitive to E, the less constrained GPD, wich allows to access to the quark angular momentum. The first dedicated DVCS experiment on the neutron ran in the Hall A of Jefferson Lab in fall 2004. The high luminosity of the experiment and the resulting background rate recquired specific devices which are decribed in this document. The analysis methods and the experiment results, leading to preliminary constraints on the GPD E, are presented.
Malek Mazouz
Deeply virtual Compton scattering on longitudinally polarized protons and neutrons at CLAS
This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH{sub 3}) and deuterons (ND{sub 3}) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.
Silvia Niccolai
Structure and dynamics of water adsorbed in carbon nanotubes : a joint neutron scattering and molecular-dynamics study.
The advent of nanocarbons, from single- and multiple-walled nanotubes to nanohorns, avails model studies of confined molecules on the nanoscale. Water encapsulated inside the quasi-one-dimensional channels of these materials is expected to exhibit anomalous behavior due to the unique geometry of nanotubes and the weak interaction between the water molecules and the carbon atoms. We have employed neutron small-to-wide angle diffraction, quasielastic and inelastic scattering in conjunction with molecular-dynamics simulations to characterize the structures and dynamics of water adsorbed in open-ended single- and double-walled nanotubes over a wide range of spatial and temporal scales. We find that a square-ice sheet wrapped next to the inner nanotube wall and a water chain in the interior are the key structural elements of nanotube-confined water/ice. This configuration results in a hydrogen-bond connectivity that markedly differs from that in bulk water. This significantly softened hydrogen-bond network manifests in strong energy shifts of the observed and simulated inter- and intra-molecular vibrations. The very large mean-square displacement of hydrogen atoms observed experimentally and the strong anharmonicity inferred from simulations explain the fluid-like behavior at temperatures far below the freezing point of normal water.
de Souza, N. R.; Kolesnikov, A. I.; Loong, C.-K.; Moravsky, A. P.; Loutfy, R. O.; Burnham, C. J.; Intense Pulsed Neutron Source; MER Corp.; Univ. of Utah
HFIR Experiment Facilities | ORNL Neutron Sciences
Scattering Scattering Neutron Scattering Facilities at HFIR The fully instrumented HFIR will eventually include 15 state-of-the-art neutron scattering instruments, seven of which will be designed exclusively for cold neutron experiments, located in a guide hall south of the reactor building. The currently available instruments and the status of new instruments can be found on the HFIR Instrument Systems pages. Particularly prominent in the cold neutron guide hall are the two small-angle neutron scattering (SANS) instruments, each terminating in a 70-ft-long evacuated cylinder containing a large moveable neutron detector. In addition to the instruments, laboratories are equipped for users to prepare samples. Perhaps the most exciting development at HFIR is the successfully
New thermal neutron scattering files for ENDF/B-VI release 2
At thermal neutron energies, the binding of the scattering nucleus in a solid, liquid, or gas affects the cross section and the distribution of secondary neutrons. These effects are described in the thermal sub-library of Version VI of the Evaluated Nuclear Data Files (ENDF/B-VI) using the File 7 format. In the original release of the ENDF/B-VI library, the data in File 7 were obtained by converting the thermal scattering evaluations of ENDF/B-III to the ENDF-6 format. These original evaluations were prepared at General Atomics (GA) in the late sixties, and they suffer from accuracy limitations imposed by the computers of the day. This report describes new evaluations for six of the thermal moderator materials and six new cold moderator materials. The calculations were made with the LEAPR module of NJOY, which uses methods based on the British code LEAP, together with the original GA physics models, to obtain new ENDF files that are accurate over a wider range of energy and momentum transfer than the existing files. The new materials are H in H{sub 2}O, Be metal, Be in BeO, C in graphite, H in ZrH, Zr in ZrH, liquid ortho-hydrogen, liquid para-hydrogen, liquid ortho-deuterium, liquid para-deuterium liquid methane, and solid methane.
MacFarlane, R.E.
The use of chopper spectrometers for cold-to-epithermal neutron scattering at IPNS
A multi-detector chopper spectrometer enables measurements of the scattering function S(Q,E) to be made over a wide range of momentum and energy transfer (Q,E). The application of pulsed-source chopper spectrometers for inelastic measurements at thermal and epithermal energies (50 meV < E < 1000 meV) is well known. Recently at IPNS, we have extended the energy-transfer region down to about 0.5 meV with a resolution of the order of 150 {mu}eV. It is made possible by utilizing the cold-neutron incident spectrum of the 100 K methane moderator in conjunction with a dual beryllium-body rotor system. Neutron incident energies can be changed efficiently over the 4 to 1000 meV region while maintaining an undisturbed sample environment. We describe the operation of the IPNS chopper spectrometers (HRMECS and LRMECS), the instrumental resolution and the background-suppression performance. The capability of measuring inelastic features from 0.5 to 100 meV with an energy resolution of {Delta}E/E{sub 0} = 2.5% is demonstrated by experimental results of crystal-field excitation spectra of a high-Tc superconductor ErBa{sub 2}Cu{sub 3}O{sub 7}. Preliminary data of quasielastic scattering from a room-temperature molten salt AlCl{sub 3}-EMIC are presented.
Loong, C.K.; Donley, L.I.; Ostrowski, G.E.; Kleb, R.; Hammonds, J.P.; Soderholm, L.; Takahashi, S.
The Manuel Lujan Jr. Neutron Scattering Center (LANSCE) experiment reports 1993 run cycle. Progress report
This year the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) ran an informal user program because the US Department of Energy planned to close LANSCE in FY1994. As a result, an advisory committee recommended that LANSCE scientists and their collaborators complete work in progress. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and a associated Proton Storage Ring (PSR), which can Iter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory (LANL) may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. This year, a total of 127 proposals were submitted. The proposed experiments involved 229 scientists, 57 of whom visited LANSCE to participate in measurements. In addition, 3 (nuclear physics) participating research teams, comprising 44 scientists, carried out experiments at LANSCE. Instrument beam time was again oversubscribed, with 552 total days requested an 473 available for allocation.
Farrer, R.; Longshore, A. [comps.
Development and Validation of Temperature Dependent Thermal Neutron Scattering Laws for Applications and Safety Implications in Generation IV Reactor Designs
The overall obljectives of this project are to critically review the currently used thermal neutron scattering laws for various moderators as a function of temperature, select as well documented and representative set of experimental data sensitive to the neutron spectra to generate a data base of benchmarks, update models and models parameters by introducing new developments in thermalization theory and condensed matter physics into various computational approaches in establishing the scattering laws, benchmark the results against the experimentatl set. In the case of graphite, a validation experiment is performed by observing nutron slowing down as a function of temperatures equal to or greater than room temperature.
Ayman Hawari
FUNDAMENTAL STUDIES OF CO2-COAL INTERACTIONS USING NEUTRON SCATTERING AT CONDITIONS RELEVANT sites CARBON CAPTURE AND STORAGE IN UNMINABLE COAL SEAMS IS IMPORTANT COMPONENT OF A PORTFOLIO OF CO2 AND SORPTION CAPACITY FOR CO2 IN DIFFERENT COAL SEAMS NEEDS: ACHIEVE FUNDAMENTAL UNDERSTANDING OF FLUID
Neutron Scattering Study of Quantum Phase Transitions inIntegral Spin Chains.
Quite a few low-dimensional magnets are quantum-disordered 'spin liquids' with a characteristic gap in the magnetic excitation spectrum. Among these are antiferromagnetic chains of integer quantum spins. Their generic feature are long-lived massive (gapped) excitations (magnons) that are subject to Zeeman splitting in external magnetic fields. The gap in one of the magnon branches decreases with field, driving a soft-mode quantum phase transition. The system then enters a qualitatively new high-field phase. The actual properties at high fields, particularly the spin dynamics, critically depend on the system under consideration. Recent neutron scattering studies of organometallic polymer crystals NDMAP (Haldane spin chains with anisotropy) and NTENP (dimerized S = 1 chains) revealed rich and unique physics.
Zheludev, Andrey I [ORNL
Mass fractal characteristics of silica sonogels as determined by small-angle x-ray scattering and nitrogen adsorption
A sample series of silica sonogels was prepared using different water-tetraethoxysilane molar ratio (r{sub w}) in the gelation step of the process in order to obtain aerogels with different bulk densities after the supercritical drying. The samples were analyzed by means of small-angle x-ray-scattering (SAXS) and nitrogen-adsorption techniques. Wet sonogels exhibit mass fractal structure with fractal dimension D increasing from {approx}2.1 to {approx}2.4 and mass-fractal correlation length {xi} diminishing from {approx}13 nm to {approx}2 nm, as r{sub w} is changed in the nominal range from 66 to 6. The process of obtaining aerogels from sonogels and heat treatment at 500 deg. C, in general, increases the mass-fractal dimension D, diminishes the characteristic length {xi} of the fractal structure, and shortens the fractal range at the micropore side for the formation of a secondary structured particle, apparently evolved from the original wet structure at a high resolution level. The overall mass-fractal dimension D of aerogels was evaluated as {approx}2.4 and {approx}2.5, as determined from SAXS and from pore-size distribution by nitrogen adsorption, respectively. The fine structure of the 'secondary particle' developed in the obtaining of aerogels could be described as a surface-mass fractal, with the correlated surface and mass-fractal dimensions decreasing from {approx}2.4 to {approx}2.0 and from {approx}2.7 to {approx}2.5, respectively, as the aerogel bulk density increases from 0.25 (r{sub w}=66) up to 0.91 g/cm{sup 3} (r{sub w}=6)
Donatti, D.A.; Vollet, D.R.; Ibanez Ruiz, A.; Mesquita, A.; Silva, T.F.P. [Unesp-Universidade Estadual Paulista, IGCE, Departamento de Fisica, P.O. Box 178 CEP, 13500-970 Rio Claro, Sao Paulo (Brazil)
Biology & Medicine Archive Biology & Medicine Archive Research Highlights Biology & Medicine Archive Small-Angle Neutron Scattering Team Finds Structural Differences in Sindbis Virus Particles from Different Host Species (2010) Published Work: "The Structure of Sindbis Virus Produced from Vertebrate and Invertebrate Hosts as Determined by Small-Angle Neutron Scattering" Contact: Flora Meilleur Targeted Drug Delivery Systems Studies of the unique structure of synthetic molecules will help in the development of drugs that can target diseased areas of the body. This researched on dendrimers revealed how molecules function within solutions at different pH levels. (2008) Research in progress. Contact: Wei-Ren Chen "Intelligent" Polymers for Biomedical Technologies
In situ determination of soil carbon pool by inelastic neutron scattering: Comparison with dry combustion
There is a well-documented need for new in situ technologies for elemental analysis of soil, particularly for carbon (C), that overcome the limitations of the currently established chemical method by dry combustion (DC). In this work, we evaluated the concordance between the new INS (inelastic neutron scattering) technology and the DC method. The comparisons were carried out in the high C content (30-40%) organic soils of Willard, Ohio (4 sites), in natural forest in Willard, Ohio (1 site), and in a watershed pasture, with an {approx} 10{sup o} slope, in Coshocton, Ohio (5 sites). In addition to these stationary measurements, the organic soil and the pasture were continuously scanned with the inelastic neutron scattering (INS) system to obtain the transects mean C value. Both types of measurements, INS and DC, registered a decline in the surface density of C along transects in the watershed and in the organic soil. Similarly, both recorded a drop in C in the organic soil of about 0.16%. In the pastureland, declines in C levels of 0.08% and 0.10% were observed, respectively, by DC and INS. Combining the results from the three sites yielded a very satisfactory correlation between the INS- and DC-responses, with a regression coefficient, r{sup 2}, value of about 0.99. This suggests the possibility of establishing a universal regression line for various soil types. In addition, we demonstrated the ability of INS to measure the mean value over transect. In organic soil the mean value of an INS scan agreed, {approx} 0.5%, with the mean values of the DC analysis, whereas large discrepancy between these two was recorded in the pastureland. Overall, the various trends observed in C measurements by INS concurred with those determined by the DC method, so enhancing the confidence in the new INS technology.
Wielopolski, L.; Mitra, S.; Chatterjee, A.; Lal, R.
Most of current computer-generated imagery represents scenes with clear atmospheres, neglecting light scattering effects, and most computer-vision systems have not enjoyed success when deployed in uncontrolled outdoor environments. Nevertheless, scattering ...
Diego Gutierrez; Wojciech Jarosz; Craig Donner; Srinivasa G. Narasimhan
Most computer-generated imagery represents scenes with clear atmospheres, neglecting light scattering effects. But scattering is a fundamental aspect of light transport in a wide range of applications, whether one is simulating it or interpreting it, ...
Diego Gutierrez; Henrik Wann Jensen; Wojciech Jarosz; Craig Donner
Role of Triple Phonon Excitations on Large Angle Quasi-elastic Scattering of {sup 54}Cr+{sup 208}Pb System
We study the large angle quasi-elastic scattering of {sup 54}Cr+{sup 208}Pb system in terms of the full-order coupled-channels formalism. We especially investigate the role of single, double and triple phonon excitations on quasi-elastic scattering cross section as well as quasi-elastic barrier distribution of this system for which the experimental data have been measured. It is shown that the triple phonon excitations both in {sup 54}Cr and {sup 208}Pb nuclei seem to be needed by the present coupled-channels calculations in order to reproduce the experimental data of quasi-elastic cross section and barrier distribution for the {sup 54}Cr+{sup 208}Pb system. We also show that the standard value of the surface diffuseness parameter for the nuclear potential a = 0.63 fm, is preferred by the experimental quasi-elastic scattering data for this system.
Zamrun, Muhammad F. [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); Jurusan Fisika FMIPA, Universitas Haluoleo, Kendari, Sulawesi Tenggara 93232 (Indonesia); Kasim, Hasan Abu [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia)
Neutron Physics Group
... spectrum and fluencies is essential for several ... Neutron Interferometer and Optics Facility performed a ... other neutron scattering facilities depends on ...
Neutron and x-ray scattering studies of the metallurgical condition and residual stresses in Weldalite welds
Weldalite is a lithium-containing aluminum alloy which is being considered for aerospace applications because its favorable strength-to-weight ratio. Successful welding of this alloy depends on the control of the metallurgical condition and residual stresses in the heat affected zone. Neutron and x-ray scattering methods of residual stress measurement were applied to plasma arc welds made in aluminum-lithium alloy test panels as part of an evaluation of materials for use in welded structures. In the course of these studies discrepancies between x-ray and neutron results from the heat affected zone (HAZ) of the weld were found. Texture changes and recovery from the cold work, indicated in peak widths, were found in the HAZ as well. The consideration of x-ray and neutron results leads to the conclusion that there is a change in solute composition which modifies the d-spacings in the HAZ which affects the neutron diffraction determination of residual stresses. The composition changes give the appearance of significant compressive strains in the HAZ. This effect and sharp gradients in the texture give severe anomalies in the neutron measurement of residual stress. The use of combined x-ray and neutron techniques and the solution to the minimizing of the neutron diffraction anomalies are discussed.
Spooner, S. [Oak Ridge National Lab., TN (United States); Pardue, E.B.S. [Technology for Energy Corp., Knoxville, TN (United States)
Fast Lidar and Radar Multiple-Scattering Models. Part I: Small-Angle Scattering Using the Photon Variance�Covariance Method
A fast, approximate method is described for the calculation of the intensity of multiply scattered lidar returns from clouds. At each range gate it characterizes the outgoing photon distribution by its spatial variance, the variance of photon ...
Robin J. Hogan
A Search for non-Newtonian force in a precision measurement of the scattering of slow neutrons in Xenon gas
An experimental search for non-newtonian, gravity-like force in a precision measurement of the scattering of slow neutrons in Xenon gas is proposed. A preliminary experiment with small statistics of 25 hours irradiation time was performed and the observed scattering distribution is consistent with the expectation with no additional forces. A 95% CL limit on the coupling strength for a hypothetical force of 1 nm interaction range was evaluated to be 2*10^-15. The expected sensitivity for a planned high statistics runs is discussed.
Yoshio Kamiya; Misato Tani; Sachio Komamiya; Guinyun Kim; Kyungsuk Kim
''Inelastic Neutron Scattering and Periodic Density Functional Studies of Hydrogen Bonded Structures''
This project is directed at a fundamental understanding of hydrogen bonding, the primary reversible interaction leading to defined geometries, networks and supramolecular aggregates formed by organic molecules. Hydrogen bonding is still not sufficiently well understood that the geometry of such supramolecular aggregates can be predicted. In the approach taken existing quantum chemical methods capable of treating periodic solids have been applied to hydrogen bonded systems of known structure. The equilibrium geometry for the given space group and packing arrangement were computed and compared to that observed. The second derivatives and normal modes of vibration will then be computed and from this inelastic neutron scattering (INS) spectra were computed using the normal mode eigenvectors to compute spectral intensities. Appropriate inclusion of spectrometer line width and shape was made in the simulation and overtones, combinations and phonon wings were be included. These computed spectra were then compared with experimental results obtained for low-temperature polycrystalline samples at INS spectrometers at several facilities. This procedure validates the computational methodology for describing these systems including both static and dynamic aspects of the material. The resulting description can be used to evaluate the relative free energies of two or more proposed structures and so ultimately to be able to predict which structure will be most stable for a given building block.
Bruce S. Hudson
Status report on the analysis of inelastic neutron scattering from carbon, iron, yttrium and lead at 96 MeV
This work is part of an effort to provide more experimental data for the (n,n'x) reaction. The experiments were carried out at The Svedberg Laboratory in Uppsala, Sweden, at the quasi-mono-energetic neutron beam of 96 MeV, before the facility was upgraded in 2004. Using an extended data analysis of data primarily intended for measuring elastic neutron scattering only, it was found to be possible to extract information on the inelastic scattering from several nuclei. In the preliminary data analysis, an iterative forward-folding technique was applied, in which a physically reasonable trial spectrum was folded with the response function of the detector system and the output was compared to the experimental data. As a result, double-differential cross sections and angular distributions of inelastic neutron scattering from 12-C, 56-Fe, 89-Y and 208-Pb could be obtained. In this paper, a status update on the efforts to improve the description of the detector response function is given.
C. Gustavsson; C. Hellesen; S. Pomp; A. �hrn; J. Blomgren; U. Tippawan
Characterization of the Neutron Fields in the Lawrence Livermore National Laboratory (LLNL) Radiation Calibration Laboratory Low Scatter Calibration Facility
In June 2007, the Department of Energy (DOE) revised its rule on Occupational Radiation Protection, Part 10 CFR 835. A significant aspect of the revision was the adoption of the recommendations outlined in International Commission on Radiological Protection (ICRP) Report 60 (ICRP-60), including new radiation weighting factors for neutrons, updated internal dosimetric models, and dose terms consistent with the newer ICRP recommendations. ICRP-60 uses the quantities defined by the International Commission on Radiation Units and Measurements (ICRU) for personnel and area monitoring including the ambient dose equivalent H*(d). A Joint Task Group of ICRU and ICRP has developed various fluence-to-dose conversion coefficients which are published in ICRP-74 for both protection and operational quantities. In February 2008, Lawrence Livermore National Laboratory (LLNL) replaced its old pneumatic transport neutron irradiation system in the Radiation Calibration Laboratory (RCL) Low Scatter Calibration Facility (B255, Room 183A) with a Hopewell Designs irradiator model N40. The exposure tube for the Hopewell system is located close to, but not in exactly the same position as the exposure tube for the pneumatic system. Additionally, the sources for the Hopewell system are stored in Room 183A where, prior to the change, they were stored in a separate room (Room 183C). The new source configuration and revision of the 10 CFR 835 radiation weighting factors necessitate a re-evaluation of the neutron dose rates in B255 Room 183A. This report deals only with the changes in the operational quantities ambient dose equivalent and ambient dose rate equivalent for neutrons as a result of the implementation of the revised 10 CFR 835. In the report, the terms 'neutron dose' and 'neutron dose rate' will be used for convenience for ambient neutron dose equivalent and ambient neutron dose rate equivalent unless otherwise stated.
Radev, R
The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles
In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.
Androic, D; Armstrong, D S; Asaturyan, R; Averett, T D; Bailey, S L; Batigne, G; Beck, D H; Beise, E J; Benesch, J; Benmokhtar, F; Bimbot, L; Birchall, J; Biselli, A; Bosted, P; Breuer, H; Brindza, P; Capuano, C L; Carlini, R D; Carr, R; Chant, N; Chao, Y -C; Clark, R; Coppens, A; Covrig, S D; Cowley, A; Dale, D; Davis, C A; Ellis, C; Falk, W R; Fenker, H; Finn, J M; Forest, T; Franklin, G; Frascaria, R; Furget, C; Gaskell, D; Gericke, M.T.W.; Grames, J; Griffioen, K A; Grimm, K; Guillard, G; Guillon, B; Guler, H; Gustafsson, K; Hannelius, L; Hansknecht, J; Hasty, R D; Hawthorne Allen, A M; Horn, T; Ito, T M; Johnston, K; Jones, M; Kammel, P; Kazimi, R; King, P M; Kolarkar, A; Korkmaz, E; Korsch, W; Kox, S; Kuhn, J; Lachniet, J; Laszewski, R; Lee, L; Lenoble, J; Liatard, E; Liu, J; Lung, A; MacLachlan, G A; Mammei, J; Marchand, D; Martin, J W; Mack, D J; McFarlane, K W; McKee, D W; McKeown, R D; Merchez, F; Mihovilovic, M; Micherdzinska, A; Mkrtchyan, H; Moffit, B; Morlet, M; Muether, M; Musson, J; Nakahara, K; Neveling, R; Niccolai, S; Nilsson, D; Ong, S; Page, S A; Papavassiliou, V; Pate, S F; Phillips, S K; Pillot, P; Pitt, M L; Poelker, M; Porcelli, T A; Quemener, G; Quinn, B P; Ramsay, W D; Rauf, A W; Real, J -S; Ries, T; Roche, J; Roos, P.; Rutledge, G A; Schaub, J; Secrest, J; Seva, T; Simicevic, N; Smith, G R; Spayde, D T; Stepanyan, S; Stutzman, M; Suleiman, R; Tadevosyan, V; Tieulant, R; van de Wiele, J; van Oers, W.T.H.; Versteegen, M; Voutier, E; Vulcan, W F; Wells, S P; Warren, G; Williamson, S E; Woo, R J; Wood, S A; Yan, C; Yun, J
Spallation Neutron Source The Spallation Neutron Source (SNS)
F/gim F/gim Spallation Neutron Source The Spallation Neutron Source (SNS) gives researchers more detailed informa- tion on the structure and dynamics of physical and biological materials than ever before possible. This accelerator- based facility provides the most intense pulsed neutron beams in the world. Scien- tists are able to count scattered neutrons, measure their energies and the angles at which they scatter, and map their final positions. SNS enables measurements of greater sensitivity, higher speed, higher resolution, and in more complex sample environments than have been possible at existing neutron facilities. Future Growth SNS was designed from the outset to accommodate a second target station, effectively doubling the capacity of the
Diffuse Scattering
Diffuse Scattering Diffuse Scattering * Anticipatory (trick) question: If you have an x-ray or neutron detector looking at a small sample volume, which will scatter more x- rays or neutrons into the detector 1 atom 100 atoms or 1000 atoms? X-ray or neutron beam Answer: Depends! Diffuse Scattering Gene E. Ice Materials Science and Technology Division Oak Ridge National Laboratory, USA National School on Neutron and X-ray Scattering ORNL/SNS June 2011 Presentation concentrates year graduate-level course into 1 hour * Skip mathematical complexities * Expose to range of applications * Develop intuition for length scales * Talk like x-ray/neutron scattering guru - Reciprocal space - Debye Temperature - Laue monotonic - Krivoglaz defects of 1st/2nd kinds! Great for cocktail parties or impressing attractive strangers-
National School on Neutron and X-Ray Scattering Held at APS&IPNS
Science and Chemistry Divisions but also from several Collaborative Access Teams (CATS) and the Spallation Neutron Source generously provided their time and expertise. We are...
phase behavior in carbon pores phase behavior in carbon pores Neutrons measure phase behavior in pores at angstrom size Compelling new methods for assessing carbon pores for hydrogen storage in fuel cells Research Contact: Yuri Melnichenko Jan. 2012, Written by Agatha Bardoel Yuri Melnichenko and Lilin He GP-SANS instrument scientist Yuri Melnichenko (left) and postdoctoral associate Lilin He. Researchers have measured the phase behavior of green house gases in pores at the angstrom level, using small-angle neutron scattering (SANS) at the Oak Ridge National Laboratory's High Flux Isotope Reactor. Yuri Melnichenko, an instrument scientist on the General-Purpose Small-Angle Neutron Scattering (GP-SANS) Diffractometer at ORNL's High Flux Isotope Reactor, his postdoctoral associate Lilin He and collaborators
Scattering Length Density Calculator
... For energy dependent cross sections please go to ... The neutron scattering length density is defined ... To calculate scattering length densities enter a ...
Neutron reflecting supermirror structure
An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.
Wood, James L. (Drayton Plains, MI)
An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.
Wood, J.L.
A Survey of Students from the National School on Neutron and X-ray Scattering: Communication Habits and Preferences
Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world. And the SNS is one of the world's most intense pulse neutron beams. Management of these resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD started conducting the National School on Neutron and X-ray Scattering (NXS) in conjunction with the Advanced Photon Source (APS) at Argonne National Laboratory in 2007. This survey was conducted to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites and social media, for communicating with students about neutron science The survey was conducted in two phases using a classic qualitative investigation to confirm language and content followed by a survey designed to quantify issues, assumptions, and working hypotheses. Phase I consisted of a focus group in late June 2010 with students attending NXS. The primary intent of the group was to inform development of an online survey. Phase two consisted of an online survey that was developed and pre-tested in July 2010 and launched on August 9, 2010 and remained in the field until September 9, 2010. The survey achieved an overall response rate of 48% for a total of 157 completions. The objective of this study is to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites, social media, for communicating with students about neutron science.
Bryant, Rebecca [Bryant Research, LLC
Dynamic investigation of gold nanocrystal assembly using in situ grazing-incidence small angle x-ray scattering.
Here we investigate the dynamic self-assembly pathway of ordered gold nanocrystal arrays during the self-assembly of gold nanocrystal micelles, with and without the presence of colloidal silica precursors, using grazing-incidence X-ray scattering performed at a synchrotron source. With silica precursors present, a lattice with rhombohedral symmetry is formed from the partial collapse of a face-centered cubic structure. In the absence of silica, a transient body-centered orthorhombic phase appears, which rapidly collapses into a glassy nanocrystal film. The appearance of face-centered and body-centered structures is consistent with a phase diagram for charged colloidal particles with assembly modulated via Coulomb screening.
Dunphy, D.; Fan, H.; Li, X.; Wang, J.; Brinker, C. J.; X-Ray Science Division; Univ. of New Mexico; SNL
Ray tracing flux calculation for the small and wide angle x-ray scattering diffraction station at the SESAME synchrotron radiation facility
The calculation for the optics of the synchrotron radiation small and wide angle x-ray scattering beamline, currently under construction at SESAME is described. This beamline is based on a cylindrically bent germanium (111) single crystal with an asymmetric cut of 10.5 deg., followed by a 1.2 m long rhodium coated plane mirror bent into a cylindrical form. The focusing properties of bent asymmetrically cut crystals have not yet been studied in depth. The present paper is devoted to study of a particular application of a bent asymmetrically cut crystal using ray tracing simulations with the SHADOW code. These simulations show that photon fluxes of order of 1.09x10{sup 11} photons/s will be available at the experimental focus at 8.79 keV. The focused beam dimensions will be 2.2 mm horizontal full width at half maximum (FWHM) by 0.12 mm vertical (FWHM).
Salah, Wa'el [Synchrotron-light for Experimental Science and Application in the Middle East (SESAME), P.O. Box 7, Allan 19252 (Jordan); Department of Physics, The Hashemite University, Zarqa 13115 (Jordan); Sanchez del Rio, M. [European Synchrotron Radiation Facility, Bp 220, 38043 Grenoble Cedex (France); Hoorani, H. [Synchrotron-light for Experimental Science and Application in the Middle East (SESAME), P.O. Box 7, Allan 19252 (Jordan)
Kinetics of HEX-BCC Transition in a Triblock Copolymer in a Selective Solvent: Time Resolved Small Angle X-ray Scattering Measurements and Model Calculations
Time-resolved small angle x-ray scattering (SAXS) was used to examine the kinetics of the transition from HEX cylinders to BCC spheres at various temperatures in poly(styrene-b- ethylene-co-butylene-b-styrene) (SEBS) in mineral oil, a selective solvent for the middle EB block. Temperature-ramp SAXS and rheology measurements show the HEX to BCC order-order transition (OOT) at ~127 oC and order-disorder transition (ODT) at ~180 oC. We also observed the metastability limit of HEX in BCC with a spinodal temperature, Ts ~ 150 oC. The OOT exhibits 3 stages and occurs via a nucleation and growth mechanism when the final temperature Tf peak into two peaks when the cylinder spacing and modulation wavelength are incommensurate predicted by the model is confirmed by analysis of the SAXS data.
Minghai Li; Yongsheng Liu; Huifen Nie; Rama Bansil; Milos Steinhart
Exploring local atomic arrangements in amorphous and metastable phase change materials with x-ray and neutron total scattering
Very little experimental work has conclusively explored the structural transformation between the amorphous and metastable crystalline phases of phase change chalcogenides. A recent flurry of theoretical work has supported likely mechanisms for the phase transition process in Ge-Sb-Te (GST) compositions and invigorated efforts at probing local atomic arrangements experimentally. The pair distribution function (PDF) formalism of total scattering data provides directly both local structure correlations at low real-space dimensions, and intermediate range order at higher length scales, a distinct advantage for following the relevant phase transition in phase change materials (PCM). A challenge facing the field is the difficulty in distinguishing separate peak contributions to pair correlation functions in amorphous and highly disordered samples. For example, various types of local order have been reported for Ge{sub x}Te{sub 1-x} phases, including both random mixtures and discrete structural units, and both 4-fold and 6-fold coordination around Ge. We describe our efforts in advancing capabilities for extracting and refining differential or partial pair distribution function data sets by combining neutron and x-ray total scattering, with extensions to isotopic substitution and anomalous x-ray scattering. Our results combining neutron and x-ray scattering for the Ge{sub x}Te{sub 1-x} series, for example, clearly distinguish Ge-Te and Te-Te contributions in nearest neighbor correlations. Presenting an additional challenge, phase change materials with fast switching speeds (those arguably of greatest technological interest) have stable bulk crystalline phases and do not readily form glasses until reduced to small dimensions. Thin film samples are inherently difficult to probe with conventional crystallographic methods. We demonstrate successful synchrotron x-ray total scattering experiments for PCM thin films with thicknesses between 100 nm and 1 um and describe how chemical short-range order and local bonding environments vary in amorphous, metastable and crystalline GeSb{sub 2}Te{sub 4} films. Total scattering methods for powders and thin films allow for a direct comparison of PCM properties (crystallization temperature, optical contrast between phases, phase change speed, etc.) with observed local structure and motivate further exploration into the atomic configurations enabling this fascinating class of materials.
Page, Katharine [Los Alamos National Laboratory; Daemen, Luc [Los Alamos National Laboratory; Proffen, Thomas [Los Alamos National Laboratory
Scattering Functions of Yolk-Shell Particles
The single-particle small-angle scattering properties of the yolk-shell particle, a new type of core-shell particle with a mobile core within the hosting shell, are systematically investigated. The Debye spatial autocorrelation function, pair distance distribution function and intraparticle structure factor (form factor) are calculated and compared to the corresponding scattering functions of reference systems of hard sphere and concentric core-shell particles with identical sizes. Based on our theoretical calculations, we find that the broken centrosymmetry, originating from the mobility of the trapped yolk, results in an imaginary scattering amplitude. As a result, it contributes an additional destructive interference term which smears certain features present in the scattering functions of the reference systems. Based on our theoretical models, we present the prospect of jointly using small angle neutron and x-ray scattering techniques to quantitatively determine the structural characteristics of yolk-shell particles.
Li, Xin [ORNL] [ORNL; Liu, Kao-Hsiang [National Taiwan University] [National Taiwan University; Wu, Bin [ORNL] [ORNL; Sanchez-Diaz, Luis E [ORNL] [ORNL; Smith, Gregory Scott [ORNL] [ORNL; Chen, Wei-Ren [ORNL] [ORNL
Spin rotation and birefringence effect for a particle in a high energy storage ring and measurement of the real part of the coherent elastic zero-angle scattering amplitude, electric and magnetic polarizabilities
In the present paper the equations for the spin evolution of a particle in a storage ring are analyzed considering contributions from the tensor electric and magnetic polarizabilities of the particle. Study of spin rotation and birefringence effect for a particle in a high energy storage ring provides for measurement as the real part of the coherent elastic zero-angle scattering amplitude as well as tensor electric and magnetic polarizabilities. We proposed the method for measurement the real part of the elastic coherent zero-angle scattering amplitude of particles and nuclei in a storage ring by the paramagnetic resonance in the periodical in time nuclear pseudoelectric and pseudomagnetic fields.
V. G. Baryshevsky; A. A. Gurinovich
Structural and magnetic properties of transition metal substituted BaFe{sub 2}As{sub 2} compounds studied by x-ray and neutron scattering
The purpose of my dissertation is to understand the structural and magnetic properties of the newly discovered FeAs-based superconductors and the interconnection between superconductivity, antiferromagnetism, and structure. X-ray and neutron scattering techniques are powerful tools to directly observe the structure and magnetism in this system. I used both xray and neutron scattering techniques on di#11;erent transition substituted BaFe2As2 compounds in order to investigate the substitution dependence of structural and magnetic transitions and try to understand the connections between them.
Kim, Min Gyu [Ames Laboratory
Structure of light neutron-rich nuclei and mechanism of elastic proton scattering
Differential cross sections for elastic p{sup 6}He, p{sup 8}Li, and p{sup 9}Li scattering at two energies of 70 and 700 MeV per nucleon were calculated within the Glauber theory of multiple diffractive scattering. Threeparticle wave functions ({alpha}-n-n for {sup 6}He, {alpha}-t-n for {sup 8}Li, and {sup 7}Li-n-n for {sup 9}Li) were used for realistic potentials of intercluster interactions. The sensitivity of elastic scattering to proton-nucleus interaction and to the structure of nuclei was explored. In particular, the dependence of the differential cross section on the contribution of higher order collisions, on scattering on the core and peripheral nucleons, and on the contribution of small wave-function components and their asymptotic behavior was determined. A comparison with available experimental data and with the results of calculations within different formalisms was performed.
Ibraeva, E. T., E-mail: email@example.com [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan); Zhusupov, M. A. [Al-Farabi Kazakh National University (Kazakhstan); Imambekov, O. [National Nuclear Center of the Republic of Kazakhstan, Institute of Nuclear Physics (Kazakhstan)
Time-of-Flight Bragg Scattering from Aligned Stacks of Lipid Bilayers using the Liquids Reflectometer at the Spallation Neutron Source
Time-of-flight (TOF) neutron diffraction experiments on aligned stacks of lipid bilayers using the horizontal Liquids Reflectometer at the Spallation Neutron Source are reported. Specific details are given regarding the instrumental setup, data collection and reduction, phase determination of the structure factors, and reconstruction of the one-dimensional neutron scattering length density (NSLD) profile. The validity of using TOF measurements to determine the one-dimensional NSLD profile is demonstrated by reproducing the results of two well known lipid bilayer structures. The method is then applied to show how an antimicrobial peptide affects membranes with and without cholesterol.
Pan, Jianjun [ORNL; Heberle, Frederick A [ORNL; Carmichael, Justin R [ORNL; Ankner, John Francis [ORNL; Katsaras, John [ORNL
Journal of the Korean Physical Society, Vol. 55, No. 4, October 2009, pp. 13891393 Measurements of the Neutron Scattering Spectrum from 238
scattering, Resonance, Time-of-flight, Depleted uranium, LINAC experiment DOI: 10.3938/jkps.55.1389 I and p = 1.2. Two different thickness depleted uranium, with 0.3% U-235, samples were used the neutron time-of-flight (TOF) method and a 6 Li scintillation detector. Two different thickness depleted
Parity Violation in elastic electron scattering : A first measurment of the parity-violating Asymmetry at Q2 = 0.631 GeV/c2 at Backward Angle.
The goal of Experiment E04-115 (the G0 backward angle measurement) at Jefferson Lab is to investigate the contributions of strange quarks to the fundamental properties of the nucleon. The experiment measures parity-violating asymmetries in elastic electron scattering off hydrogen and quasielastic electron scattering off deuterium at backward angles at Q2 = 0.631 (GeV/c)2 and Q2 = 0.232 (GeV/c)2. The backward angle measurement represents the second phase of the G0 experiment. The first phase, Experiment E00-006 (the G0 forward angle experiment), measured parity-violating asymmetries in elastic electron scattering off hydrogen at forward angles over a Q2 range of 0.1-1.0 (GeV/c)2. The experiments used a polarized electron beam and unpolarized hydrogen and deuterium liquid targets. From these measurements, along with the electromagnetic form factors, one can extract the contribution of the strange quark to the proton's charge and magnetization distributions. This thesis represents a fi
Bailey, Stephanie
Structure of neutron-rich Isotopes {sup 8}Li and {sup 9}Li and allowance for it in elastic scattering
The differential cross sections for elastic proton scattering on the unstable neutron-rich nuclei {sup 8}Li and {sup 9}Li at E = 700 and 60 MeV per nucleon were considered. The {sup 8}Li nucleus was treated on the basis of the three-body {alpha}-t-n model, while the {sup 9}Li nucleus was considered within the {alpha}-t-n and {sup 7}Li-n-n models. The cross sections in question were calculated within Glauber diffraction theory. A comparison of the results with available experimental data made it possible to draw conclusions on the quality of the wave functions and potential used in the calculations.
Ibraeva, E. T., E-mail: email@example.com [National Nuclear Center of the Republic of Kazakhstan, Institute for Nuclear Physics (Kazakhstan); Zhusupov, M. A.; Imambekov, O.; Sagindykov, Sh. Sh. [Al Farabi Kazakh National University (Kazakhstan)
A unified view of coherent and incoherent dihydrogen exchange in transition metal hydrides by nuclear resonance and inelastic neutron scattering
In this paper a unified view of coherent and incoherent dihydrogen exchange in transition metal hydrides by nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) is presented. It is shown that both exchange processes coexist i.e. do not transform into each other although they may dominate the spectra in different temperature ranges. This superposition is the consequence of the incorporation of the tunnel frequency J of the coherent process into the nuclear two-spin hamiltonian of hydrogen pairs which allows to treat the problem using the well known density matrix theory of NMR line-shapes developed by Alexander and Binsch. It is shown that this theory can also be used to predict the line-shapes of the rotational tunneling transitions observed in the INS spectra of transition metal dihydrogen complexes and that both NMR and INS spectra depend on similar parameters.
Limbach, H.H.; Ulrich, S.; Buntkowsky, G. [Freie Univ. Berlin (Germany). Inst. fuer Organische Chemie; Sabo-Etienne, S.; Chaudret, B. [Toulouse-3 Univ., 31 (France). Lab. de Chimie de Coordination du C.N.R.S.; Kubas, G.J.; Eckert, J. [Los Alamos National Lab., NM (United States)
The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments
The OH stretching vibrational spectrum of water was measured in a wide range of temperatures across the triple point, 269 K < T < 296 K, using Inelastic Neutron Scattering (INS). The hydrogen projected density of states and the proton mean kinetic energy, _OH, were determined for the first time within the framework of a harmonic description of the proton dynamics. We found that in the liquid the value of _OH is nearly constant as a function of T, indicating that quantum effects on the OH stretching frequency are weakly dependent on temperature. In the case of ice, ab initio electronic structure calculations, using non-local van der Waals functionals, provided _OH values in agreement with INS experiments. We also found that the ratio of the stretching (_OH) to the total (_exp) kinetic energy, obtained from the present measurements, increases in going from ice, where hydrogen bonding is the strongest, to the liquid at ambient conditions and then to the vapour phase, where hydrogen bonding is the weakest. The same ratio was also derived from the combination of previous deep inelastic neutron scattering data, which does not rely upon the harmonic approximation, and the present measurements. We found that the ratio of stretching to the total kinetic energy shows a minimum in the metastable liquid phase. This finding suggests that the strength of intermolecular interactions increases in the supercooled phase, with respect to that in ice, contrary to the accepted view that supercooled water exhibits weaker hydrogen bonding than ice.
Senesi, Roberto [ORNL; Flammini, Davide [ORNL; Kolesnikov, Alexander I [ORNL; Murray, Eamonn D. [University of California, Davis; Galli, Giulia [University of California, Davis; Andreani, Carla [ORNL
A Measurement of the neutron electric form factor at very large momentum transfer using polaried electrions scattering from a polarized helium-3 target
Knowledge of the electric and magnetic elastic form factors of the nucleon is essential for an understanding of nucleon structure. Of the form factors, the electric form factor of the neutron has been measured over the smallest range in Q{sup 2} and with the lowest precision. Jefferson Lab experiment 02-013 used a novel new polarized {sup 3}He target to nearly double the range of momentum transfer in which the neutron form factor has been studied and to measure it with much higher precision. Polarized electrons were scattered off this target, and both the scattered electron and neutron were detected. G{sup n}{sub E} was measured to be 0.0242 � 0.0020(stat) � 0.0061(sys) and 0.0247 � 0.0029(stat) � 0.0031(sys) at Q{sup 2} = 1.7 and 2.5 GeV{sup 2}, respectively.
Aidan Kelleher
Small-angle x-ray scattering studies of microvoids in amorphous silicon-based semiconductors. Annual subcontract report, 1 February 1992--31 January 1993
This report describes work to provide now details of the microstructure for the size scale from about 1 nm to 30 nm in high-quality a-Si:H and related alloys prepared by current state-of-the-art deposition methods as well as by now and emerging deposition technologies to help determine the role of microvoids and other density fluctuations in controlling the opto-electronic properties. The objectives are to determine whether the presence of microstructure as detected by small-angle X-ray scattering (SAXS) (1) limits the photovoltaic (PV) properties of device-quality a-Si:H; (2) plays a role in determine the photostability of a-Si:H; and (3) is responsible for degradation of the PV properties due to alloying with Ge, C, and other constituents. We collaborated with several groups that can supply relevant systematic sets of samples and the associated opto-electronic data to help address these issues. The project also included developing a method to standardize the procedures, minimize substrate influences, and implement improved data reduction and modeling methodology.
Williamson, D.L.; Jones, S.J.; Chen, Y. [Colorado School of Mines, Golden, CO (United States)
Surface Area and Microporosity of Carbon Aerogels from Gas Adsorption and Small- and Wide-Angle X-ray Scattering Measurements
A carbon aerogel was obtained by carbonization of an organic aerogel prepared by sol-gel polymerization of resorcinol and formaldehyde in water. The carbon aerogel was then CO2 activated at 800 �C to increase its surface area and widen its microporosity. Evolution of these parameters was followed by gas adsorption and small- and wide-angle X-ray scattering (SAXS and WAXS, respectively) with contrast variation by using dry and wet (immersion in benzene and m-xylene) samples. For the original carbon aerogel, the surface area, SSAXS, obtained by SAXS, is larger than that obtained by gas adsorption (Sads). The values become nearly the same as the degree of activation of the carbon aerogel increases. This feature is due to the widening of the narrow microporosity in the carbon aerogel as the degree of activation is increased. In addition, WAXS results show that the short-range spatial correlations into the assemblies of hydrocarbon molecules confined inside the micropores are different from those existing in the liquid phase. 1.
David Fair�n-jim�nez; Francisco Carrasco-mar�n; David Djurado; Fran�oise Bley; Fran�oise Ehrburger-dolle; Carlos Moreno-castilla
Zn-impurity effects on quasiparticle scattering in La2-xSrxCuO4 studied by angle-resolved photoemission spectroscopy
Angle-resolved photoemission measurements were performed on Zn-doped La{sub 2-x}Sr{sub x}CuO{sub 4} to investigate the effects of Zn impurities on the low-energy electronic structure. The Zn-impurity-induced increase in the quasiparticle width in momentum distribution curves (MDCs) is approximately isotropic on the entire Fermi surface and energy independent near the Fermi level (EF). The increase in the MDC width is consistent with the increase in the residual resistivity due to the Zn impurities if we assume the carrier number to be 1-x for x=0.17 and the Zn impurity to be a potential scatterer close to the unitarity limit. For x=0.03, the residual resistivity is found to be higher than that expected from the MDC width, and the effects of antiferromagnetic fluctuations induced around the Zn impurities are discussed. The leading edges of the spectra near ({pi},0) for x=0.17 are shifted toward higher energies relative to E{sub F} with Zn substitution, indicating a reduction in the superconducting gap.
Yoshida, T.
Neutrons in Biology, ORNL
Scattering Sciences Division Oak Ridge National Laboratory Phone: 865.241.2897 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...
Scattering Sciences Division Oak Ridge National Laboratory Phone: 865.576.2779 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...
Dr. Michael Agamalian | ORNL Neutron Sciences
Dr. Michael Agamalian Dr. Michael Agamalian Lead Scientist, Ultra-Small-Angle Neutron Scattering (USANS), SNS Education PhD in Physics, St. Petersburg Nuclear Physics Institute, Russia Description of Research Michael Agamalian and collaborators have made important contributions to the development of the ORNL Bonse-Hart Ultra-Small-Angle Neutron Scattering instrument (USANS). In particular, they adopted the classical X-ray Bonse-Hart technique for neutrons by modifying the Si channel-cut crystal and introducing an additional element, a Cd absorber. This innovation, combined with application of a specialized chemical-mechanical treatment of the diffractive surfaces of the Si channel-cut crystal, has increased the sensitivity of the ORNL USANS instrument by three orders of magnitude. This
The Manuel Lujan, Jr. Neutron Scattering Center (LANSCE) experiment reports 1992 run cycle. Progress report
This year was the fifth in which LANSCE ran a formal user program. A call for proposals was issued before the scheduled run cycles, and experiment proposals were submitted by scientists from universities, industry, and other research facilities around the world. An external program advisory committee, which LANSCE shares with the Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory, examined the proposals and made recommendations. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and an associated Proton Storage Ring (PSR), which can alter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. One hundred sixty-seven proposals were submitted for unclassified research and twelve proposals for research of a programmatic interest to the Laboratory; six experiments in support of the LANSCE research program were accomplished during the discretionary periods. Oversubscription for instrument beam time by a factor of three was evident with 839 total days requested and only 371 available for allocation.
DiStravolo, M.A. [comp.
Neutron time behavior for deuterium neutral beam injection into a hydrogen plasma in ORMAK
Neutrons were produced by D-D interactions when a 28-keV deuterium beam was coinjected into a hydrogen plasma in the Oak Ridge Tokamak (ORMAK). Fokker-Planck calculations, which correctly predict the time behavior of the neutron rate after beam turnon, show that the majority of the neutrons are from injected particles interacting with previously injected deuterons that have scattered to pitch angles of approximately 60 to 90/sup 0/ while slowing down.
England, A. C.; Howe, H. C.; Mihalczo, J. T.; Fowler, R. H.
Introduction to Neutron Spin Echo Spectroscopy
... Nuclear Interaction Neutrons are scattered by the nuclei. Scattering power varies �randomly� from isotope to isotope. ... segment dynamics hydro gels ...
Chemical and Engineering Materials | Neutron Science | ORNL
Chemical and Engineering Materials Chemical and Engineering Materials SHARE Chemical and Engineering Materials Neutron-based research at SNS and HFIR in Chemical and Engineering Materials strives to understand the structure and dynamics of chemical systems and novel engineering materials. The user community takes advantage of capabilities of neutron scattering for measurements over wide ranges of experimental and operating conditions, including studies of chemical and physical changes in situ. User experiments with diffraction, small-angle scattering, inelastic and quasi-elastic scattering, and neutron imaging instruments address a range of problems in chemistry and in engineering materials research. Current areas of research supported within Chemical and Engineering Materials include: The structure and dynamics of electrical energy storage materials
Science Education Programs | Neutron Science | ORNL
What are Neutrons Why Research with Neutrons Graduate & Post-doctoral Programs Student & Teacher Programs Science Forum Neutron Scattering Tutorials Kids' Corner News and Awards...
An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.
Dr. George Wignall | ORNL Neutron Sciences
Dr. George D. Wignall Dr. George D. Wignall Consultant: General-Purpose SANS Instrument (CG-2), HFIR Education Ph.D. in Physics, Sheffield University, England Description of Research Dr. Wignall uses small-angle neutron scattering (SANS) to study the structure of homo-polymers, block-copolymers and polymer blends, using deuterium labeling techniques to "color" polymer molecules and make them "visible" in the condensed state. He makes SANS techniques and instrumentation available to the scientific community through the operation of user-friendly facilities. Selected Publications (from over 240) Y. B. Melnichenko and G. D. Wignall, "Small Angle Neutron Scattering in Materials Science: Recent Practical Applications," Journal of Applied Physics 102 021102 (2007)
Neutrons for Materials Science and Engineering - ASM Oak Ridge...
of NST2 Attendees Click for full Size Image Welcome Overview - Michelle Buchanon Fundamentals of Neutron Scattering Research - Ian Anderson Neutron Scattering on Magnetic...
Analytical Calculation of the Neutrons Spectrum for Direct Measurement of N-N Scattering at Pulsed Reactor Yaguar
Analytical calculation of a single neutron detector counts per YAGUAR reactor pulse is presented and comparison with coincidence scheme is given.
V. K. Ignatovich
Dynamics and Neutron Scattering
... energy window ... if there is more than one isotope and/or nonzero nuclear ... Comparisons with theory and/or computer simulations are commonly ...
Neutron Scattering and Dynamics
... "Molecule" H2O (N2)0.8(O2)0.2 Al Cd sigma_s barn 168.3 20.1 1.5 6.5 ... 31 Collective dynamics Animation courtesy of A. Zheludev (ORNL) ...
Neutron Scattering Conferences
8-12, 2013 International Workshop: Powder & Electron Crystallography Location Patras, Greece Contact Partha Pratim Das Email firstname.lastname@example.com URL http:crystallographypatras.wor...
Chemical & EngChemical/Engineering Materials Division | Neutron Science |
Chemical and Engineering Materials Division Chemical and Engineering Materials Division SHARE Chemical and Engineering Materials Division CEMD Director Mike Simonson The Chemical and Engineering Materials Division (CEMD) supports neutron-based research at SNS and HFIR in understanding the structure and dynamics of chemical systems and novel engineering materials. The user community takes advantage of division-supported capabilities of neutron scattering for measurements over wide ranges of experimental and operating conditions, including studies of chemical and physical changes in situ. User experiments with diffraction, small-angle scattering, inelastic and quasielastic scattering, and neutron imaging instruments address a range of problems in chemistry and in engineering materials research. Current areas of research supported by the division include the structure
The performance of the small-angle diffractometer, SAND at IPNS.
The time-of-flight small-angle diffractometer SAND has been serving the scientific user community since 1996. One notable feature of SAND is its capability to measure the scattered intensity in a wide Q (4{pi}sin{theta}/{lambda}, where 2{theta} is the scattering angle and {lambda} is the wavelength of the neutrons) range of 0.0035 to 0.5 {angstrom}{sup {minus}1} in a single measurement. The optical alignment system makes it easy to set up the instrument and the sample. The cryogenically cooled MgO filter reduces the fast neutrons over two orders of magnitude, while still transmitting over 70% of the cold neutrons. A drum chopper running at 15 Hz suppresses the delayed neutron background. SAND has a variety of ancillary equipment to control the sample environment. In this paper we describe the features of the SAND instrument, compare its data on a few standard samples with those measured at well established centers in the world, and display two scientific examples which take advantage of measuring data in a wide Q-range in a single measurement. With a new set of tight collimators the Q{sub min} can be lowered to 0.002 {angstrom}{sup {minus}1} and the presently installed high-angle bank of detectors will extend the Q{sub max} to 2 {angstrom}{sup {minus}1}.
Thiyagarajan, P.
Dr. J. K. (Jinkui) Zhao - ORNL Neutron Sciences
Dr. J.K. (Jinkui) Zhao Dr. J.K. (Jinkui) Zhao Research Staff Dr. Zhao is a research staff in the Neutron Facility Development Division at the Spallation Neutron Source. He has broad interests in many areas ranging from biophysics to neutrons scattering techniques. He was the lead scientist for Extended Q-Range Small-Angle Neutron Scattering Diffractometer (EQ-SANS) instrument during its design, construction and commissioning phases. Resources Software by J.K. Zhao EQ-SANS design documentation Selected Publications Metabolic Scaling in Biology Zhao, Jinkui. "A common origin for 3/4- and 2/3-power rules in metabolic scaling" Submitted Zhao, Jinkui. "Plants' metabolism and metabolic scaling" Submitted Zhao, Jinkui. "Tree growth model" In preparation Biomolecular Structures
Test of the consistency of various linearized semiclassical initial value time correlation functions in application to inelastic neutron scattering from liquid para-hydrogen
The linearized approximation to the semiclassical initial value representation (LSC-IVR) is used to calculate time correlation functions relevant to the incoherent dynamic structure factor for inelastic neutron scattering from liquid para-hydrogen at 14 K. Various time correlations functions were used which, if evaluated exactly, would give identical results, but they do not because the LSC-IVR is approximate. Some of the correlation functions involve only linear operators, and others involve non-linear operators. The consistency of the results obtained with the various time correlation functions thus provides a useful test of the accuracy of the LSC-IVR approximation and its ability to treat correlation functions involving both linear and nonlinear operators in realistic anharmonic systems. The good agreement of the results obtained from different correlation functions, their excellent behavior in the spectral moment tests based on the exact moment constraints, and their semi-quantitative agreement with the inelastic neutron scattering experimental data all suggest that the LSC-IVR is indeed a good short-time approximation for quantum mechanical correlation functions.
Miller, William; Liu, Jian; Miller, William H.
Procurement - ORNL Neutron Sciences
for the acquisition of goods and services for neutron scattering operations at SNS and HFIR. If you're interested in conducting business with the Neutron Sciences Directorate or...
Proceedings of the Oak Ridge National Laboratory/Brookhaven National Laboratory workshop on neutron scattering instrumentation at high-flux reactors
For the first three decades following World War II, the US, which pioneered the field of neutron scattering research, enjoyed uncontested leadership in the field. By the mid-1970's, other countries, most notably through the West European consortium at Institut Laue-Langevin (ILL) in Grenoble, France, had begun funding neutron scattering on a scale unmatched in this country. By the early 1980's, observers charged with defining US scientific priorities began to stress the need for upgrading and expansion of US research reactor facilities. The conceptual design of the ANS facility is now well under way, and line-item funding for more advanced design is being sought for FY 1992. This should lead to a construction request in FY 1994 and start-up in FY 1999, assuming an optimal funding profile. While it may be too early to finalize designs for instruments whose construction is nearly a decade removed, it is imperative that we begin to develop the necessary concepts to ensure state-of-the-art instrumentation for the ANS. It is in this context that this Instrumentation Workshop was planned. The workshop touched upon many ideas that must be considered for the ANS, and as anticipated, several of the discussions and findings were relevant to the planning of the HFBR Upgrade. In addition, this report recognizes numerous opportunities for further breakthroughs on neutron instrumentation in areas such as improved detection schemes (including better tailored scintillation materials and image plates, and increased speed in both detection and data handling), in-beam monitors, transmission white beam polarizers, multilayers and supermirrors, and more. Each individual report has been cataloged separately.
McBee, M.R. (ed.); Axe, J.D.; Hayter, J.B.
Education | ORNL Neutron Sciences
Matter Physics Neutron Scattering in Quantum Condensed Matter Physics flyer The first cyber enabled collaborative graduate course was launched in Fall semester 2012. It addresses...
Neutron Activation Calculator
... and incoherent scattering cross sections). Source neutrons (Ang, meV or m/s), Density (g/cm 3 or lattice), Thickness (cm). ...
Materials Division Oak Ridge National Laboratory Phone: 865.241.5176 SNS Logo HFIR Logo General Information The unique potential of neutron scattering in structural...
POLARIZATION OF Li$sup 7$(p,n)Be$sup 7$ NEUTRONS
The polarization of neutrons emitted from the Li/sup 7/(p,n)Be/sup 7/ reaction at an angle of 50 deg was measured for neutron energies between 0.7 and 1.5 Mev. The polarization was deduced from the right-left asymmetry in the scattering of these neutrons from liquid oxygen. The results indicate that the polarization is close to --0.3, independent of hombarding energy. One measurement for neutrons emitted at 30 deg yields a polarization only slightly smaller than for neutrons emitted at 50 deg for the same proton energy. The total neutron cross section of oxygen was remeasured for neutron energies between 0.7 and 1.4 Mev. (auth)
Striebel, H.R.; Darden, S.E.; Haeberli, W.
Relative measurements of the cross section for scattering of neutrons by protons have been made at 10 MeV neutron energy for center-of-mass neutron scattering angles from 60' to 180'. The measurements were made using the Ohio University Accelerator Laboratory's tandem Van de Graaff accelerator with the D(d,n) reaction as the neutron source. The data are in good agreement with predictions from the phase shift analyses of Arndt, the groups of Nijmegen and Bonn, and the ENDF/B-V evaluation. The ENDF/B-VI evaluation does not appear to have the same angular dependence as the data. KEYWORDS: hydrogen cross section, neutron cross section standard, hydrogen angular distribution standard
Boukharouba, N.; Bateman, F. B. (Fred B.); Brient, C. E.; Carlson, A. D.; Grimes, S. M.; Massey, T. N.; Haight, Robert C.; Carlson, Allan D.; Wasson, O. A.
Neutron Imaging of Hydrogen in Steels
Symposium, Applied Neutron Scattering in Engineering and Materials Science Research. Presentation Title, Neutron Imaging of Hydrogen in Steels. Author(s)�...
Data Management Practices | ORNL Neutron Sciences
to data generated from neutron scattering experiments at the High Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS). Any changes to these guidelines will be...
Directional Detection of Fast Neutrons Using a Time Projection Chamber
Spontaneous fission in Special Nuclear Material (SNM) such as plutonium and highly enriched uranium (HEU) results in the emission of neutrons with energies in the MeV range (hereafter 'fast neutrons'). These fast neutrons are largely unaffected by the few centimeters of intervening high-Z material that would suffice for attenuating most emitted gamma rays, while tens of centimeters of hydrogenous materials are required to achieve substantial attenuation of neutron fluxes from SNM. Neutron detectors are therefore an important complement to gamma-ray detectors in SNM search and monitoring applications. The rate at which SNM emits fast neutrons varies from about 2 per kilogram per second for typical HEU to some 60,000 per kilogram per second for metallic weapons grade plutonium. These rates can be compared with typical sea-level (cosmogenic) neutron backgrounds of roughly 5 per second per square meter per steradian in the relevant energy range [1]. The fact that the backgrounds are largely isotropic makes directional neutron detection especially attractive for SNM detection. The ability to detect, localize, and ultimately identify fast neutron sources at standoff will ultimately be limited by this background rate. Fast neutrons are particularly well suited to standoff detection and localization of SNM or other fast neutrons sources. Fast neutrons have attenuation lengths of about 60 meters in air, and retain considerable information about their source direction even after one or two scatters. Knowledge of the incoming direction of a fast neutron, from SNM or otherwise, has the potential to significantly improve signal to background in a variety of applications, since the background arriving from any one direction is a small fraction of the total background. Imaging or directional information therefore allows for source detection at a larger standoff distance or with shorter dwell times compared to nondirectional detectors, provided high detection efficiency can be maintained. Directional detection of neutrons has been previously considered for applications such as controlled fusion neutron imaging [2], nuclear fuel safety research [3], imaging of solar neutrons and SNM [4], and in nuclear science [5]. The use of scintillating crystals and fibers has been proposed for directional neutron detection [6]. Recently, a neutron scatter camera has been designed, constructed, and tested for imaging of fast neutrons, characteristic for SNM material fission [7]. The neutron scatter camera relies on the measurement of the proton recoil angle and proton energy by time of flight between two segmented solid-state detectors. A single-measurement result from the neutron scatter camera is a ring containing the possible incident neutron direction. Here we describe the development and commissioning of a directional neutron detection system based on a time projection chamber (TPC) detector. The TPC, which has been widely used in particle and nuclear physics research for several decades, provides a convenient means of measuring the full 3D trajectory, specific ionization (i.e particle type) and energy of charged particles. For this application, we observe recoil protons produced by fast neutron scatters on protons in hydrogen or methane gas. Gas pressures of a few ATM provide reasonable neutron interaction/scattering rates.
Bowden, N; Heffner, M; Carosi, G; Carter, D; Foxe, M; Jovanovic, I
SNS Instrument System Beam Lines | ORNL Neutron Sciences
SNS Instrument Beam Lines SNS Instrument Beam Lines This diagram shows the beam lines designated for currently funded instruments. Clicking on an instrument description will take you to the page for that instrument. Clicking anywhere else on the image will open a full-size, printable PDF file. SNS Instrument Layout Backscattering Spectrometer (BASIS) Disordered Materials Diffractometer (NOMAD) Wide Angular-Range Chopper Spectrometer (ARCS) Fine-Resolution Fermi Chopper Spectrometer (SEQUOIA) Coming Soon - Vibrational Spectrometer (VISION) Neutron Spin Echo (NSE) Hybrid Spectrometer (HYSPEC) Fundamental Neutron Physics Beamline (FNPB) Single Crystal Diffractometer (TOPAZ) Versatile Neutron Imaging Instrument (VENUS) Macromolecular Diffractometer (MaNDi) Powder Diffractometer (POWGEN3) Engineering Diffractometer (VULCAN) Extended Q-Range Small Angle Neutron Diffractometer (EQ-SANS) Cold Neutron Chopper Spectrometer (CNCS) Liquids (horizontal surface) Reflectometer (LR) Magnetic Advanced Grazing InCidence Spectrometer (MAGICS) High Pressure Diffractometer (SNAP) Coming Soon - Elastic Diffuse Scattering Spectrometer (CORELLI)
Data Plots of Run I - III Results from SLAC E-158: A precision Measurement of the Weak Mixing Angle in Moller Scattering
Three physics runs were made in 2002 and 2003 by E-158. As a result, the E-158 Collaboration announced that it had made "the first observation of Parity Violation in electron-electron (Moller) scattering). This precise Parity Violation measurement gives the best determination of the electron's weak charge at low energy (low momentum transfer between interacting particles). E158's measurement tests the predicted running (or evolution) of this weak charge with energy, and searches for new phenomena at TeV energy scales (one thousand times the proton-mass energy scale).[Copied from the experiment's public home page at http://www-project slac.stanford.edu/3158/Default.htm] See also the E158 page for collaborators at http://www.slac.stanford.edu/exp/e158/. Both websites provide data and detailed information.
Grazing Incidence Small-Angle X-Ray Scattering Studies of the Synthesis and Growth of CdS Quantum Dots from Constituent Atoms in SiO2 Matrix
Grazing incidence small angle X-ray scattering was applied to study the synthesis and growth of CdS quantum dots (QDs) from Cd and S atoms implanted in SiO{sub 2}. For a dose of 10{sup 17}/cm{sup 2}, the partial synthesis of CdS QDs occurred already during implantation, with only moderate size increase upon subsequent annealing up to T{sub a} = 1073 K. The dynamics of QD synthesis and growth were considerably different for just two times lower dose, where synthesis started only if the implanted samples were annealed at T{sub a} = 773 K or higher, with a strong increase of the size of QDs upon annealing at higher T{sub a}. The results suggest that high-dose implantation followed by low-temperature annealing could lead to better defined sizes and narrower size distributions of QDs.
Desnica, U. V. [R. Boskovic Institute, Zagreb, Croatia; Dubcek, P. [R. Boskovic Institute, Zagreb, Croatia; Desnica-Frankovic, I. D. [R. Boskovic Institute, Zagreb, Croatia; Buljan, M. [R. Boskovic Institute, Zagreb, Croatia; Bernstorff, S. [Sincrotrone Trieste, Basovizza, Italy; White, Clark W [ORNL
A system for differential neutron scattering experiments in the energy range from 0.5 to 20 MeV
piece of depleted uranium was used to attenuate the intense gamma flash. With the sample placed for the experiment. To eliminate gamma flash associated recovery issues, 2.54 cm (1 in.) of depleted uranium, the neutron flux was measured through a one inch thick piece of depleted uranium. By a simple calculation
Level crossings and zero-field splitting in the {Cr8}-cubane spin-cluster studied using inelastic neutron scattering and magnetization
Inelastic neutron scattering (INS) in variable magnetic field and high-field magnetization measurements in the millikelvin temperature range were performed to gain insight into the low-energy magnetic excitation spectrum and the field-induced level crossings in the molecular spin cluster {Cr8}-cubane. These complementary techniques provide consistent estimates of the lowest level-crossing field. The overall features of the experimental data are explained using an isotropic Heisenberg model, based on three distinct exchange interactions linking the eight CrIII paramagnetic centers (spins s = 3/2), that is supplemented with a relatively large molecular magnetic anisotropy term for the lowest S = 1 multiplet. It is noted that the existence of the anisotropy is clearly evident from the magnetic field dependence of the excitations in the INS measurements, while the magnetization measurements are not sensitive to its effects.
Vaknin, D. [Ames Laboratory; Garlea, Vasile O [ORNL; Demmel, F. [ISIS Facility, Rutherford Appleton Laboratory; Mamontov, Eugene [ORNL; Nojiri, H [Institute for Materials Research, Tohoku University, Sendai, Japan; Martin, Catalin [Florida State University; Chiorescu, Irinel [Florida State University; Qiu, Y. [National Institute of Standards and Technology (NIST); Luban, M. [Ames Laboratory; Kogerler, P. [Ames Laboratory; Fielden, J. [Ames Laboratory; Engelhardt, L [Francis Marion University, Florence, South Sarolina; Rainey, C [Francis Marion University, Florence, South Sarolina
Dzyaloshinsky-Moriya interaction and long life time of the spin state in the Cu$_3$ triangular spin cluster by inelastic neutron scattering measurements
Inelastic neutron scattering (INS) experiments have been performed on the Cu$_3$ triangular molecular nanomagnet using powder samples. In the medium resolution INS spectrum measured, there are two peaks at $\\hbar\\omega=0.5$ and 0.6 meV. Comparing the observed $Q$ dependences of these peaks with calculations, these two INS peaks originate from the Cu$_3$ cluster. From the observed peak position, width, and intensity, we have determined the optimum parameters of the spin Hamiltonian consisted of the antiferromagnetic exchange and the Dzyaloshinsky-Moriya interactions, which can also reproduce the magnetic susceptibility measurement. In addition, we have directly observed that the ground state quartet is split into two doublets with the energy separation of 0.103 meV using high-resolution neutron spectroscopy, which exactly corresponds to that expected from the optimum parameters obtained from the medium resolution xperiment. The temperature dependences of the integrated intensities of the 0.5 and 0.6 meV peaks are well reproduced by the Boltzmann distribution of the energy levels of the model Hamiltonian below 10 K. Furthermore, the inelastic peaks were visible even at very high temperatures as 50 K. This indicates extraordinary weak coupling between phonons (or any other perturbations) and spin states in the Cu$_3$ cluster, compared to the other known molecular nanomagnets.
Kazuki Iida; Yiming Qiu; Taku J Sato
Search for the First-Order Liquid-to-Liquid Phase Transition in Low-Temperature Confined Water by Neutron Scattering
It has been conjectured that a 1st order liquid-to-liquid (L-L) phase transition (LLPT) between high density liquid (HDL) and low density liquid (LDL) in supercooled water may exist, as a thermodynamic extension to the liquid phase of the 1st order transition established between the two bulk solid phases of amorphous ice, the high density amorphous ice (HDA) and the low density amorphous ice (LDA). In this paper, we first recall our previous attempts to establish the existence of the 1st order L-L phase transition through the use of two neutron scattering techniques: a constant Q elastic diffraction study of isobaric temperature scan of the D2O density, namely, the equation of state (EOS) measurements. A pronounced density hysteresis phenomenon in the temperature scan of the density above P = 1500 bar is observed which gives a plausible evidence of crossing the 1st order L-L phase transition line above this pressure; an incoherent quasi-elastic scattering measurements of temperature-dependence of the alpha-relaxation time of H2O at a series of pressures, namely, the study of the Fragile-to-Strong dynamic crossover (FSC) phenomenon as a function of pressure which we interpreted as the results of crossing the Widom line in the one-phase region. In this new experiment, we used incoherent inelastic neutron scattering (INS) to measure the density of states (DOS) of H atoms in H2O molecules in confined water as function of temperature and pressure, through which we may be able to follow the emergence of the LDL and HDL phases at supercooled temperature and high pressures. We here report for the first time the differences of librational and translational DOSs between the hypothetical HDL and LDL phases, which are similar to the corresponding differences between the well-established HDA and LDA ices. This is plausible evidence that the HDL and LDL phases are the thermodynamic extensions of the corresponding amorphous solid water HDA and LDA ices.
Chen, Sow-Hsin [Massachusetts Institute of Technology (MIT); Wang, Zhe [Massachusetts Institute of Technology (MIT); Kolesnikov, Alexander I [ORNL; Zhang, Yang [ORNL; Liu, Kao-Hsiang [National Taiwan University
Clifford G. Shull, Neutron Diffraction, Hydrogen Atoms, and Neutron
Office of Scientific and Technical Information (OSTI)
Clifford Shull, Neutron Diffraction, and Neutron Scattering Clifford Shull, Neutron Diffraction, and Neutron Scattering Resources with Additional Information Clifford G. Shull was awarded the 1994 Nobel Prize in Physics "for the development of the neutron diffraction technique". 'Professor Shull's prize was awarded for his pioneering work in neutron scattering, a technique that reveals where atoms are within a material like ricocheting bullets reveal where obstacles are in the dark. Clifford Shull Photo Courtesy of Oak Ridge National Laboratory When a beam of neutrons is directed at a given material, the neutrons bounce off, or are scattered by, atoms in the sample being investigated. The neutrons' directions change, depending on the location of the atoms they hit, and a diffraction pattern of the atoms' positions can then be obtained.
The physics of photons and neutrons with applications of deuterium labeling methods to polymers
Over the past decade small-angle neutron scattering (SANS), has found numerous applications in the fields of biology, polymer science, physical chemistry, materials science, metallurgy, colloids, and solid state physics. A number of excellent references are available which contain basic neutron scattering theory though these text books reflect the origins of the technique and the examples are largely drawn from physics e.g., single crystals, simple liquids, monatomic gases, liquid metals, magnetic materials, etc. in view of the large numbers of nonspecialists who are increasingly using neutron scattering, the need has become apparent for presentations which can provide rapid access to the method without unnecessary detail and mathematical rigor. This article is meant to serve as a general introduction to the symposium ''Scattering Deformation and Fracture in Polymers,'' and is intended to aid potential users who have a general scientific background, but no specialist knowledge of scattering, to apply the technique to provide new information in areas of their own particular interests. In view of space limitations, the general theory will be given in the case for neutron scattering and analogies and differences with photon scattering (x-rays) will be pointed out at the appropriate point. 90 refs., 6 figs.
Wignall, G.D.
Biology and Soft Matter Division - ORNL Neutron Sciences
Home › Neutron Sciences Directorate › Biology and Soft Matter Division Home › Neutron Sciences Directorate › Biology and Soft Matter Division Biology and Soft Matter Division Paul Langan, BSMD Director BSMD Director Paul Langan. The Biology and Soft Matter Division (BSMD) operates an external user program for biological and soft matter research using neutron techniques at SNS and HFIR. Division personnel enable the research initiated by external users by acting as instrument responsible scientists and local contacts on a range of different beam lines. BSMD works closely with the Center for Structural Molecular Biology. Diffraction, small-angle scattering, and reflectometry are ideal methods for studying structure and organization from the atomic to the micron length scales, and neutron spectroscopic methods characterize self and
Capabilities of the ARCS Instrument - ORNL Neutron Sciences
Capabilities of the ARCS Instrument Capabilities of the ARCS Instrument ARCS Overview The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of 3He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and
Neutron Physics at NIST 8th UCN Workshop
The Neutron Scattering Society of America www.neutronscattering.org Press Release, February 4, 2008 The Neutron Scattering Society of America is pleased to announce the 2008 recipients of its 3 major prizes. The Neutron Scattering Society of America (NSSA) established the Clifford G. Shull Prize in Neutron Science
Titov, Anatoly
A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.
Wigner, E.P.
Hazard Analysis for the High Power Accelerator Production of Tritium (APT) Experiments at the Los Alamos Neutron Scattering Center (LANSCE).
The Accelerator Production of Tritium (APT) Target/Blanket and Materials Engineering Demonstration and Development (ED and D) Project has undertaken a major program of high-power materials irradiation at the Los Alamos Neutron Science Center (LANSCE) Accelerator. Five experiments have been installed in the Target A-6 area, immediately before the Isotope Production facility and the LANSCE bearnstop, where they will take a 1.0-mAmp-proton beam for up to 10 months. This operation is classed as a Nuclear Category (cat)-3 activity, since enough radionuclides buildup in the path of tie beam to exceed cat-3 threshold quantities. In the process of analyzing this buildup, it was realized that a loss of coolant accident (LOCA) could result in oxidation and subsequent vaporization of certain tungsten elements contained in our experiments. If this process occurs in the presence of steam, breakup of the water molecule would also provide a potentially explosive source of hydrogen, causing maximum release of radioactive aerosols to the surrounding environment. This process can occur in a matter of seconds. Such a release would result in potentially unacceptable dose to the public at the LANSCE site boundary, 800 meters from the A-6 area.
Waters, L.S.
Dynamics of quantum spin liquid and spin solid phases in IPA-CuCl3 under an applied magnetic field studied with neutron scattering
Inelastic and elastic neutron scattering is used to study spin correlations in the quasi-one-dimensional quantum antiferromagnet IPA-CuCl3 in strong applied magnetic fields. A condensation of magnons and commensurate transverse long-range ordering is observe at a critical field Hc=9.5 T. The field dependencies of the energies and polarizations of all magnon branches are investigated both below and above the transition point. Their dispersion is measured across the entire one-dimensional Brillouin zone in magnetic fields up to 14 T. The critical wave vector of magnon spectrum truncation Masuda et al., Phys. Rev. Lett. 96, 047210 2006 is found to shift from hc0,35 at HHC to hc=0.25 for HHC. A drastic reduction of magnon bandwidths in the ordered phase Garlea et al., Phys. Rev. Lett. 98, 167202 2007 is observed and studied in detail. New features of the spectrum, presumably related to this bandwidth collapse, are observed just above the transition field.
Zheludev, Andrey I [ORNL; Garlea, Vasile O [ORNL; Masuda, T. [Yokohama City University, Japan; Manaka, H. [Kagoshima University, Kagoshima JAPAN; Regnault, L.-P. [CEA, Grenoble, France; Ressouche, E. [CEA, Grenoble, France; Grenier, B. [CEA, Grenoble, France; Chung, J.-H. [National Institute of Standards and Technology (NIST); Qiu, Y. [National Institute of Standards and Technology (NIST); Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Kiefer, K. [Hahn-Meitner Institut, Berlin, Germany; Boehm, Martin [Institut Laue-Langevin (ILL)
reveals semiconducting phase and contributes to new understanding of iron-based superconductors Contact: Huibo Cao Neutron scattering measures samples too hot to hold Contact:...
BASIS Highlights | ORNL Neutron Sciences
in water and other glass-forming liquids, covering six research collaborations at ORNL Neutron scattering provides window into surface interactions High-performance...
techniques with neutron scattering at the General-Purpose SANS instrument at the ORNL High Flux Isotope Reactor. The cell mimics were vesicles (hollow spheres) made of...
Neutron Science and Supercomputing Come Together at Oak Ridge...
Neutron Science and Supercomputing Come Together at Oak Ridge National Lab (HPCWire) June 24, 2013 Next-generation neutron scattering requires next-generation data analysis...
Publications from Research Conducted at GP-SANS | ORNL Neutron Sciences
Publications from Research Conducted at GP-SANS Publications from Research Conducted at GP-SANS 2013 Publications Anovitz L. M., Cole D. R., Rother G., Allard L. F., Jackson A. J., Littrell K. C., "Diagenetic changes in macro- to nano-scale porosity in the St. Peter sandstone: an (ultra) small angle neutron scattering and backscattered electron imaging analysis", Geochimica et Cosmochimica Acta 102, 280-305 (2013). Black S. B., Chang Y., Bae C., Hickner M. A., "FTIR characterization of water-polymer interactions in superacid polymers", Journal of Physical Chemistry B 117, 16266-16274 (2013). Boukhalfa S., He L., Melnichenko Y. B., Yushin G., "Small-angle neutron scattering for in situ probing of ion adsorption inside micropores", Angewandte Chemie International Edition 52, 4618-4622 (2013).
Neutron Scattering Graduate Programs | ORNL Neutron Sciences
at ORNL and the higher education sector. A major focus has been on the development of cyber-enabled collaborative graduate courses with participation from multiple university and...
Neutron Scattering Portal | ORNL Neutron Sciences
services can be accessed through the User Portal. Helpful web links to other useful ORNL sites are also available via the portal. Getting Access to Resources Our computing...
Neutron Scattering User Program | Neutron Science | ORNL
through programs such as internships and postdoctoral programs. The instruments at HFIR and SNS can be used free of charge with the understanding that researchers will publish...
Phenomena of spin rotation and oscillation of particles (atoms, molecules) containing in a trap blowing on by wind of high energy particles in storage ring - new method of measuring of spin-dependent part of zero-angle coherent scattering amplitude
New experiment arrangement to study spin rotation and oscillation of particles of gas target through which beam of high energy particles passes is discussed. Such experiment arrangement make it realizable for storage ring and allows to study zero-angle scattering amplitude at highest possible energies. Life-time of particle beam in storage ring can reach several hours and even days. Life-time of particle in gas target (gas trap) is long too. Particles circulate in storage ring with frequency $\
Vladimir Baryshevsky
ORNL Neutron Sciences Users
SHUG banner SNS-HFIR User Group The SNS-HFIR User Group (SHUG) consists of all persons interested in using the neutron scattering facilities at Oak Ridge. It provides input to the...
HFIR Instrument Systems | ORNL Neutron Sciences
Click for more information about the HFIR beamline Experiment Hall Click for more information about the HFIR beamline Experiment Hall HFIR instrument layout. Click for details. Instruments at the High Flux Isotope Reactor The instrument suite at HFIR is supported by a variety of sample environments and on-site laboratories for user convenience. If you're unsure which instrument(s) would most benefit your research, or if you would like to request capabilities that you don't see here, please contact our user office. All HFIR Instrument fact sheets are also available in this single PDF document. Available to Users Beam Line Fact Sheet Instrument Name Contact CG-1 Development Beam Line Lee Robertson CG-1D PDF IMAGING - Neutron Imaging Prototype Facility Hassina Bilheux CG-2 PDF GP-SANS - General-Purpose Small-Angle Neutron Scattering Diffractometer Ken Littrell
Neutron Detection Efficiency of the
on improving the physical model used for neutron scattering in the resonance region. In many cases, the physical model for neutron scattering must take into account the motion of the target nuclei [2International Conference on Mathematics, Computational Methods & Reactor Physics (M&C 2009
Gilfoyle, Jerry
Neutron scattering and hydrogenous materials
... The next molecules, shown in brown, reside above the line defined by adjacent oxygen atoms, and in the sites above the benzene ring, shown in ...
NXS 2012 - Neutron Scattering School
ANL Facilities ANL Map (jpg) ANL Map (pdf) ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIRSNS Map Wireless Networks ORNL Safety & Security Rules ORNL...
NXS 2011 - Neutron Scattering School
NotesVideos Experiments ANL Facilities ANL Map ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIRSNS Map Wireless Networks ORNL Safety & Security Rules ORNL...
Neutron Scattering School (NXS2008)
Agenda updated 93008 Experiment Groups ORNL Experiments Experiments ORNL Facilities HFIR Facility SNS Facility HFIRSNS Map Access Requirements Wireless Network Access Rules &...
Neutron Scattering School (NXS2009)
Experiments Abstracts Discussion Schedule Experiments Experiment Groups ORNL Facilities HFIR Facility SNS Facility HFIRSNS Map Access Requirements Wireless Network Access Safety &...
EEE 562 Nuclear Reactor Theory and Design (3 hrs) Catalog Description: Principles of neutron chain reacting systems. Neutron diffusion and moderation.
important part of reactor physics. As the neutrons are produced in neutron induced fission of a fissile physical processes like neutron capture, elastic and inelastic scattering, upscattering, etc. Neutron technique is a scattering of free neutrons by matter. It is used in biophysics, physics, chemistry
New detector array improves neutron count capability at HFIR's Bio-SANS |
Bio-SANS neutron count capability improves Bio-SANS neutron count capability improves New detector array improves neutron count capability at HFIR's Bio-SANS Agatha Bardoel - June 29, 2012 Bio-SANS team that worked on installation of the new detector system. Front row, left to right: Doug Selby, Steve Hicks, Shuo Qian, Sai Venkatesh Pingali, Kathy Bailey, Amy Black Jones, and Derrick Williams. Back row, left to right: Ed Blackburn, John Palatinus, William Brad O'Dell, Mike Humphreys, Justin Beal, Ken Littrell, Greg Jones, Kevin Berry, Volker Urban, Randy Summers, and Ron Maples. Bio-SANS, the Biological Small-Angle Neutron Scattering Instrument at HFIR recently had a detector upgrade that will provide significantly improved performance that is more in line with the instrument's capability. Shorter experiment times are expected, which means more experiments can be
Supercool Neutrons (Ultracold Neutrons)
in the USA. Why neutrons? Neutrons possess physical properties that make them valuable investigative tools Spallation Neutron Source (SNS) The world's most intense pulsed accelerator-based neutron source. High Flux Isotope Reactor (HFIR) The highest flux reactor-based neutron source for condensed matter research
Martin, Jeff
Using Neutrons to Study Radioactive Materials
Symposium, Applied Neutron Scattering in Engineering and Materials Science Research ... to the unique infrastructure and specialized staff of the Nuclear Laboratory. Shielded cells enable neutron diffraction studies on highly radioactive�...
Filter-Analyzer Neutron Spectrometer (FANS)
... Soc., Div. Fuel Chem ... H. Kabbour, and CC Ahn, "Hydrogen Adsorption in MOF-74 Studied by Inelastic Neutron Scattering", in Life Cycle Analysis for ...
Neutron Data Analysis & Visualization | More Science | ORNL
the data sets generated by the increasingly powerful neutron scattering instruments at HFIR and SNS grow ever more massive, the facilities' users require significant advances in...
ORNL Neutron Sciences Instrument Fact Sheets
of each neutron scattering instrument at ORNL. You can also view SNS Instrument and HFIR Instrument pages that go to the related instrument's web pages. Detailed information...
Quantum Condensed Matter Division | Neutron Science | ORNL
instruments used for diffraction and inelastic neutron scattering at both SNS and HFIR. The science conducted by our staff members emphasizes materials with emergent...
Quantum Condensed Matter | Neutron Science | ORNL
Quantum Condensed Matter SHARE Quantum Condensed Matter Neutron scattering is a uniquely powerful probe for measuring the structure and dynamics of condensed matter. As such it is...
... J. Hwang, "Probing the Unusual Proton and Anion Mobility of LiBH ... Analysis of the Inelastic Neutron Scattering Spectra of Electron Donor-Acceptor ...
Experiment Facilities Experiment Facilities HFIR Experiment Facilities Neutron Scattering Facilities Target Positions Experiment Facilities in the Beryllium Reflector Large Removable Beryllium Facilities Small Removable Beryllium Facilities Control-Rod Access Plug Facilities Small Vertical Experiment Facilities Large Vertical Experiment Facilities Hydraulic Tube Facility Peripheral Target Positions Neutron Activation Analysis (NAA) Laboratory and Pneumatic Tube Facilities Slant Engineering Facilities Gamma Irradiation Facility Quality Assurance Requirements Contact Information Neutron Scattering Facilities The fully instrumented HFIR will eventually include 15 state-of-the-art neutron scattering instruments, seven of which will be designed exclusively for cold neutron experiments, located in a guide hall south of the reactor
Dr. Andrey Podlesnyak | ORNL Neutron Sciences
Andrey Podlesnyak Andrey Podlesnyak Dr. Andrey Podlesnyak Instrument Scientist: Cold Neutron Chopper Spectrometer (CNCS), SNS Education PhD in Physics, Institute for Metal Physics, Ekaterinburg, Russia Description of Research 2008 - present Instrument Scientist, Cold Neutron Chopper Spectrometer, Neutron Scattering Sciences Division, Oak Ridge National Laboratory 2006 - 2008 Instrument Scientist, single crystal diffractometer E-4, Hahn-Meitner-Institut, Berlin, Germany 2002 - 2006 Instrument Scientist, TOF spectrometer FOCUS, Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institute, Switzerland 2000 - 2002 Instrument Scientist, triple-axis spectrometer TASP, Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institute, Switzerland 1994 - 2000 Physicist, Institute for Metal Physics, Ekaterinburg, Russia
Industry - ORNL Neutron Sciences
Industry banner Industry banner Neutron scattering research has applications in practically every field, and neutron research at ORNL is leading to productive partnerships with the industrial and business communities. We welcome proposals for all types of research, including those involving proprietary work. Recent studies have led to discoveries with potential applications in fields such as medicine, energy, and various metals technologies. For more information, please see our recent research highlights. Research Collaborations Industry-Driven Research Benefits Plastics Manufacturing Corning uses VULCAN to test limits of ceramic material for car emission controls, filtration devices Neutrons Probe Inner Workings of Batteries Industry and Neutron Science: Working To Make a Match
NIST - Center for Neutron Research - Small-Angle Neutron ...
... To subscribe to the Google Calendar for the seminars see here. ... Instructions for subscribing to calendar. Online Services. Google Calendar. ...
Light and Color in Nature -Scattering Effects -
in reactor, nuclear bomb · Limit: Diffusion Theory Very many scattering events Effective anisotropy · Strongly wavelength-dependent (1/4) WS03/04: Light and Color in Nature Scattering Scattering Theory equation · Astrophysics Radiation density inside stars · Nuclear physics Neutron density & velocity
Assarsson, Ulf
SNS | Spallation Neutron Source | ORNL
SNS SNS Instruments Working with SNS Contact Us User Program Manager Laura Morris Edwards 865.574.2966 Spallation Neutron Source Home | User Facilities | SNS SNS | Spallation Neutron Source SHARE SNS is an accelerator-based neutron source in Oak Ridge, Tennessee, USA. This one-of-a-kind facility provides the most intense pulsed neutron beams in the world for scientific research and industrial development. The 80-acre SNS site is located on Chestnut Ridge and is part of Oak Ridge National Laboratory. Although most people don't know it, neutron scattering research has a lot to do with our everyday lives. For example, things like medicine, food, electronics, and cars and airplanes have all been improved by neutron scattering research. Neutron research also helps scientists improve materials used in a
Neutron sources and applications
Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.
Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)
ORNL neutron facilities deliver neutrons
The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) resumed full power operations on May 16, 2007. There were three experiment cycles of 23 to 25 days in FY2007 and another six are proposed for FY2008 beginning in November 2007. During FY 2007, the High Flux Isotope Reactor delivered 1178 operating hours to users. Commissioning of two SANS instruments is under way and these instruments will join the user program in 2008. The Neutron Scattering Science Advisory Committee endorsed language encouraging development of the science case for two instruments proposed for HFIR.
Ekkebus, Allen E [ORNL
Neutron Data Analysis and Visualization Division - ORNL Neutron...
develops software and hardware for the reduction and analysis of data taken on SNS and HFIR neutron scattering instruments. We work closely with the SNS and HFIR Data Acquisition...
Education banner Education banner Sunil Sinha A Chat with Sunil Sinha, Distinguished Professor of Physics at the University of California-San Diego and speaker at the recent CNMS-SNS Research Forum more... The purpose of the Spallation Neutron Source and the High Flux Isotope Reactor is to facilitate neutron scattering as an integral tool for scientific research and technological development across many scientific and engineering domains within the scientific, academic,and industrial communities. Coupled with this role is a recognized need to inspire, educate, and facilitate the next generation of users and hence foster enhanced use of the unique neutron scattering facilities at ORNL. This is the central theme of the education activities within the Neutron Sciences Directorate (NScD).
About US | ORNL Neutron Sciences
banner What's the Big Deal About Neutron Scattering? Who Conducts Research at SNS and HFIR? Why Do They Come Here? Where Are We? Oak Ridge National Laboratory is home to two of...
Observation of Neutrons with a Gadolinium Doped Water Cerenkov Detector
Spontaneous and induced fission in Special Nuclear Material (SNM) such as 235U and 239Pu results in the emission of neutrons and high energy gamma-rays. The multiplicities of and time correlations between these particles are both powerful indicators of the presence of fissile material. Detectors sensitive to these signatures are consequently useful for nuclear material monitoring, search, and characterization. In this article, we demonstrate sensitivity to both high energy gamma-rays and neutrons with a water Cerenkov based detector. Electrons in the detector medium, scattered by gamma-ray interactions, are detected by their Cerenkov light emission. Sensitivity to neutrons is enhanced by the addition of a gadolinium compound to the water in low concentrations. Cerenkov light is similarly produced by an 8 MeV gamma-ray cascade following neutron capture on the gadolinium. The large solid angle coverage and high intrinsic efficiency of this detection approach can provide robust and low cost neutron and gamma-ray detection with a single device.
S. Dazeley; A. Bernstein; N. S. Bowden; R. Svoboda
Biology and Soft Matter Division | Neutron Science | ORNL
Biology and Soft Matter Division Biology and Soft Matter Division SHARE Biology and Soft Matter Division BSMD Director Paul Langan The Biology and Soft Matter Division (BSMD) operates an external user program for biological and soft matter research using neutron techniques at SNS and HFIR. Division personnel enable the research initiated by external users by acting as instrument responsible scientists and local contacts on a range of different beam lines. BSMD works closely with the Center for Structural Molecular Biology. Diffraction, small-angle scattering, and reflectometry are ideal methods for studying structure and organization from the atomic to the micron length scales, and neutron spectroscopic methods characterize self and collective motions from picosecond to microsecond timescales. These
RIJKSUNIVERSITEIT GRONINGEN In-situ element analysis from gamma-ray and neutron spectra using a
experimentally. Figure 2.1: Schematic presentation of the neutron elastic scattering process (CANDU04). #12 process (CANDU04). Instead of re-emitting a neutron as in inelastic scattering, the compound nucleus may
Groningen, Rijksuniversiteit
Hydrogen absorption in epitaxial W/Nb(001) and polycrystalline Fe/Nb(110) multilayers studied in-situ by X-ray/neutron scattering techniques and X-ray absorption spectroscopy
Hydrogen can be absorbed in large quantities by 100 {angstrom} thin Nb layers embedded in epitaxial W/Nb and polycrystalline Fe/Nb multilayers. The solubility and the hydrogen-induced structural changes of the host lattice are explored in-situ by small-angle neutron/X-ray reflectometry and high-angle diffraction. These measurements reveal for both systems that the relative out-of-plane expansion of the Nb layers is considerably larger than the relative increase of the Nb interplanar spacing indicating two distinctly different mechanisms of hydrogen absorption. In Fe/Nb multilayers, hydrogen expands the Nb interplanar spacing in a continuous way as function of the external pressure. In contrast, the Nb lattice expansion is discontinuous in epitaxial W/Nb multilayers: A jump in the Nb(002) Bragg reflection position occurs at a critical hydrogen pressure of 1 mbar. In-situ EXAFS spectroscopy also exhibits an irreversible expansion of the Nb lattice in the film plane for p{sub H{sub 2}}> 1 mbar. This can be regarded as a structural phase transition from an exclusively out-of-plane to a three-dimensionally expanded state at low and high hydrogen pressures, respectively.
Klose, F.; Rehm, C.; Fieber-Erdmann, M.; Holub-Krappe, E.; Bleif, H. J.; Sowers, H.; Goyette, R.; Troger, L.; Maletta, H.
Neutron Diffraction @ TOPAZ
Topaz Guide Bender Topaz Guide Bender Neutron Diffraction @ TOPAZ Workshop on Single Crystal Neutron Diffraction picture 2 September 29 - October 1, 2011 * Spallation Neutron Source * Oak Ridge National Laboratory * Oak Ridge TN, USA TOPAZ 2011 Home Contacts Agenda and Important Deadlines Registration and Payment filler Workshop summary and purpose A workshop on single crystal neutron diffraction will be held at the Spallation Neutron Source at the Oak Ridge National Laboratory (ORNL). It will present invited and contributed talks to showcase cutting edge science and examples where neutron diffraction can make significant contributions; and provide training in neutron structure analysis and sample screening for the preparation of instrument beam-time proposals. TOPAZ is a high resolution wavelength-resolved Laue diffractometer with a versatile sample environment. Commissioning user experiments have demonstrated successfully the instrument capability for structural study of a vitamin B12 derivative, ion distribution in Li-ion battery materials, order and disorder in shape memory intermetallics, magnetic phase transition in multiferroic single crystal and functional thin films. The workshop is directed towards experienced neutron diffraction users and new users alike and encourages members to highlight their research and interest in structure analysis and investigation. The workshop will give opportunity to bring your own single crystal and screen sample quality and scattering power on TOPAZ @ room temperature, to evaluate data collection time and quality for an anticipated experiment. Finally, an opportunity to compose a proposal for neutron beam time (http://neutrons.ornl.gov/users/proposals.shtml) with staff will be provided in the framework of the workshop. The workshop format is well suited for researchers to contribute by showcasing their research and bring their research group or graduate student, who would like to test a single crystal sample. User access training for the ORNL neutron scattering facility will be included. It will be valid for future experiments.
Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.
Former User Group Chair Enthusiastic About Relevance of Neutron Scattering Former User Group Chair Enthusiastic About Relevance of Neutron Scattering to Industrial Research Former User Group Chair Mike Crawford Mike Crawford, DuPont Research and Development. The drive is intensifying to encourage research partnerships between Neutron Sciences and private industry. Such partnerships, a long-term strategic goal set by the DOE's Basic Energy Sciences Advisory Committee, will deliver industry and its technological problems to SNS and HFIR, where joint laboratory-industry teams can use the unparalleled resources available here to resolve them. "SNS is a tremendous facility. It has the potential to have a couple of thousand user visits a year and, if they build another target station in the future, you're probably talking about 4000 user visits a year,"
Light scattering for aerogel characterization
for aerogel characterization for aerogel characterization Title Light scattering for aerogel characterization Publication Type Journal Article Year of Publication 1998 Authors Hunt, Arlon J. Journal Journal of Non-Crystalline Solids Volume 225 Pagination 303-306 Keywords aerogel, light scattering, microstructure Abstract Light scattering is a useful tool to evaluate aerogel clarity, study its structure, pore size, mechanical strain, and examine the modes of sol-gel evolution that determine its microstructure. Ultraviolet-visible transmission spectroscopy can be used to study the wavelength dependent scattering to readily compare aerogels of differing origins, thickness, and to evaluate effects of residual contaminants. Infrared reflectance measurements can be used to determine the effective real and imaginary indices of refraction of porous aerogel materials for material property and radiant heat transfer studies. Measurements of scattering at a fixed angle can be used for quality control, to evaluate sources of scattering, and study inhomogeneities. Measurement of the Mueller matrix (describing the 16-element angle-dependent transformation of intensity and polarization of incident to scattered light) provides information about the anisotropy, large pore fraction, induced stresses, microstructure and inhomogeneities in the aerogel. The time evolution of scattering before and after gel formation gives information.
Design and estimated performance of a new neutron guide system for the NCNR expansion project
An integral part of the National Institute of Standards and Technology Center for Neutron Research (NCNR) expansion project is the addition of five cold neutron guide tubes serving multiple experimental stations in an expanded guide hall. The guides have curved-straight arrangements in the horizontal plane, employing horizontally or vertically defocusing and focusing sections in some cases to improve transmission efficiency or for beam reshaping. The horizontally curved sections eliminate direct lines of sight between the source and the experimental stations, and the outer (concave) surfaces generally have higher critical angles than the inner (convex) surfaces. These features result in well-filtered cold neutron beams with no intensity losses at shorter wavelengths with respect to curved guides having the higher critical angle coatings on both surfaces. For all guides the critical angle of the outer coating of the curved section is selected to achieve a desirable characteristic wavelength, consistent with the instrument requirements. On guides where the scattering-plane beam divergence must be strictly limited, the inner radial coatings of the curved sections and the side coatings and lengths of the final straight sections are chosen to produce the desired beam divergence while the outer radial coating is selected so as to obtain a spatial-angular uniformity of the transmitted beam that is not achievable using a curved guide alone. The long-wavelength transmission of such guides tends to exceed that of equivalent straight guides using crystal filters.
Cook, J. C. [NIST Center for Neutron Research, 100 Bureau Drive, Stop 6103, Gaithersburg, Maryland 20899-6103 (United States)
Glossary Term - Neutron Emission
Neutron Previous Term (Neutron) Glossary Main Index Next Term (Niobe) Niobe Neutron Emission After neutron emission, an atom contains one less neutron. Neutron emission is one...
ORNL Neutron Sciences Instruments
Instruments banner Instruments banner ORNL Neutron Sciences Instruments SNS and HFIR provide researchers with two complementary world-class suites of neutron scattering instruments and beam lines. All the instruments are supported by a variety of sample environments and data analysis and visualization capabilities. Before submitting a proposal for a specific instrument, please contact the appropriate instrument scientist to make sure your research is feasible for that instrument. Instruments Currently Available to Users SNS Beam Line Instrument Name HFIR Beam Line Instrument Name 1B NOMAD Nanoscale-Ordered Materials Diffractometer CG-1 Development Beam Line 2 BASIS Backscattering Spectrometer CG-1D IMAGING Neutron Imaging Prototype Facility 3 SNAP Spallation Neutrons and Pressure Diffractometer CG-2 GP-SANS
Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering
Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.
Proffen, Thomas E [Los Alamos National Laboratory; Kim, Yiung- Il [UCSB; Cadars, Sylvian [UCSB; Shayib, Ramzy [UCSB; Feigerle, Charles S [UNIV OF TENNESSEE; Chmelka, Bradley F [UCSB; Seshadri, Ram [UCSB
DIFFERENTIAL NEUTRON THERMALIZATION. Annual Summary Report, October 1, 1961 through September 30, 1962
Experimental and theoretical work on the interaction mechanisms by which neutrons exchange energy with H atoms involves treating neutron thermalization as neutron interactions with energy levels in the atoms. Cold moderators are presently being studied in order to optimize the source of cold neutrons. Cold neutrons are provided from an accelerator arrangement that directs electrons against a Fansteel target producing fast neutrons. Thermal neutrons, produced by moderation of fast neutrons, are passed through a chopper. Several moderators are evaluated, and neutron emission time measurements by crystal diffraction and beam chopper techniques point out emission time dependence on thickness, moderator, and temperature. The neutron beam chopper used presently is described, and results of neutron scattering by liquid para- and orthohydrogen are displayed and compared with theoretical predictions made with a perfect hydrogen gas model. Inelastic scattering of neutrons by liquid H is discussed, and theoretical and experimental results of inelastic scattering by polyethylene are also included. (D.C.W.)
Whittemore, W L
The plane of polarization of a beam of polarized neutrons is changed by this invention, and the plane can be flipped back and forth quicitly in two directions in a trouble-free manner. The invention comprises a guide having a plurality of oppositely directed magnets forming a gap for the neutron beam and the gaps are spaced longitudinally in a spiral along the beam at small stepped angles. When it is desired to flip the plane of polarization the magnets are suitably rotated to change the direction of the spiral of the gaps. (AEC)
Sailor, V.L.; Aichroth, R.W.
Neutron Radiography
Table 8 Characteristics of neutron radiography at various neutron-energy ranges...Good discrimination between materials and ready availability
Neutron Sources
Table 1 Characteristics of neutron radiography at various neutron-energy ranges...Good discrimination between materials, and ready
Awards 2007 | ORNL Neutron Sciences
7 7 Staff Awards: 2007 Chakoumakos elected MSA Fellow Bryan Chakoumakos Neutron scientist Bryan Chakoumakos was recently elected a fellow of the Mineralogical Society of America. A member of the Neutron Scattering Science Division, Bryan leads the Single-Crystal Diffraction Group. The group has five neutron scattering instruments in various stages of design and construction, located at HFIR and SNS. The MSA was founded in 1919 and, among other goals, encourages fundamental research on natural materials and supports education through its publications, educational grants, and courses. Pharos Neutron Detector System Researchers at the Department of Energy's Oak Ridge National Laboratory have won six R&D 100 Awards, given annually by R&D Magazine to the year's
Videos & Tutorials - Science | ORNL Neutron Sciences
and 2010 National School on Neutron & X-Ray Scattering. This annual school is hosted by ORNL and Argonne National Laboratory. Some of this material is protected by copyright....
Data Analysis & Visualization Division | Neutron Science | ORNL
Low energy neutron-proton interactions
There have been few measurements of cross sections for neutron-proton scattering and radiative capture below 1 MeV. Those measurements which do exist are at a small number of energies and are often inconsistent with ...
Daub, Brian (Brian Hollenberg)
Coated gallium arsenide neutron detectors : results of characterizationmeasurements.
Effective detection of special nuclear materials (SNM) is essential for reducing the threat associated with stolen or improvised nuclear devices. Passive radiation detection technologies are primarily based on gamma-ray detection and subsequent isotope identification or neutron detection (specific to neutron sources and SNM). One major effort supported by the Department of Homeland Security in the area of advanced passive detection is handheld or portable neutron detectors for search and localization tasks in emergency response and interdiction settings. A successful SNM search detector will not only be able to confirm the presence of fissionable materials but also establish the location of the source in as short of time as possible while trying to minimize false alarms due to varying background or naturally occurring radioactive materials (NORM). For instruments based on neutron detectors, this translates to detecting neutrons from spontaneous fission or alpha-n reactions and being able to determine the direction of the source (or localizing the source through subsequent measurements). Polyethylene-coated gallium arsenide detectors were studied because the detection scheme is based on measuring the signal in the gallium arsenide wafers from the electrical charge of the recoil protons produced from the scattering of neutrons from the hydrogen nucleus. The inherent reaction has a directional dependence because the neutron and hydrogen nucleus have equivalent masses. The assessment and measurement of polyethylene-coated gallium arsenide detector properties and characteristics was the first phase of a project being performed for the Department of Homeland Security and the results of these tests are reported in this report. The ultimate goal of the project was to develop a man-portable neutron detection system that has the ability to determine the direction of the source from the detector. The efficiency of GaAs detectors for different sizes of polyethylene layers and different angles between the detector and the neutron source were determined. Preliminary measurements with a neutron generator based on a deuterium-tritium reaction ({approx}14 MeV neutrons) were performed and the results are discussed. This report presents the results of these measurements in terms of efficiency and angular efficiency and compares them to Monte Carlo calculations to validate the calculation scheme in view of further applications. Based on the results of this study, the polyethylene-coated gallium arsenide detectors provide adequate angular resolution based on proton recoil detection from the neutron scattering reaction from hydrogen. However, the intrinsic efficiency for an individual detector is extremely low. Because of this low efficiency, large surface area detectors ( or a large total surface area from many small detectors) would be required to generate adequate statistics to perform directional detection in near-real time. Large surface areas could be created by stacking the detector wafers with only a negligible attenuation of source neutrons. However, the cost of creating such a large array of GaAs is cost-prohibitive at this time.
Klann, R. T.; Perret, G.; Sanders, J.
Portable Neutron Sensors for Emergency Response Operations
This article presents the experimental work performed in the area of neutron detector development at the Remote Sensing Laboratory�Andrews Operations (RSL-AO) sponsored by the U.S. Department of Energy, National Nuclear Security Administration (NNSA) in the last four years. During the 1950s neutron detectors were developed mostly to characterize nuclear reactors where the neutron flux is high. Due to the indirect nature of neutron detection via interaction with other particles, neutron counting and neutron energy measurements have never been as precise as gamma-ray counting measurements and gamma-ray spectroscopy. This indirect nature is intrinsic to all neutron measurement endeavors (except perhaps for neutron spin-related experiments, viz. neutron spin-echo measurements where one obtains ?eV energy resolution). In emergency response situations generally the count rates are low, and neutrons may be scattered around in inhomogeneous intervening materials. It is also true that neutron sensors are most efficient for the lowest energy neutrons, so it is not as easy to detect and count energetic neutrons. Most of the emergency response neutron detectors are offshoots of nuclear device diagnostics tools and special nuclear materials characterization equipment, because that is what is available commercially. These instruments mostly are laboratory equipment, and not field-deployable gear suited for mobile teams. Our goal is to design and prototype field-deployable, ruggedized, lightweight, efficient neutron detectors.
Breast Tissue Imaging | ORNL Neutron Sciences
Neutron scattering measures samples too hot to hold Neutron scattering measures samples too hot to hold Research Contact: Kenneth Kelton August 2013 Liquids and glasses can have unique optical, electronic, and structural applications but are poorly understood compared to crystalline materials, limiting the ability to take advantage of the characteristics of glasses in a range of applications. Containers can react with molten samples at high temperatures or can favor the growth of crystals over the formation of glasses. Using the chemical and isotopic sensitivity of neutron scattering to understand these disordered structures requires a new capability to hold samples in a neutron beam at high temperature without using a solid physical container. New sample environment equipment at Oak Ridge National Laboratory's (ORNL) Spallation Neutron Source (SNS) enables scientists to
The search for Nanobubbles by using specular and off-specular Neutron Reflectivity
In this work we show an example where specular and off-specular neutron reflectivity can give insight into the structure of solid/liquid interfaces. The presence of nanobubbles and/or a depletion layer at the interface has been long discussed and generated a plethora of controversial scientific results. By means of time of flight neutron reflectometry (NR) and grazing incidence small angle scattering (GISANS), we studied the interface between hydrophobized silicon and heavy water in normal and nigrogen gas enriched state. Our results from the specular reflectivities can be explained without an assumption of a depletion layer and the off-specular measurements show no change with nitrogen super saturated water, which is consistent with the assumption that no nanobubbles are present. We discuss the experiments, in terms of the maximum surface coverage of nanobubbles that could be present on the hydrophobic surface compatible with the limit of sensitivity of NR and GISANS.
Philipp Gutfreund; Marco Maccarini; Andrew Dennison; Max Wolff
Design and operation of the wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source
The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of {sup 3}He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and sample environment equipment. ARCS views the SNS decoupled ambient temperature water moderator, using neutrons with incident energy typically in the range from 15 to 1500 meV. This range, coupled with the large detector coverage, allows a wide variety of studies of excitations in condensed matter, such as lattice dynamics and magnetism, in both powder and single-crystal samples. Comparisons of early results to both analytical and Monte Carlo simulation of the instrument performance demonstrate that the instrument is operating as expected and its neutronic performance is understood. ARCS is currently in the SNS user program and continues to improve its scientific productivity by incorporating new instrumentation to increase the range of science covered and improve its effectiveness in data collection.
Abernathy, D. L.; Stone, M. B.; Loguillo, M. J.; Lucas, M. S.; Delaire, O. [Neutron Scattering Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831 (United States); Tang, X.; Lin, J. Y. Y.; Fultz, B. [California Institute of Technology, W. M. Keck Laboratory 138-78, Pasadena, California 91125 (United States)
The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically-focused neutron guide, high speed magnetic bearing choppers and a massive array of 3He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and sample environment equipment. ARCS views the SNS decoupled ambient temperature water moderator, using neutrons with incident energy typically in the range from 15 to 1500 meV. This range, coupled with the large detector coverage, allows a wide variety of studies of excitations in condensed matter, such as lattice dynamics and magnetism, in both powder and single-crystal samples. Comparisons of early results to both analytical and Monte Carlo simulation of the instrument performance demonstrate that the instrument is operating as expected and its neutronic performance is understood. ARCS is currently in the SNS user program, and continues to improve its scientific productivity by incorporating new instrumentation to increase the range of science covered and improve its effectiveness in data collection.
Abernathy, Douglas L [ORNL; Stone, Matthew B [ORNL; Loguillo, Mark [ORNL; Lucas, Matthew [Air Force Research Laboratory, Wright-Patterson AFB, OH; Delaire, Olivier A [ORNL; Tang, Xiaoli [California Institute of Technology, Pasadena; Lin, J. Y. Y. [California Institute of Technology, Pasadena; Fultz, B. [California Institute of Technology, Pasadena
ABAREX: A neutron spherical optical-statistical model code
The spherical optical-statistical model is briefly reviewed and the capabilities of the neutron scattering code, ABAREX, are presented. Input files for ten examples, in which neutrons are scattered by various nuclei, are given and the output of each run is discussed in detail.
Lawson, R.D.
Publications from Research Conducted at EQ-SANS | ORNL Neutron Sciences
Publications from Research Conducted at EQ-SANS Publications from Research Conducted at EQ-SANS 2013 Publications Banuelos J. L., Feng G., Fulvio P. F., Li S., Rother G., Dai S., Cummings P. T., Wesolowski D. J., "Densification of ionic liquid molecules within a hierarchical nanoporous carbon structure revealed by small angle scattering and molecular dynamics simulation", Chemistry of Materials , (2013). Choi I., Malak S. T., Xu W., Heller W. T., Tsitsilianis C., Tsukruk V. V., "Multicompartmental microcapsules from star copolymer micelles", Macromolecules 46, 1425-1436 (2013). Do C., Chen W.-R., Hong K., Smith G. S., "Equilibrium structure of a triblock copolymer system revealed by mesoscale simulation and neutron scattering", Physica B: Condensed Matter 430, 87-94 (2013).
Glossary Term - Neutron
Neutrino Previous Term (Neutrino) Glossary Main Index Next Term (Neutron Emission) Neutron Emission Neutron A Neutron Neutrons are uncharged particles found within atomic nuclei....
About Neutrons
Neutron Basics Neutron Basics A neutron is one of the fundamental particles that make up matter. This uncharged particle exists in the nucleus of a typical atom, along with its positively charged counterpart, the proton. Protons and neutrons each have about the same mass, and both can exist as free particles away from the nucleus. In the universe, neutrons are abundant, making up more than half of all visible matter. Find Out What a Neutron Is Youtube icon Properties of Neutrons How Can Neutrons Be Used for Research? Image of glucose movement in plants Neutron imaging techniques have been able to determine the precise movement of glucose in plants. This knowledge can help scientists better understand how biomass can be efficiently converted into fuel. Neutrons have many properties that make them ideal for certain types of
Time resolved side scatter diagnostics at NOVA
Side scattering of the radiation during the interaction of a laser beam with the long scale length plasma in hohlraum is a difficult problem of relevance to the viability of ICF. It is important to measure the absolute amount of the laser side scatter as well as the angular distribution of that scatter. The OSA diagnostics has been implemented on NOVA to measure these quantities. We have implemented a fiber-optically coupled streak camera to measure the temporally and angularly resolved side scatter radiation at 351 nm at 9 different angles. Filtered PIN diodes were positioned at 31 various angles in the E-field planed and B-field plane of the incident probe beam to sample and measure the scattered radiation at the 351 nm wavelength of the probe. The diode data was used to calibrate the Brillouin power received by the 9 strategically located fiber optic channels. This presentation will describe the OSA and associated diagnostics.
Kyrala, G.A.; Evans, S.C.; Jimerson, J.R.; Fernandez, J.C.
Neutron beam imaging at neutron spectrometers at Dhruva
A low efficiency, 2-Dimensional Position Sensitive Neutron Detector based on delay line position encoding is developed. It is designed to handle beam flux of 10{sup 6}-10{sup 7} n/cm{sup 2}/s and for monitoring intensity profiles of neutron beams. The present detector can be mounted in transmission mode, as the hardware allows maximum neutron transmission in sensitive region. Position resolution of 1.2 mm in X and Y directions, is obtained. Online monitoring of beam images and intensity profile of various neutron scattering spectrometers at Dhruva are presented. It shows better dynamic range of intensity over commercial neutron camera and is also time effective over the traditionally used photographic method.
Desai, Shraddha S.; Rao, Mala N. [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)
Tentative Organization of the NCNR Small Angle Scattering ...
... 6:00 Recess � return to hotel 7:00 Bus leaves hotel for Summer School Banquet 9:30 Bus leaves restaurant to return to hotel Page 5. ...
Research Highlights | Neutron Science | ORNL
Research Highlights Research Highlights Biology & Medicine Biotechnology & Energy Fundamental Physics Imaging Magnetism Materials Nanotechnology Superconductivity Facilities and Capabilities Instruments User Program Publications and Resources Science and Education News and Awards NScD Careers Supporting Organizations Neutron Science Home | Science & Discovery | Neutron Science | Research Highlights SHARE Research Highlights No current Research Highlights found. 1-10 of 43 Results Comprehensive phonon "map" offers direction for engineering new thermoelectric devices January 08, 2014 - To understand how to design better thermoelectric materials, researchers are using neutron scattering at SNS and HFIR to study how a compound known as AgSbTe2, or silver antimony telluride, is
Angle performance on optima MDxt
Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16 Degree-Sign (1{sigma}). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1 Degree-Sign (1{sigma}).
David, Jonathan; Kamenitsa, Dennis [Axcelis Technologies, Inc., 108 Cherry Hill Dr, Beverly, MA 01915 (United States)
Recent Neutron Scattering Results from Geometrically ...
... of Physics, The University of Texas at Austin, Austin, Texas 78712. ... Recently, the quantized energy states under magnetic fields (Landau levels) and ...
Chapter 199 NEUTRON SCATTERING STUDIES OF ...
... 4) materials. The basic crystal structure is tetragonal I4/mmm (T phase) in which the Cu Page 5. LANTHANIDE MAGNETIC ...
... Fast pyrolysis is one process that can be used to convert woody biomass into fuels and chemicals, however the liquid product created is an ...
Forum on Inelastic Neutron Scattering (FINS 2011)
sessions are planned for discussions of inelastic instrumentation needs for the SNS and HFIR, sample environment equipment for the inelastic suite, enabling programmatic research...
Neutron Scattering Investigation of the Structure and ...
... floor, their detrimental formation in gas and oil pipelines, possible existence ... Last modified 07-March-2005 by website owner: NCNR (attn: Yun Liu).
New States of Matter and their Excitations Joint Meeting 12 - 14 September, 2012 Clinch River Cabin * Oak Ridge, Tennessee, USA About the School Agenda Organizers Venue filler...
Ultracold Neutron Production in a Pulsed Neutron Beam Line
We present the results of an Ultracold neutron (UCN) production experiment in a pulsed neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal expected can be overwhelmed by the large background associated with the scattering of the primary cold neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-D$_2$ is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O$_2$. In addition to setting the overall detection efficiency in the...
Lavelle, C M; Manus, G; McChesney, P M; Salvat, D J; Shin, Y; Makela, M; Morris, C; Saunders, A; Couture, A; Young, A R; Liu, C -Y
We present the results of an Ultracold neutron (UCN) production experiment in a pulsed neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal expected can be overwhelmed by the large background associated with the scattering of the primary cold neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-D$_2$ is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O$_2$. In addition to setting the overall detection efficiency in the apparatus, UCN production data using solid D$_2$ suggest that the UCN upscattering cross-section is smaller than previous estimates, indicating the deficiency of the incoherent approximation widely used to estimate inelastic cross-sections in the thermal and cold regimes.
C. M. Lavelle; W. Fox; G. Manus; P. M. McChesney; D. J. Salvat; Y. Shin; M. Makela; C. Morris; A. Saunders; A. Couture; A. R. Young; C. -Y. Liu
Structure and Dynamics of Cholesterol-Containing Polyunsaturated Lipid Membranes Studied by Neutron Diffraction and NMR
by Neutron Diffraction and NMR Mihaela Mihailescu � Olivierwas carried out by neutron diffraction, 2 H-NMR and 13C-MAS NMR. Scattering length distribution func- tions of
Mihailescu, Mihaela; Soubias, Olivier; Worcester, David; White, Stephen H.; Gawrisch, Klaus
Neutron dosimetry
A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.
Quinby, Thomas C. (Kingston, TN)
Polarized Neutron in Structural Biology Present and Future Outlook
Hydrogen has a strong polarization-dependent neutron scattering cross section. This property has been exploited in the study of soft matters, especially biological macromolecules. When a polarized neutron beam is scattered off a polarized hydrogenous sample, the otherwise large hydrogen incoherent cross section is drastically reduced while the coherent signal is significantly increased. Past experiments have demonstrated the potentials and benefits of polarized neutron scattering from soft materials. The main technical challenge of polarized neutron scattering from biological matters lies at sample polarization. Dynamic nuclear polarization is a proven yet rather sophisticated technique. Its complexity is one of the main reasons for the technique's slow adoption. The future of polarized neutron scattering in biology may rest largely in neutron protein crystallography. Polarization of protein crystals is much easier to accomplish, since protein crystals are typically rather small (<<1 mm) and only require small and easy- to-operate polarization apparatuses. In addition, the high resolution nature of neutron protein crystallography means that we will be able to study individual atoms using the polarized neutron scattering technique.
Zhao, Jinkui [ORNL; Robertson, Lee [ORNL; Herwig, Kenneth W [ORNL; Crabb, Don [University of Virginia
Internal Wave Reflection and Scatter from Sloping Rough Topography
Internal gravity waves propagating in a uniformly stratified ocean are scattered on reflection from a rough inclined boundary. The boundary is inclined at angle ? to the horizontal and the roughness is represented by superimposed sinusoidal ...
S. A. Thorpe
Microstructural Mapping Using High-Energy X-Ray Scattering
Abstract Scope, Advanced characterization methods at the APS permit unique in- situ ... The combination of an undulator source, brilliance preserving optics and focusing .... Ultra-Small-Angle X-Ray Scattering�X-Ray Photon Correlation�...
Weak Interaction Neutron Production Rates in Fully Ionized Plasmas
Employing the weak interaction reaction wherein a heavy electron is captured by a proton to produce a neutron and a neutrino, the neutron production rate for neutral hydrogen gases and for fully ionized plasmas is computed. Using the Coulomb atomic bound state wave functions of a neutral hydrogen gas, our production rate results are in agreement with recent estimates by Maiani {\\it et al}. Using Coulomb scattering state wave functions for the fully ionized plasma, we find a substantially enhanced neutron production rate. The scattering wave function should replace the bound state wave function for estimates of the enhanced neutron production rate on water plasma drenched cathodes of chemical cells.
A. Widom; J. Swain; Y. N. Srivastava
Long-Range Neutron Detection
A neutron detector designed for detecting neutron sources at distances of 50 to 100 m has been constructed and tested. This detector has a large surface area (1 m{sup 2}) to enhance detection efficiency, and it contains a collimator and shielding to achieve direction sensitivity and reduce background. An unusual feature of the detector is that it contains no added moderator, such as polyethylene, to moderate fast neutrons before they reach the {sup 3}He detector. As a result, the detector is sensitive mainly to thermal neutrons. The moderator-free design reduces the weight of the detector, making it more portable, and it also aids in achieving directional sensitivity and background reduction. Test results show that moderated fission-neutron sources of strength about 3 x 10{sup 5} n/s can be detected at a distance out to 70 m in a counting time of 1000 s. The best angular resolution of the detector is obtained at distances of 30 m or less. As the separation .distance between the source and detector increases, the contribution of scattered neutrons to the measured signal increases with a resultant decrease in the ability to detect the direction to a distant source. Applications for which the long-range detector appears to be suitable include detecting remote neutron sources (including sources in moving vehicles) and monitoring neutron storage vaults for the intrusion of humans and the effects they make on the detected neutron signal. Also, the detector can be used to measure waste for the presence of transuranic material in the presence of high gamma-ray background. A test with a neutron source (3 x 10{sup 5} n/s) in a vehicle showed that the detector could readily measure an increase in count rate at a distance of 10 m for vehicle speeds up to 35 mph (the highest speed tested). These results. indicate that the source should be detectable at this distance at speeds up to 55 mph.
AJ Peurrung; DC Stromswold; RR Hansen; PL Reeder; DS Barnett
Interactions between Ether Phospholipids and Cholesterol as Determined by Scattering and Molecular Dynamics Simulations
Cholesterol and ether lipids are ubiquitous in mammalian cell membranes, and their interactions are crucial in ether lipid mediated cholesterol trafficking. We report on cholesterol s molecular interactions with ether lipids as determined using a combination of small-angle neutron and Xray scattering, and all-atom molecular dynamics (MD) simulations. A scattering density profile model for an ether lipid bilayer was developed using MD simulations, which was then used to simultaneously fit the different experimental scattering data. From analysis of the data the various bilayer structural parameters were obtained. Surface area constrained MD simulations were also performed to reproduce the experimental data. This iterative analysis approach resulted in good agreement between the experimental and simulated form factors. The molecular interactions taking place between cholesterol and ether lipids were then determined from the validated MD simulations. We found that in ether membranes cholesterol primarily hydrogen bonds with the lipid headgroup phosphate oxygen, while in their ester membrane counterparts cholesterol hydrogen bonds with the backbone ester carbonyls. This different mode of interaction between ether lipids and cholesterol induces cholesterol to reside closer to the bilayer surface, dehydrating the headgroup s phosphate moiety. Moreover, the three-dimensional lipid chain spatial density distribution around cholesterol indicates anisotropic chain packing, causing cholesterol to tilt. These insights lend a better understanding of ether lipid-mediated cholesterol trafficking and the roles that the different lipid species have in determining the structural and dynamical properties of membrane associated biomolecules.
Pan, Jianjun [ORNL; Cheng, Xiaolin [ORNL; Heberle, Frederick A [ORNL; Mostofian, Barmak [ORNL; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Drazba, Paul [ORNL; Katsaras, John [ORNL
Protein Activity that Protects Our DNA - Research Highlights | ORNL Neutron
Neutrons help shed light on critical protein activity that protects our DNA Neutrons help shed light on critical protein activity that protects our DNA "New study provides a framework for understanding how protein works and how it stimulates the DNA processing machines" Research Contact: Walter Chazin Illustration of the change in architecture of the essential eukaryotic ssDNA binding protein RPA as it engages progressively longer segments of ssDNA. Small-angle x-ray scattering data are displayed in the background for the DNA binding core of RPA in its DNA-free state (green) and when engaged on 10 (yellow), 20 (red, and 30 (blue) nucleotide ssDNA substrates. Overlaid molecular surfaces and ribbon representations of the three distinct architectural states of RPA are shown, one for the DNA-free protein and the two others for the initial and fully ssDNA-engaged modes, revealing the progressive compaction of the protein as it binds to the substrate. The RPA70 subunit is colored in blue, RPA32 in green, and RPA14 in red, with ssDNA displayed as a yellow ribbon.
... for Neutron Reaction Rate Measurements, JA Grundl, V. Spiegel, CM Eisenhauer, HT Heaton II, DM Gilliam (NBS), and J. Bigelow (ORNL), Nucl. ...
A system for fast neutron radiography
A system has been designed and a neutron generator installed to perform fast neutron radiography. With this sytem, objects as small as a coin or as large as a waste drum can be radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3x10{sup 10} neutrons/second with an average energy of 14.5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available cassettes. The cassettes have been modified to include a thin sheet of plastic to convert neutrons to protons through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9x10{sup 7} to 3.8x10{sup 8} n/cm{sup 2} depending on the type of screen and film.
Klann, R.T.
Spinning angle optical calibration apparatus
An optical calibration apparatus is provided for calibrating and reproducing spinning angles in cross-polarization, nuclear magnetic resonance spectroscopy. An illuminated magnifying apparatus enables optical setting an accurate reproducing of spinning "magic angles" in cross-polarization, nuclear magnetic resonance spectroscopy experiments. A reference mark scribed on an edge of a spinning angle test sample holder is illuminated by a light source and viewed through a magnifying scope. When the "magic angle" of a sample material used as a standard is attained by varying the angular position of the sample holder, the coordinate position of the reference mark relative to a graduation or graduations on a reticle in the magnifying scope is noted. Thereafter, the spinning "magic angle" of a test material having similar nuclear properties to the standard is attained by returning the sample holder back to the originally noted coordinate position.
Beer, Stephen K. (Morgantown, WV); Pratt, II, Harold R. (Morgantown, WV)
An optical calibration apparatus is provided for calibrating and reproducing spinning angles in cross-polarization, nuclear magnetic resonance spectroscopy. An illuminated magnifying apparatus enables optical setting and accurate reproducing of spinning magic angles in cross-polarization, nuclear magnetic resonance spectroscopy experiments. A reference mark scribed on an edge of a spinning angle test sample holder is illuminated by a light source and viewed through a magnifying scope. When the magic angle of a sample material used as a standard is attained by varying the angular position of the sample holder, the coordinate position of the reference mark relative to a graduation or graduations on a reticle in the magnifying scope is noted. Thereafter, the spinning magic angle of a test material having similar nuclear properties to the standard is attained by returning the sample holder back to the originally noted coordinate position. 2 figs.
Beer, S.K.; Pratt, H.R. II.
Magnetism Highlights| Neutron Science | ORNL
Magnetism Magnetism SHARE Magnetism Highlights 1-5 of 5 Results ARCS maps collaborative magnetic spin behavior in iron telluride December 01, 2011 - Researchers have long thought that magnetism and superconductivity are mutually exclusive. The former typically involves localized atomic electrons. The latter requires freely propagating, itinerant electrons. Unexpected Magnetic Excitations in Doped Insulator Surprise Researchers October 01, 2011 - When doping a disordered magnetic insulator material with atoms of a nonmagnetic material, the conventional wisdom is that the magnetic interactions between the magnetic ions in the material will be weakened. Neutron Analysis Reveals Unique Atomic-Scale Behavior of "Cobalt Blue" September 01, 2011 - Neutron scattering studies of "cobalt blue," a
Superconductivity Superconductivity Research Highlights Superconductivity Archive New Neutron Studies Support Magnetism's Role in Superconductors Recent neutron scattering experiments give strong evidence that if superconductivity is related to a material's magnetic properties, the same mechanisms are behind both copper-based, high-temperature superconductors and the newly discovered iron-based superconductors. The research was performed at SNS and HFIR and the ISIS Facility at Rutherford Appleton Laboratory in England. (2010) Published Work: "Evolution of spin excitations into the superconducting state in FeTe1-xSex" Contact: Mark Lumsden Advances in Unconventional Iron-Based Superconductors The discovery of more diverse superconducting materials will lead to more
Brief Studying of Oil Crust Thickness Measurement by Gamma Ray Compton Scattering Approach
The relation between the scattering cross section and the scattering angle under different energy condition of the incident rays is analyzed. From Compton scattering total cross section, a formula of quasi-parallel incident gamma ray Compton scattering response function versus to thickness of oil crust target is derived and analyzed. Numerical fitting result shows that there exists cubic relation between response function of gamma ray and thickness of oil crust. Key words: Gamma ray, Compton scattering, oil crust
Mamatrishat, Mamat; Jie, Ding; Shiheng, Wang
Neutron Sciences at Oak Ridge National Laboratory
Research Research Find out how neutron scattering can benefit your research. Call for Proposals Proposals for beam time at HFIR and SNS will be accepted via the web-based proposal system until 11:59 a.m. EST, (NOON) Wednesday, February 26, 2014. Comprehensive phonon "map" offers direction for engineering new thermoelectric devices. Comprehensive phonon "map" offers direction for engineering new thermoelectric devices. High-pressure studies of rare earth material could lead to lighter, cheaper magnets High-pressure studies of rare earth material could lead to lighter, cheaper magnets Unfrozen mystery: H2O reveals a new secret Unfrozen mystery: H2O reveals a new secret Neutron scattering workshop promotes high-pressure research Neutron scattering workshop promotes high-pressure research.
Neutronic reactor
A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.
Wende, Charles W. J. (West Chester, PA)
Neutron source
A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.
Cason, J.L. Jr.; Shaw, C.B.
Charged-particle tracking for neutron-deuteron breakup
Particle tracking software has been developed to measure the energy of protons scattered in the breakup process d(n, np)n. The nd breakup experiment is performed at the Weapons Neutron Research facilities at Los Alamos ...
Boddy, Kimberly K
Capabilities of the CNCS Instrument | ORNL Neutron Sciences
in one day. A recent example is a study of the phonon spectra in PbTe, one of the leading thermoelectric materials. Using a combination of inelastic neutron scattering measurements...
Measurement of the free neutron-proton analyzing power and spin transfer parameters in the charge exchange region at 790 MeV
The free neutron-proton analyzing power and the spin transfer parameters (K/sub NN/, K/sub SS/, K/sub SL/, and K/sub LL/) were measured at the Los Alamos Meson Physics Facility at 790 MeV between 165/sup 0/ and 180/sup 0/ center of mass. A 40% polarized neutron beam incident on a liquid hydrogen target was used. The recoil protons were momentum analyzed with a magnetic spectrometer to isolate elastic scatters. A large solid angle carbon polarimeter was used to measure the proton polarization. The measurements are the first at this energy and are in basic agreement with pre-existing phase shift solutions. The proton-carbon analyzing power was measured between 500 and 750 MeV. An empirical fit to the proton-carbon analyzing power between 100 and 750 MeV was done.
Ransome, R.D.
Battery Studies Battery Studies A Wealth of New Battery Research at SNS and HFIR Technical Contacts: Xun-Li Wang, Ashfia Huq, Jung-Hyun Kim October 2010, Written by Carolyn Krause Neutron scattering, capable of looking deep inside the structures of materials used in technologies such as batteries and fuel cells, is a natural tool for research in energy storage and production. Several users of neutron scattering instruments at the SNS and HFIR presented details of their energy-related research to prospective scientific facility users attending the opening session of ORNL's User Week at SNS. Most of the energy-related research reported in the session dealt with batteries for electric and hybrid electric cars. Better batteries are also needed for storing excess electricity generated by wind and solar power so
Fast Proton Hopping in Ice Fast Proton Hopping in Ice Fast Proton Hopping in Ice (Ih) Confirmed by Quasi-Elastic Neutron Scattering "With these results, we have an experimental proof of fast proton hopping in ice," researcher says Research Contact: Alexander Kolesnikov June 2011, Written by Agatha Bardoel Protons (positive hydrogen ions) in an ice lattice have been "seen" to fast hop from one water molecule to another, using quasi-elastic neutron scattering at the SNS Backscattering Spectrometer, BASIS. This fundamental phenomenon that occurs at very low temperatures has important consequences for future investigations of proton conductivity in solids. The research could open the door to a new understanding of how electrolytes work in a system. Proton hopping in ice occurs when "extra" protons diffuse through
Alternatives to 3He for Neutron Detection for Homeland Security
Neutron detection is an essential aspect of interdiction of radiological threats for national security purposes, since plutonium, a material used for nuclear weapons, is a significant source of fission neutrons. Radiation portal monitoring systems, of which there are thousands deployed for homeland security and non-proliferation purposes, currently use 3He gas-filled proportional counters for detecting neutrons. Because of the high usage of 3He for neutron scattering science and national security, the supply has dwindled, and can no longer meet the demand. Consequently, a replacement technology for neutron detection is required in the very near future.
Kouzes, Richard T.; Conlin, Kenneth E.; Ely, James H.; Erikson, Luke E.; Kernan, Warnick J.; Lintereur, Azaree T.; Siciliano, Edward R.; Stephens, Daniel L.; Stromswold, David C.; Van Ginhoven, Renee M.; Woodring, Mitchell L.
Neutron/Proton Capture Neutron/Proton Capture Beam Line 13 Fuels Discovery Fever for Fundamental Physicists Research Contact: Geoff Greene June 2011, Written by Agatha Bardoel Serpil Kucuker Dogan (left) and Matthew Musgrave prepare a helium-3 cooling cell that is used to measure the angle at which the neutron beam strikes the liquid hydrogen sample. The simplest, most sensible " Big Bang" universe, theoretical physicists believe, would be one in which equal numbers of particles and antiparticles are formed in pairs. As the universe cools, most of these particles would encounter their antiparticles, and they would annihilate. "In many ways, the most reasonable universe would be one in which there is no matter," says the University of Tennessee's Dr. Geoff Greene.
Thermal neutron detection system
According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.
Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)
Atomic-Scale Behavior of "Cobalt Blue" Atomic-Scale Behavior of "Cobalt Blue" Neutron Analysis Reveals Unique Atomic-Scale Behavior of "Cobalt Blue" Research Contact: Gregory MacDougall ORNL News Release, September 2011, Media Contact: Bill Cabage Cobalt aluminate Just as cobalt blue's lustrous hue attracts artists and decorators, the antiferromagnetic properties of the responsible compound-cobalt aluminate-are attracting neutron scientists at DOE's Oak Ridge National Laboratory. Studies of magnetic interactions deep within the material's atomic structure may provide clues toward the development of energy-efficient technologies. (Light sconce image courtesy of B. Jefferson Bolender. Click image for high res version.) Neutron scattering studies of "cobalt blue," a compound prized by artists
HFIR History - ORNL Neutron Sciences
Home › Facilities › HFIR › History Home › Facilities › HFIR › History History of HFIR HFIR was constructed in the mid-1960s to fulfill a need for the production of transuranic isotopes (i.e., "heavy" elements such as plutonium and curium). Since then its mission has grown to include materials irradiation, neutron activation, and, most recently, neutron scattering. In 2007, HFIR completed the most dramatic transformation in its 40-year history. During a shutdown of more than a year, the facility was refurbished and a number of new instruments were installed, as well as a cold neutron source. The reactor was restarted in mid-May; it attained its full power of 85 MW within a couple of days, and experiments resumed within a week. Improvements and upgrades to HFIR include an overhaul of the
Directional neutron detectors for use with 14 MeV neutrons :fiber scintillation methods for directional neutron detection.
Current Joint Test Assembly (JTA) neutron monitors rely on knock-on proton type detectors that are susceptible to X-rays and low energy gamma rays. We investigated two novel plastic scintillating fiber directional neutron detector prototypes. One prototype used a fiber selected such that the fiber width was less than 2.1mm which is the range of a proton in plastic. The difference in the distribution of recoil proton energy deposited in the fiber was used to determine the incident neutron direction. The second prototype measured both the recoil proton energy and direction. The neutron direction was determined from the kinematics of single neutron-proton scatters. This report describes the development and performance of these detectors.
Sunnarborg, Duane A.; Peel, Justin D.; Mascarenhas, Nicholas; Mengesha, Wondwosen
Neutron Instruments Added at Oak Ridge
The neutron scattering facilities at Oak Ridge National Laboratory continue their development as new instruments are commissioned and join the user program at the Spallation Neutron Source and High Flux Isotope Reactor. More than 640 proposals were received for beam time during the January-May 2011 period on SNS and HFIR instruments with about half either being accepted or identified as alternates. The proposal call for the period June-December 2011, announced at http://neutrons.ornl.gov, will close February 23, 2011.
A nuclear reactor is described wherein horizontal rods of thermal- neutron-fissionable material are disposed in a body of heavy water and extend through and are supported by spaced parallel walls of graphite.
A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)
Fraas, A.P.; Mills, C.B.
A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)
Richmond, J.L.; Wells, C.E.
Neutron range spectrometer
A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.
Manglos, S.H.
Science Opportunities at ORNL's Neutron Sources
The Neutron Sciences Directorate at Oak Ridge National Laboratory (ORNL) operates two of the world's most advanced neutron scattering research facilities: the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). Our vision is to provide unprecedented capabilities for understanding structure and properties across the spectrum of biology, chemistry, physics, and engineering, and to stay at the leading edge of neutron science by developing new instruments, tools, and services. This talk will provide an update on the operations of the two research facilities and highlight the significant research that is emerging. For example, scientists from ORNL are at the forefront of research on a new class of iron-based superconductors based on experiments performed at the Triple-Axis Spectrometer at HFIR and ARCS at SNS. The complementary nature of neutron and x-ray techniques will be discussed to spark discussion among attendees.
Anderson, Ian [ORNL, SNS
Tables are presented of experimental differential neutron cross sections for the elastic scattering of neutrons by nuclei in the energy range of 0 to 15 Mev. Nuclear reactions induced by neutrons are also included, particularly those that are significant for reactor-type calculations. The tables include nuclei from H to Pu. (D.L.C.)
Howerton, R.J.
The New Munich Neutron Source FRM II: Overview and Uses for Biological Studies
Neutron Physics at NIST M. Arif 8th UCN Workshop St. Petersburg Moscow, Russia June 11-21, 2011 #12;NCNR Guide Hall 20 MW Reactor #12;Neutron Physics at the NCNR Beam Flux n cm-2 s-1 Peak Wavelength Facility Low Scatter Neutron Dosimeter Calibration Facility #12;December 31, 2012 Physics Physics Physics
Doster, Wolfgang
Neutron Repulsion
Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding how: a.) The Sun generates and releases neutrinos, energy and solar-wind hydrogen and helium; b.) An inhabitable planet formed and life evolved around an ordinary-looking star; c.) Continuous climate change - induced by cyclic changes in gravitational interactions of the Sun's energetic core with planets - has favored survival by adaptation.
Oliver K. Manuel
Iterative Methods for Neutron Transport Eigenvalue Problems
We discuss iterative methods for computing criticality in nuclear reactors. In general this requires the solution of a generalized eigenvalue problem for an unsymmetric integro-differential operator in six independent variables, modeling transport, scattering, ... Keywords: criticality, generalized eigenvalue problem, inexact inverse iteration, neutron transport, symmetry
Fynn Scheben; Ivan G. Graham
Californium Neutron Irradiation Facility
Californium Neutron Irradiation Facility. Summary: ... Cf irradiation facility (Photograph by: Neutron Physics Group). Lead Organizational Unit: pml. Staff: ...
Cold Neutron and Ultracold Neutron Sources
... Moderators � Solid Methane � CH 4 � CD 4 ... In a cold neutron flux with a continuous spectrum, more neutrons could ... Magneto-vibrational Scatt. + ...
Chapter 13 - NEUTRON AREA DETECTORS 1. NEUTRON ...
... The neutron peak corresponds to both reaction products being entirely absorbed in the ... 6. A fission chamber is a very low efficiency neutron detector ...
Mixed Legendre moments and discrete scattering cross sections for anisotropy representation
This paper deals with the resolution of the integro-differential form of the Boltzmann transport equation for neutron transport in nuclear reactors. In multigroup theory, deterministic codes use transfer cross sections which are expanded on Legendre polynomials. This modelling leads to negative values of the transfer cross section for certain scattering angles, and hence, the multigroup scattering source term is wrongly computed. The first part compares the convergence of 'Legendre-expanded' cross sections with respect to the order used with the method of characteristics (MOC) for Pressurised Water Reactor (PWR) type cells. Furthermore, the cross section is developed using piecewise-constant functions, which better models the multigroup transfer cross section and prevents the occurrence of any negative value for it. The second part focuses on the method of solving the transport equation with the above-mentioned piecewise-constant cross sections for lattice calculations for PWR cells. This expansion thereby constitutes a 'reference' method to compare the conventional Legendre expansion to, and to determine its pertinence when applied to reactor physics calculations. (authors)
Calloo, A.; Vidal, J. F.; Le Tellier, R.; Rimpault, G. [CEA, DEN, DER/SPRC/LEPh, F-13108 Saint-Paul-lez-Durance (France)
Deeply Virtual Neutrino Scattering
We investigate the extension of the deeply virtual Compton scattering process into the weak interaction sector.
Ales Psaker
A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.
Wigner, E.P.; Weinberg, A.W.; Young, G.J.
EIS-0247: Construction and Operation of the Spallation Neutron Source |
247: Construction and Operation of the Spallation Neutron 247: Construction and Operation of the Spallation Neutron Source EIS-0247: Construction and Operation of the Spallation Neutron Source SUMMARY The United States needs a high-flux, short- pulsed neutron source to provide its scientific and industrial research communities with a much more intense source of pulsed neutrons for neutron scattering research than is currently available. This source would assure the availability of a state-of-the-art neutron research facility in the United States in the decades ahead. This facility would be used to conduct research in areas such as materials science, condensed matter physics, the molecular structure of biological materials, properties of polymers and complex fluids, and magnetism. In addition to creating new scientific and
Polyelectrolyte biomaterials - Research Highlights | ORNL Neutron Sciences
Home › Research › Highlights › Polyelectrolyte biomaterials Home › Research › Highlights › Polyelectrolyte biomaterials Detecting the shape of polymer chains inside polyelectrolyte biomaterials Bio-SANS research for replacing cartilage in the spine and knees Research Contact: Marie Markarian Feb. 2012, Written by Agatha Bardoel Left: neutron scattering with contrast variation reveals the coil conformation of single polymer molecules in a blend of PSS and PDADMA. Contrast variation is achieved by deuteration of some of the PSS molecules (D-PSS) in the mixture. Right: The slope of the scattering curve exhibits a power law dependence Q-2, which is a characteristic signature of the random coil conformation of a polymer chain molecule. Left: neutron scattering with contrast variation reveals the coil conformation of single polymer molecules in a blend of PSS and PDADMA.
Cold-moderator scattering kernel methods
An accurate representation of the scattering of neutrons by the materials used to build cold sources at neutron scattering facilities is important for the initial design and optimization of a cold source, and for the analysis of experimental results obtained using the cold source. In practice, this requires a good representation of the physics of scattering from the material, a method to convert this into observable quantities (such as scattering cross sections), and a method to use the results in a neutron transport code (such as the MCNP Monte Carlo code). At Los Alamos, the authors have been developing these capabilities over the last ten years. The final set of cold-moderator evaluations, together with evaluations for conventional moderator materials, was released in 1994. These materials have been processed into MCNP data files using the NJOY Nuclear Data Processing System. Over the course of this work, they were able to develop a new module for NJOY called LEAPR based on the LEAP + ADDELT code from the UK as modified by D.J. Picton for cold-moderator calculations. Much of the physics for methane came from Picton`s work. The liquid hydrogen work was originally based on a code using the Young-Koppel approach that went through a number of hands in Europe (including Rolf Neef and Guy Robert). It was generalized and extended for LEAPR, and depends strongly on work by Keinert and Sax of the University of Stuttgart. Thus, their collection of cold-moderator scattering kernels is truly an international effort, and they are glad to be able to return the enhanced evaluations and processing techniques to the international community. In this paper, they give sections on the major cold moderator materials (namely, solid methane, liquid methane, and liquid hydrogen) using each section to introduce the relevant physics for that material and to show typical results.
Definition: Angle of incidence | Open Energy Information
Open Energy Info (EERE)
Angle of incidence Angle of incidence Jump to: navigation, search Dictionary.png Angle of incidence In reference to solar energy systems: the angle a ray of sun makes with a line perpendicular to a surface; for example, a surface directly facing the sun has an angle of incidence of zero, and a surface parallel to the sun (such as a sunrise striking a horizontal rooftop) has an angle of incidence of 90°. Sunlight with an incident angle of 90° tends to be absorbed, while lower angles tend to be reflected.[1][2] View on Wikipedia Wikipedia Definition Angle of incidence is a measure of deviation of something from "straight on", for example: in the approach of a ray to a surface, or the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.
DOE Science Showcase - Neutron Science Research from DOE Databases | OSTI,
DOE Science Showcase - Neutron Science Research from DOE Databases DOE Science Showcase - Neutron Science Research from DOE Databases Additional neutron science research in DOE Databases Information Bridge Neutron scattering research was pioneered in 1946 by ORNL's Clifford G. Shull, winner of 1994 Nobel Prize in Physics. Access Shull's early research records in Energy Citations Database. Neutron scattering research was pioneered in 1946 by ORNL's Clifford G. Shull, winner of 1994 Nobel Prize in Physics. Access Shull's early research records in Energy Citations Database. Energy Citations Database DOE R&D Accomplishments DOE R&D Project Summaries DOE Data Explorer DOepatents Researchers at DOE labs, including Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), and Oak Ridge National Laboratory
Review of Multi-messenger observations of neutron rich matter
At very high densities, electrons react with protons to form neutron rich matter. This material is central to many fundamental questions in nuclear physics and astrophysics. Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as the Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that uses parity violating electron scattering to measure the neutron radius of 208Pb. This has important implications for neutron stars and their crusts. We discuss X-ray observations of neutron star radii. These also have important implications for neutron rich matter. Gravitational waves (GW) open a new window on neutron rich matter. They come from sources such as neutron star mergers, rotating neutron star mountains, and collective r-mode oscillations. Using large scale molecular dynamics simulations, we find neutron star crust to be very strong. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. Finally, neutrinos from core collapse supernovae (SN) provide another, qualitatively different probe of neutron rich matter. Neutrinos escape from the surface of last scattering known as the neutrino-sphere. This is a low density warm gas of neutron rich matter. Neutrino-sphere conditions can be simulated in the laboratory with heavy ion collisions. Observations of neutrinos can probe nucleosyntheses in SN. We believe that combing astronomical observations using photons, GW, and neutrinos, with laboratory experiments on nuclei, heavy ion collisions, and radioactive beams will fundamentally advance our knowledge of compact objects in the heavens, the dense phases of QCD, the origin of the elements, and of neutron rich matter.
C. J. Horowitz
The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.
Anderson, H.L.
Building Energy Software Tools Directory : SunAngle Professional...
SunAngle Professional Suite Back to Tool SunAngle Excel screenshot SunAngle Java screenshot SunAngle technical manual...
Use of the WNR spallation neutron source at LAMPF to determine the absolute efficiency of a neutron scintillation detector
Prompt fission neutron spectrum measurements at the University of Massachusetts Lowell 5.5 MV Van de Graaff accelerator laboratory require that the neutron detector efficiency be well known over a neutron energy range of 100 keV to 20 MeV. The efficiency of the detector, has been determined for energies greater than 5.0 MeV using the Weapons Neutron Research (WNR) white neutron source at the Los Alamos Meson Physics Facility (LAMPF) in a pulsed beam, time-of-flight (TOF) experiment. Carbon matched polyethylene and graphite scatterers were used to obtain a hydrogen spectrum. The detector efficiency was determined using the well known H(n,n) scattering cross section. Results are compared to the detector efficiency calculation program SCINFUL available from the Radiation Shielding Information Center at Oak Ridge National Laboratory.
Staples, P.A.; Egan, J.J.; Kegel, G.H.R.; Woodring, M.L.; DeSimone, D.J. [University of Massachusetts, Lowell, MA (United States). Dept. of Physics and Applied Physics; Lisowski, P.W. [Los Alamos National Lab., NM (United States)
Methods for absorbing neutrons
A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.
Guillen, Donna P. (Idaho Falls, ID); Longhurst, Glen R. (Idaho Falls, ID); Porter, Douglas L. (Idaho Falls, ID); Parry, James R. (Idaho Falls, ID)
TABLE OF CONTENTS 2014 ORNL NEUTRON SCIENCES STRATEGIC PLAN Executive Summary Director's Message Introduction Neutron Scattering User Facilities Comparison with Leading International Neutron Facilities Strategic Planning and Research Community Involvement New Opportunities Science Priorities Introduction Quantum Materials Materials Synthesis and Performance Soft Molecular Matter Biosciences New and Upgraded Capabilities Enabling Technologies Sources Executing the Plan Strategic Timeline Appendices and Acronyms 3 6 17 55 43 51 59 9 3 EXECUTIVE SUMMARY 2014 ORNL NEUTRON SCIENCES STRATEGIC PLAN EXECUTIVE SUMMARY AND DIRECTOR'S MESSAGE * Optimizing existing instrumentation with targeted de-
Total Scattering Developments for Total Scattering ...
... Density Functional Theory Molecular Dynamics ... of nuclear scattering from different nuclei in a sample) Large when energy nuclei in a sample). ...
Nonrelativistic Description of Nucleon-Nucleus Scattering
Within the three-dimensional semiclassical approximation, an analytic expression is obtained for the amplitude of proton-nucleus scattering at intermediate energies of incident protons. The method for deriving this amplitude is based on the use of the high-energy approximation with distorted waves. In view of the short-range character of proton-nucleon interaction, the process of proton-nucleus scattering is represented as a series of single scattering events occurring on each individual nucleon. With the aid of the proposed mathematical formalism, a recursion relation is derived that makes it possible to express the nuclear form factor obtained within the distorted-wave method in terms of the sum of an infinite Born series. Parameters that characterize the distributions of protons and neutrons in the spherical nuclei {sup 40}Ca, {sup 48}Ca, {sup 90}Zr, and {sup 208}Pb and which include the width of the surface layer of nucleons and the root-mean-square radii of the proton-, neutron-, and nucleon-density distributions are determined from an analysis of the measured cross sections for the elastic scattering of 1-GeV protons, a modified Fermi function being employed for the nucleon-density distribution.
Mirabutalybov, M.M. [Azerbaijan State Petroleum Academy, pr. Azadlyg 20, Baku, 370010 (Azerbaijan)
Rayleigh Quotient Iteration in 3D, Deterministic Neutron Transport
Today's "grand challenge" neutron transport problems require 3-D meshes with billions of cells, hundreds of energy groups, and accurate quadratures and scattering expansions. Leadership-class computers provide platforms on which high-fidelity fluxes can be calculated. However, appropriate methods are needed that can use these machines effectively. Such methods must be able to use hundreds of thousands of cores and have good convergence properties. Rayleigh quotient iteration (RQI) is an eigenvalue solver that has been added to the Sn code Denovo to address convergence. Rayleigh quotient iteration is an optimal shifted inverse iteration method that should converge in fewer iterations than the more common power method and other shifted inverse iteration methods for many problems of interest. Denovo's RQI uses a new multigroup Krylov solver for the fixed source solutions inside every iteration that allows parallelization in energy in addition to space and angle. This Krylov solver has been shown to scale successfully to 200,000 cores: for example one test problem scaled from 69,120 cores to 190,080 cores with 98% efficiency. This paper shows that RQI works for some small problems. However, the Krylov method upon which it relies does not always converge because RQI creates ill-conditioned systems. This result leads to the conclusion that preconditioning is needed to allow this method to be applicable to a wider variety of problems.
Slaybaugh, R [University of Wisconsin; Evans, Thomas M [ORNL; Davidson, Gregory G [ORNL; Wilson, P. [University of Wisconsin
Electrochemical in-situ reaction cell for X-ray scattering, diffraction and spectroscopy
An electrochemical in-situ reaction cell for hard X-ray experiments with battery electrodes is described. Applications include the small angle scattering, diffraction, and near-edge spectroscopy of lithium manganese oxide electrodes.
Braun, Artur; Granlund, Eric; Cairns, Elton J.
Physics design of a cold neutron source for KIPT neutron source facility.
Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the meV energy range through scattering reactions in the moderator and reflector materials. However, the fraction of neutrons with energies less than 5 meV in a normal moderator spectrum is very low because of up-scattering caused by the thermal motion of moderator or reflector molecules. In order to obtain neutrons with energy less than 5 meV, cryogenically cooled moderators 'cold neutron sources' should be used to slow down the neutrons. These cold moderators shift the neutron energy spectrum down because the thermal motion of moderator molecules as well as the up-scattering is very small, which provides large gains in intensity of low energy neutrons, E < 5 meV. The accelerator driven subcritical facility is designed with a provision to add a cryogenically cooled moderator system. This cold neutron source could provide the neutrons beams with lower energy, which could be utilized in scattering experiment and material structures analysis. This study describes the performed physics analyses to define and characterize the cold neutron source of the KIPT neutron source facility. The cold neutron source is designed to optimize the cold neutron brightness to the experimental instruments outside the radial heavy concrete shield of the facility. Liquid hydrogen or solid methane with 20 K temperature is used as a cold moderator. Monte Carlo computer code MCNPX [4], with ENDF/B-VI nuclear data libraries, is utilized to calculate the cold neutron source performance and estimate the nuclear heat load to the cold moderator. The surface source generation capability of MCNPX code has been used to provide the possibility of analyzing different design configurations and perform design optimization analyses with reasonable computer resources. Several design configurations were analyzed and their performance were characterized and optimized.
Zhong, Z.; Gohar, Y.; Kellogg, R.; Nuclear Engineering Division
Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the meV energy range through scattering reactions in the moderator and reflector materials. However, the fraction of neutrons with energies less than 5 meV in a normal moderator spectrum is very low because of up-scattering caused by the thermal motion of moderator or reflector molecules. In order to obtain neutrons with energy less than 5 meV, cryogenically cooled moderators 'cold neutron sources' should be used to slow down the neutrons. These cold moderators shift the neutron energy spectrum down because the thermal motion of moderator molecules as well as the up-scattering is very small, which provides large gains in intensity of low energy neutrons, E neutron source could provide the neutrons beams with lower energy, which could be utilized in scattering experiment and material structures analysis. This study describes the performed physics analyses to define and characterize the cold neutron source of the KIPT neutron source facility. The cold neutron source is designed to optimize the cold neutron brightness to the experimental instruments outside the radial heavy concrete shield of the facility. Liquid hydrogen or solid methane with 20 K temperature is used as a cold moderator. Monte Carlo computer code MCNPX [4], with ENDF/B-VI nuclear data libraries, is utilized to calculate the cold neutron source performance and estimate the nuclear heat load to the cold moderator. The surface source generation capability of MCNPX code has been used to provide the possibility of analyzing different design configurations and perform design optimization analyses with reasonable computer resources. Several design configurations were analyzed and their performance were characterized and optimized.
Scattering by coupled resonating elements in air
Scattering by (a) a single composite scatterer consisting of a concentric arrangement of an outer N-slit rigid cylinder and an inner cylinder which is either rigid or in the form of a thin elastic shell and (b) by a finite periodic array of these scatterers in air has been investigated analytically and through laboratory experiments. The composite scatterer forms a system of coupled resonators and gives rise to multiple low frequency resonances. The corresponding analytical model employs polar angle dependent boundary conditions on the surface of the N-slit cylinder. The solution inside the slits assumes plane waves. It is shown also that in the low-frequency range the N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further approximations suggest a simple square root dependence of the resonant frequencies on the number of slits and this is confirmed by data. The observed resonant phenomena are associated with Helmholtz-like behaviour of the resonator for which the radius and width of the openings are much smaller than the wavelength. The problem of scattering by a finite periodic array of such coupled resonators in air is solved using multiple scattering techniques. The resulting model predicts band-gap effects resulting from the resonances of the individual composite scatterers below the first Bragg frequency . Predictions and data confirm that use of coupled resonators results in substantial insertion loss peaks related to the resonances within the concentric configuration. In addition, for both scattering problems experimental data, predictions of the analytical approach and predictions of the equivalent fluid layer approximations are compared in the low-frequency interval.
Anton Krynkin; Olga Umnova; Alvin Y. B. Chong; Shahram Taherzadeh; Keith Attenborough
Giant resonance study by 6li scattering
Nuclear incompressibility Knm is an important parameter in the nuclear matter equation of state (EOS). The locations of the isocalar giant monopole resonance (ISGMR) and giant dipole resonance (ISGDR) of nuclei are directly related to Knm and thus can give the most effective constraint on the value of the Knm. In order to determine Knm accurately, a systematic study of the ISGMR and ISGDR over a wide range of nuclei is necessary. Alpha inelastic scattering at small angles has been successfully used to study the ISGMR of heavy and medium nuclei where the monopole resonance is concentrated in a broad peak. For light nuclei (Aradioactive nuclei with inverse reactions using 6Li as a target. Data for elastic scattering of 240 MeV 6Li ions and inelastic scattering to low-lying states and giant resonances was taken for 24Mg, 28Si and 116Sn. A data analysis procedure was developed for double folding calculations. The optical potential parameters for 6Li + 24Mg, 6Li + 28Si and 6Li + 116Sn scattering systems were obtained by fitting elastic scattering data. Multipole analyses were carried out for inelastic scattering to high lying isoscalar giant resonances with multipolarities L=0 - 3. The results for the ISGMR and ISGQR are in agreement with those obtained with 240 MeV ? scattering, however the agreement for the ISGDR and HEOR is not so good, indicating the uncertainty in extracting these strengths. This work has shown that 240 MeV 6Li scattering is a viable way to study the ISGMR and ISGQR and can be particularly useful in rare isotope studies where 6Li can be used as the target.
Chen, Xinfeng
Joint Institute for Neutron Sciences | ornl.gov
Joint Institute for Neutron Sciences Joint Institute for Neutron Sciences SHARE Joint Institute for Neutron Sciences JINS is located on Chestnut Ridge within the 80-acre SNS site, part of Oak Ridge National Laboratory. The Joint Institute for Neutron Sciences (JINS) was founded as a collaborative effort between Oak Ridge National Laboratory (ORNL) and The University of Tennessee to promote the use of neutron scattering in various fields of research. Through worldwide collaborations between researchers of the biological and life sciences, energy sciences, polymer science, condensed matter physics and computational sciences, a synergistic consortium will be created at ORNL to elevate the field of neutron sciences to a new level of efficacy for industry, medicine and frontier research. The goal of JINS is to serve as a gateway for users of the Spallation
Mixed field dosimetry of epithermal neutron beams for boron neutron capture therapy at the MITR-II research reactor
During the past several years, there has been growing interest in Boron Neutron Capture Therapy (BNCT) using epithermal neutron beams. The dosimetry of these beams is challenging. The incident beam is comprised mostly of epithermal neutrons, but there is some contamination from photons and fast neutrons. Within the patient, the neutron spectrum changes rapidly as the incident epithermal neutrons scatter and thermalize, and a photon field is generated from neutron capture in hydrogen. In this paper, a method to determine the doses from thermal and fast neutrons, photons, and the B-10([ital n],[alpha])Li-7 reaction is presented. The photon and fast neutron doses are measured with ionization chambers, in realistic phantoms, using the dual chamber technique. The thermal neutron flux is measured with gold foils using the cadmium difference technique; the thermal neutron and B-10 doses are determined by the kerma factor method. Representative results are presented for a unilateral irradiation of the head. Sources of error in the method as applied to BNCT dosimetry, and the uncertainties in the calculated doses are discussed.
Rogus, R.D.; Harling, O.K.; Yanch, J.C. (Massachusetts Institute of Technology, Nuclear Reactor Laboratory, Cambridge, Massachusetts 02139 (United States))
Characterization of deep weathering and nanoporosity development in shale - a neutron study
We used small-angle and ultra-small-angle neutron scattering (SANS/USANS) to characterize the evolution of nanoscale features in weathering Rose Hill shale within the Susquehanna/Shale Hills Observatory (SSHO). The SANS/USANS techniques, here referred to as neutron scattering (NS), characterize porosity comprised of features ranging from approximately 3 nm to several micrometers in dimension. NS was used to investigate shale chips sampled by gas-powered drilling ('saprock') or by hand-augering ('regolith') at ridgetop. At about 20 m depth, dissolution is inferred to have depleted the bedrock of ankerite and all the chips investigated with NS are from above the ankerite dissolution zone. NS documents that 5--6% of the total ankerite-free rock volume is comprised of isolated, intraparticle pores. At 5 m depth, an abrupt increase in porosity and surface area corresponds with onset of feldspar dissolution in the saprock and is attributed mainly to peri-glacial processes from 15 000 years ago. At tens of centimeters below the saprock-regolith interface, the porosity and surface area increase markedly as chlorite and illite begin to dissolve. These clay reactions contribute to the transformation of saprock to regolith. Throughout the regolith, intraparticle pores in chips connect to form larger interparticle pores and scattering changes from a mass fractal at depth to a surface fractal near the land surface. Pore geometry also changes from anisotropic at depth, perhaps related to pencil cleavage created in the rock by previous tectonic activity, to isotropic at the uppermost surface as clays weather. In the most weathered regolith, kaolinite and Fe-oxyhydroxides precipitate, blocking some connected pores. These precipitates, coupled with exposure of more quartz by clay weathering, contribute to the decreased mineral-pore interfacial area in the uppermost samples. These observations are consistent with conversion of bedrock to saprock to regolith at SSHO due to: (1) transport of reactants (e.g., water, O{sub 2}) into primary pores and fractures created by tectonic events and peri-glacial effects; (2) mineral-water reactions and particle loss that increase porosity and the access of water into the rock. From deep to shallow, mineral-water reactions may change from largely transport-limited where porosity was set largely by ancient tectonic activity to kinetic-limited where porosity is changing due to climate-driven processes.
Jin, Lixin [ORNL; Rother, Gernot [ORNL; Cole, David R [ORNL; Mildner, David [ORNL; Duffy, Christopher S [ORNL; Brantley, Susan L [ORNL
Ultracold-neutron production in a pulsed-neutron beam line
We present the results of an ultracold neutron (UCN) production experiment in a pulsed-neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal can be overwhelmed by the large background associated with the scattering of the primary cold-neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-{sup 2}H{sub 2} is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O{sub 2}. In addition to setting the overall detection efficiency in the apparatus, UCN production data using solid {sup 2}H{sub 2} suggest that the UCN upscattering cross section is smaller than previous estimates, indicating the deficiency of the incoherent approximation widely used to estimate inelastic cross sections in the thermal and cold regimes.
Lavelle, C. M.; Liu, C.-Y.; Fox, W.; Manus, G.; McChesney, P. M.; Salvat, D. J.; Shin, Y.; Makela, M.; Morris, C.; Saunders, A.; Couture, A.; Young, A. R. [Physics Department, Indiana University, Bloomington, Indiana 47408 (United States); Physics Division, P25, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); LANSCE Division, Nuclear Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Physics Department, North Carolina State University, Raleigh, North Carolina 27695 (United States)
Meson production in high-energy electron-nucleus scattering
Experimental studies of meson production through two-photon fusion in inelastic electron-nucleus scattering is now under way. A high-energy photon radiated by the incident electron is fused with a soft photon radiated by the nucleus. The process takes place in the small-angle-Coulomb region of nuclear scattering. We expound the theory for this production process as well as its interference with coherent-radiative-meson production. In particular, we investigate the distortion of the electron wave function due to multiple-Coulomb scattering.
G�ran F�ldt
Contact ORNL Neutron Sciences
Sciences Organization Charts Neutron Sciences Directorate Associate Laboratory Director for Neutron Sciences, Kelly Beierschmitt Biology and Soft Matter Division Director, Paul...
A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.
Reardon, W.A.; Lennox, D.H.; Nobles, R.G.
Spallation Neutron Source | ORNL Neutron Sciences
Spallation Neutron Source SNS site, Spring 2012 The 80-acre SNS site is located on the east end of the ORNL campus and is about a three-minute drive from her sister neutron...
A measurement of. Delta. sigma. sub L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states
A measurement off {Delta}{sigma}{sub L}(np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. The results will help determine the isospin-zero (I = 0) scattering amplitudes, which are not well known above laboratory energies of 500 MeV, whereas the isospin-one (I = 1) amplitudes are fairly well-determined to 1 GeV. Data points were taken at the Los Alamos Meson Physics Facility (LAMPF) at Los Alamos, New Mexico, for five neutron beam energies: 484, 568, 634,720 and 788 MeV; they are the first in this energy range. Polarized neutrons were produced by charge-exchange of polarized protons on a liquid deuterium target (LD{sub 2}). Large-volume neutron counters detected the neutrons that passed through a polarized proton target. The counters subtended a range of solid angles large enough to allow extrapolation of the scattered neutrons to 0{degree}. Two modifications to the LAMPF accelerator system which were made for this work are described. They included a beam buncher,'' which modified the normal rf-time structure of the proton beam and allowed for the selection of peak-energy neutrons by time-of-flight means, and a computerized beam steering program, which reduced systematic effects due to beam motion at the LD{sub 2} target. The experimental values of {Delta}{sigma}{sub L}(np) are found to be consistent with other np data, including preliminary data from SIN and Saclay, but not with some results from Argonne which used a polarized proton beam and a polarized deuteron target. The I = 0 component was extracted from {Delta}{sigma}{sub L}(np) using existing pp data (I = 1), with the unexpected result that {Delta}{sigma}{sub L}(I = 0) was found to be essentially identical in shape to {Delta}{sigma}{sub L}(I = 1). The significance of this is not yet understood.
Beddo, M.E.
Literature survey of chemical analysis by thermal neutron induced capture gamma ray spectrometry
A brief discussion of the principles and techniques of chemical analysis by neutron capture gamma radiation is presented, and the widely scattered literature is collected into a single table arranged by element measured.
Gladney, E.S.
The E158 experiment at SLAC has made the first measurement of parity violation in electron-electron (Moeller) scattering. The authors report a preliminary result using 50% of the accumulated data sample for the right-left parity-violating cross-section asymmetry (A{sub PV}) in the elastic scattering of 45 and 48 GeV polarized electron beams with unpolarized electrons in a liquid hydrogen target. They find A{sub PV} = (-160 {+-} 21(stat.) {+-} 17(syst.)) {center_dot} 10{sup -9}, with a significance of 6.3{sigma} for observing parity violation. In the context of the Standard Model, this yields a measurement of the weak mixing angle, sin{sup 2} {theta}{sub W}{sup {ovr MS}} (Q{sup 2} = 0.026GeV{sup 2}) = 0.2379 {+-} 0.0016(stat.) {+-} 0.0013(syst.). They also present preliminary results for the first observation of a single-spin transverse asymmetry in Moeller scattering.
Woods, M
Biomolecular solution X-ray scattering at the National Synchrotron Light Source
In recent years there has been a growing interest in the application of X-ray scattering techniques to biomolecules in solution. At NSLS, a new undulatorbased beamline, X9, has been constructed to address the oversubscribed user demand for X-ray scattering. Beamline X9 has the capability to perform small/wide-angle X-ray scattering (SAXS/WAXS) all in one single instrument. This is accomplished by utilizing a vacuum sample/detector chamber that is an integral part of the SAXS scattering flight path. This vacuum chamber allows a WAXS detector to be positioned at a close distance from the sample, while not interfering with scattered X-rays at small angles from reaching the SAXS detector. A regular training program, the X9 workbench, has also been established to allow users to become familiar with beamline X9 for solution X-ray scattering. Keywords: SAXS; WAXS; beamline; proteins; DNA/RNA. 1.
Marc Allaire; Lin Yang
Reflected Neutron Effects in Multiplicity Measurements of Bare HEU Assemblies
In a passive multiplicity characterization of highly enriched uranium (HEU) assemblies, fission chains are initiated by the characteristically fast neutrons from spontaneous fission of {sup 238}U and {sup 235}U as well as cosmic-ray spallation neutrons. Active interrogation of HEU uses other physical mechanisms for starting chains by inducing fission from high-energy neutrons, high-energy gamma-rays, delayed neutrons, or thermal neutrons. In all cases a contribution to the initiation of fission chains is the reflection of neutrons that initially escape the assembly and re-enter it after undergoing some scattering. The reflected neutron flux is geometry dependent and a combination of fast and thermal energies. The reflected thermal neutron contribution occurs hundreds of microseconds after the beginning of the fission chain and can be distinguished from the cosmic-ray spallation neutrons unrelated to fission chains, resulting in an HEU detection signature with high signal-to-noise. However, the reflected thermal neutron flux can be eliminated with an efficient thermal neutron absorber to investigate reflected neutron effects. In this paper, active and passive multiplicity measurements with HEU oxide assemblies of up to 16 kg of fuel pins and HEU metal assemblies of up to five 18 kg storage castings are reported. Each case demonstrates the differences in HEU signature when a borated thermal neutron absorber is present and shows the various detectable signatures with 3He proportional counters, the standard detector for differential die-way and neutron multiplicity measurements, and liquid scintillators, a detector capable of operating on the timescale of fission chains.
McConchie, Seth M [ORNL; Hausladen, Paul [ORNL; Mihalczo, John T [ORNL
Souleymane Omar Diallo | ORNL Neutron Sciences
Souleymane Omar Diallo Souleymane Omar Diallo Quantum Condensed Matter Division Education Ph.D. Physics, University of Delaware, Newark, DE, USA (2007). BSc. Physics, Université Cadi-Ayyad, Marrakesh, Morocco (1999). Description of Research Dynamics of Water in Confinement, Proteins Dynamics, Porous Materials, Neutron and X-ray Scattering, Soft Condensed Matter Physics, Supefluidity and Superconductivity, Quantum Fluids and Solids, Ferroelectricity. Selected Publications J. Charmichael and S.O. Diallo, "A cryogenic high pressure cell for neutron scattering measurements of quantum fluids and solids", submitted Review of Scientific Instruments (2012) S.O. Diallo, E. Mamontov, S. Inagaki, Y. Fukushima, and N. Wada, "Enhanced Translational Dynamics of Water under Electric Field" Phys.
Direct three-dimensional coherently scattered x-ray microtomography
Purpose: It has been shown that coherently scattered x rays can be used to discriminate and identify specific components in a mixture of low atomic weight materials. The authors demonstrated a new method of doing coherently scattered x-ray tomography with a thin sheet of x ray. Methods: A collimated x-ray fan-beam, a parallel polycapillary collimator, and a phantom consisting of several biocompatible materials of low attenuation-based contrast were used to investigate the feasibility of the method. Because of the particular experimental setup, only the phantom translation perpendicular to the x-ray beam is needed and, thus, there is no need of Radon-type tomographic reconstruction, except for the correction of the attenuation to the primary and scattered x rays, which was performed by using a conventional attenuation-based tomographic image data set. The coherent scatter image contrast changes with momentum transfer among component materials in the specimen were investigated with multiple x-ray sources with narrow bandwidth spectra generated with anode and filter combinations of Cu/Ni (8 keV), Mo/Zr (18 keV), and Ag/Pd (22 keV) and at multiple scatter angles by orienting the detector and polycapillary collimator at different angles to the illuminating x ray. Results: The contrast among different materials changes with the x-ray source energy and the angle at which the image was measured. The coherent scatter profiles obtained from the coherent scatter images are consistent with the published results. Conclusions: This method can be used to directly generate the three-dimensional coherent scatter images of small animal, biopsies, or other small objects with low atomic weight biological or similar synthetic materials with low attenuation contrast. With equipment optimized, submillimeter spatial resolution may be achieved.
Cui Congwu; Jorgensen, Steven M.; Eaker, Diane R.; Ritman, Erik L. [Department of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street Southwest, Alfred Building 2-409, Rochester, Minnesota 55905 (United States)
Cross sections for electron scattering from magnesium
A B-spline R-matrix (close-coupling) method has been used to perform a systematic study of angle-differential cross sections for electron scattering from neutral magnesium. The calculations cover elastic scattering and excitation of the five excited states (3s3p) {sup 3,1}P{sup o}, (3s3d) {sup 1}D, (3s4s) {sup 1}S, and (3s4p) {sup 1}P{sup o}. A multiconfiguration Hartree-Fock method with nonorthogonal orbitals was employed for an accurate representation of the target wave functions. The close-coupling expansion for the collision problem included 37 bound states of neutral magnesium. Angle-differential cross sections are presented for incident electron energies from 10 to 100 eV. These results, as well as the corresponding angle-integrated cross sections, are compared with various experimental data and predictions from other close-coupling and distorted-wave calculations. In spite of a few remaining discrepancies, the overall agreement between our results and the experimental data is very satisfactory.
Zatsarinny, Oleg; Bartschat, Klaus; Gedeon, Sergey; Gedeon, Viktor; Lazur, Vladimir; Nagy, Elizabeth [Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311 (United States); Department of Theoretical Physics, Uzhgorod State University, Uzhgorod 88000 (Ukraine)
A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.
Wigner, E.P.; Young, G.J.
Landau damping effects on the scattering spin-asymmetry and channel preference in election-hole plasmas
The scattering spin-asymmetry and spin channel preference in electron collisions are investigated in electron-hole plasmas. It is found that the Landau damping effect enhances the scattering channel preference for the spin-singlet electron scattering and suppresses the spin-triplet electron scattering except the scattering angle {theta}={pi}/2. It is also found that the spin-singlet electron scattering decreases with an increase of the quantum shielding distance. In addition, the Landau damping effect on the spin-asymmetry parameter is found to be more significant in the intermediate domain of the quantum Debye length.
Jung, Young-Dae [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of) and Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407 (United States); Hong, Woo-Pyo [Department of Electronics Engineering, Catholic University of Daegu, Hayang 712-702 (Korea, Republic of)
Fundamental Physics Highlights | Neutron Science | ORNL
Fundamental Physics Fundamental Physics SHARE Fundamental Physics Highlights 1-3 of 3 Results Neutron experiments give unprecedented look at quantum oscillations October 23, 2012 - Researchers at the Department of Energy's Oak Ridge National Laboratory have found that nitrogen atoms in the compound uranium nitride exhibit unexpected, distinct vibrations that form a nearly ideal realization of a physics textbook model known as the isotropic quantum harmonic oscillator. Beam Line 13 Fuels Discovery Fever for Fundamental Physicists June 01, 2011 - Kucuker Dogan (left) and Matthew Musgrave prepare a helium-3 cooling cell that is used to measure the angle at which the neutron beam strikes the liquid hydrogen sample. Fast Proton Hopping in Ice (Ih) Confirmed by Quasi-Elastic Neutron
Environment scattering in GADRAS.
Radiation transport calculations were performed to compute the angular tallies for scattered gamma-rays as a function of distance, height, and environment. Green's Functions were then used to encapsulate the results a reusable transformation function. The calculations represent the transport of photons throughout scattering surfaces that surround sources and detectors, such as the ground and walls. Utilization of these calculations in GADRAS (Gamma Detector Response and Analysis Software) enables accurate computation of environmental scattering for a variety of environments and source configurations. This capability, which agrees well with numerous experimental benchmark measurements, is now deployed with GADRAS Version 18.2 as the basis for the computation of scattered radiation.
Thoreson, Gregory G.; Mitchell, Dean James; Theisen, Lisa Anne; Harding, Lee T.
The Versatile Neutron Imaging Instrument at SNS | ORNL Neutron...
The Versatile Neutron Imaging Instrument at SNS VENUS: Neutron imaging to advance energy efficiency VENUS: Neutron imaging to advance energy efficiency. As its name indicates,...
Neutron Energy Spectrum Measurements with a Compact Liquid Scintillation Detector on EAST
A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and gamma-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI (Tl) gamma-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.
Xi Yuan; Xing Zhang; Xufei Xie; G. Gorini; Zhongjing Chen; Xingyu Peng; Jinxiang Chen; Guohui Zhang; Tieshuan Fan; Guoqiang Zhong; Liqun Hu; Baonian Wan
2010 Neutron Review: ORNL Neutron Sciences Progress Report
During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology, and operations. Some topics discussed are: (1) HFIR and SNS Experiments Take Gordon Battelle Awards for Scientific Discovery - Battelle Memorial Institute presented the inaugural Gordon Battelle Prizes for scientific discovery and technology impact in 2010. Battelle awards the prizes to recognize the most significant advancements at national laboratories that it manages or co-manages. (2) Discovery of Element 117 - As part of an international team of scientists from Russia and the United States, HFIR staff played a pivotal role in the discovery by generating the berkelium used to produce the new element. A total of six atoms of ''ununseptium'' were detected in a two-year campaign employing HFIR and the Radiochemical Engineering Development Center at Oak Ridge National Laboratory (ORNL) and the heavy-ion accelerator capabilities at the Joint Institute for Nuclear Research in Dubna, Russia. The discovery of the new element expands the understanding of the properties of nuclei at extreme numbers of protons and neutrons. The production of a new element and observation of 11 new heaviest isotopes demonstrate the increased stability of super-heavy elements with increasing neutron numbers and provide the strongest evidence to date for the existence of an island of enhanced stability for super-heavy elements. (3) Studies of Iron-Based High-Temperature Superconductors - ORNL applied its distinctive capabilities in neutron scattering, chemistry, physics, and computation to detailed studies of the magnetic excitations of iron-based superconductors (iron pnictides and chalcogenides), a class of materials discovered in 2008. This research is yielding new insights into the relationship between magnetism and superconductivity and has established several key features of this family of high-temperature superconducting (HTS ) materials: the maximum magnetic field at which they can function, the nature of the electrons involved in the superconductivity, the dependence of the properties upon chemical substitution, and the character of the magnetic fluctuations in the material. The results suggest that despite important differences between these materials and the HTS copper oxides, a universal mechanism may be responsible for the unconventional superconductivity. (4) Coal Sequestration Research: A New Home for Greenhouse Gases - One possibility for slowing down the increasing levels of carbon dioxide (CO{sub 2}) in the atmosphere is to capture the gas in natural underground features such as coal seams. Critical to the feasibility of this technology is determining how much CO{sub 2} can be stored, no method for which has been found - until now. (5) Accelerator Reliability Passes 92% - In December 2010, SNS set a new record for itself when the accelerator ran at 1 MW with 100% reliability. Target Performance Exceeds All Expectations - The mercury target used at SNS is the first of its kind. During the design and planning for SNS, many people were skeptical that the target would work. In 2010, it was confirmed that the target was working not only well but much better than anyone would have imagined. (6) Changing the World of Data Acquisition - Researchers at SNS are starting to benefit from event-based data analysis. Event data mode captures and stores an individual data set for every single neutron that strikes a detector - precisely when and where the neutron is detected. This technique provides numerous advantages over traditional methods. Event data mode allows researchers to process their data at the highest resolution possible with no loss of data. This method of data collection provides a much more efficient way for users to gather data a
Bardoel, Agatha A [ORNL; Counce, Deborah Melinda [ORNL; Ekkebus, Allen E [ORNL; Horak, Charlie M [ORNL; Nagler, Stephen E [ORNL; Kszos, Lynn A [ORNL
Using polarized Neutrons for elastic and dynamic studies on protein systems
We report about measurements at the new Neutron Resonance Spin Echo (NRSE) instrument RESEDA (FRM II, Munich). We have performed polarization analysis, providing information about the fraction of neutrons scattered without and with spin flip at the sample. From comparison with the resolution function measured on a standard sample, the dynamics of the incoherent fraction is detected by NRSE measurements at low temperatures.
Haeussler, W. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, D-85747 Garching (Germany); Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany); Kindervater, J. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, D-85747 Garching (Germany)
Design of the Mechanical Parts for the Neutron Guide System at HANARO
The research reactor HANARO (High-flux Advanced Neutron Application ReactOr) in Korea will be equipped with a neutron guide system, in order to transport cold neutrons from the neutron source to the neutron scattering instruments in the neutron guide hall near the reactor building. The neutron guide system of HANARO consists of the in-pile plug assembly with in-pile guides, the primary shutter with in-shutter guides, the neutron guides in the guide shielding room with dedicated secondary shutters, and the neutron guides connected to the instruments in the neutron guide hall. Functions of the in-pile plug assembly are to shield the reactor environment from nuclear radiation and to support the neutron guides and maintain them precisely oriented. The primary shutter is a mechanical structure to be installed just after the in-pile plug assembly, which stops neutron flux on demand. This paper describes the design of the in-pile assembly and the primary shutter for the neutron guide system at HANARO. The design of the guide shielding assembly for the primary shutter and the neutron guides is also presented.
Shin, J. W.; Cho, Y. G.; Cho, S. J.; Ryu, J. S. [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)
The electric dipole moment of the nucleon from simulations at imaginary vacuum angle theta
We compute the electric dipole moment of proton and neutron from lattice QCD simulations with N_f=2 flavors of dynamical quarks at imaginary vacuum angle theta. The calculation proceeds via the CP odd form factor F_3. A novel feature of our calculation is that we use partially twisted boundary conditions to extract F_3 at zero momentum transfer. As a byproduct, we test the QCD vacuum at nonvanishing theta.
R. Horsley; T. Izubuchi; Y. Nakamura; D. Pleiter; P. E. L. Rakow; G. Schierholz; J. Zanotti
Neutron Science TeraGrid Gateway
The unique contributions of the Neutron Science TeraGrid Gateway (NSTG) are the connection of national user facility instrument data sources to the integrated cyberinfrastructure of the National Science FoundationTeraGrid and the development of a neutron science gateway that allows neutron scientists to use TeraGrid resources to analyze their data, including comparison of experiment with simulation. The NSTG is working in close collaboration with the Spallation Neutron Source (SNS) at Oak Ridge as their principal facility partner. The SNS is a next-generation neutron source. It has completed construction at a cost of $1.4 billion and is ramping up operations. The SNS will provide an order of magnitude greater flux than any previous facility in the world and will be available to all of the nation's scientists, independent of funding source, on a peer-reviewed merit basis. With this new capability, the neutron science community is facing orders of magnitude larger data sets and is at a critical point for data analysis and simulation. There is a recognized need for new ways to manage and analyze data to optimize both beam time and scientific output. The TeraGrid is providing new capabilities in the gateway for simulations using McStas and a fitting service on distributed TeraGrid resources to improved turnaround. NSTG staff are also exploring replicating experimental data in archival storage. As part of the SNS partnership, the NSTG provides access to gateway support, cyberinfrastructure outreach, community development, and user support for the neutron science community. This community includes not only SNS staff and users but extends to all the major worldwide neutron scattering centers.
Lynch, Vickie E [ORNL; Chen, Meili [ORNL; Cobb, John W [ORNL; Kohl, James Arthur [ORNL; Miller, Stephen D [ORNL; Speirs, David A [ORNL; Vazhkudai, Sudharshan S [ORNL
New Approach to Measure Lattice Strains under Torsional Shear ...
... torsional loading, using recent data obtained at ORNL-NRSF2 in conjunction ... Small Angle Neutron Scattering and Neutron Diffraction of HANARO Reactor.
Directorate Organization | ORNL Neutron Sciences
ORNL Neutron Sciences Directorate The Neutron Sciences Directorate (NScD) manages and operates the Spallation Neutron Source and the High Flux Isotope Reactor, two of the world's...
Publications from Research Conducted at IMAGING | ORNL Neutron Sciences
Publications from Research Conducted at IMAGING Publications from Research Conducted at IMAGING 2013 Publications Barnett A. K., Cox M. N., Crow L., Diawara Y., Funk L. L., Hayward Jason P., Menhard K., Sedov V. N., "A high count rate neutron beam monitor for neutron scattering facilities", IEEE Transactions on Nuclear Science 60, 668-670 (2013). Bingham P., Polsky Y., Anovitz L., "Neutron imaging for geothermal energy systems", Proceedings of the SPIE 8661, 86610K (2013). Kang M., "Hydraulic properties of variably-saturated porous media determined using quantitative neutron radiography", University of Tennessee , (2013). Kang M., Bilheux H. Z., Voisin S., Cheng C. L., Perfect E., Horita J., Warren J. M., "Water calibration measurements for neutron radiography: application to water content quantification in porous media", Nuclear
Use of ultracold neutrons for condensed-matter studies
Ultracold neutrons have such low velocities that they are reflected by most materials at all incident angles and can be stored in material bottles for long periods of time during which their intrinsic properties can be studied in great detail. These features have been mainly used for fundamental-physics studies including the detection of a possible neutron electric dipole moment and the precise determination of neutron-decay properties. Ultracold neutrons can also play a role in condensed-matter studies with the help of high-resolution spectrometers that use gravity as a strongly dispersive medium for low-velocity neutrons. Such studies have so far been limited by the low intensity of existing ultracold-neutron sources but could be reconsidered with more intense sources, which are now envisaged. This report provides a broad survey of the properties of ultracold neutrons (including their reflectivity by different types of samples), of ultracold-neutron spectrometers that are compared with other high-resolution instruments, of results obtained in the field of condensed matter with these instruments, and of neutron microscopes. All these subjects are illustrated by numerous examples.
Michaudon, A.
Precomputed atmospheric scattering
We present a new and accurate method to render the atmosphere in real time from any viewpoint from ground level to outer space, while taking Rayleigh and Mie multiple scattering into account. Our method reproduces many effects of the scattering of light, ...
Eric Bruneton; Fabrice Neyret
ICANS-XIV. The fourteenth meeting of the international collaboration on advanced neutron sources.
The meeting began with a reception on Sunday evening. Monday's plenary sessions included status reports on the four operating spallation neutron sources, IPNS, ISIS, KENS, and the Lujan Center; on the INR source under construction at Troitsk; on the IBR-2 pulsed reactor at Dubna; and on proposals for five new installations. We also heard reports on spin-off activities: the ASTE tests (liquid mercury target tests at the AGS accelerator at Brookhaven), the ACoM activities (developments aimed to provide cold moderators suitable for high-power pulsed sources), and the International Workshop on Cold Moderators for Pulsed Neutron Sources, held in September 1997 at Argonne. Jose Alonso and Bob Macek delivered enlightening invited talks overviewing linear accelerators and rings for spallation neutron sources. The rest of the meeting was devoted to targets and moderators and to instrumentation in a normal rotation of ICANS topics. There were altogether 84 oral reports and 23 poster presentations. On Tuesday and on Wednesday morning, we divided into separate series of sessions on Instrumentation and on Targets and Moderators. In the first, we had reports and discussions on instrumentation and techniques, on computer software, on instrument suites, and on new instruments and equipment. In the second series were sessions on liquid target systems, on solid target systems, on neutron production and target physics, on moderator physics and performance, and on target and moderator neutronics. The Tuesday evening meetings went on until 10:00, making for a 14-hour working day. That everyone willingly endured the long hours is a credit to the dedication of the attendees. On Wednesday afternoon, we boarded buses for the 1-hour trip to Argonne, where attendees toured IPNS and the Advanced Photon Source. Returning to Starved Rock, we enjoyed boat rides on the Illinois River and then a barbecue banquet dinner at the Lodge. All day Thursday and Friday morning, the attendees, in small working groups, discussed next-generation powder diffractometers, critical heat flux limitations on solid targets, monte carlo instrument simulation, prospects for high- and low-energy spectroscopy, small angle scattering and reflectometry, and the roles of solid and liquid targets in high-power pulsed spallation sources. Representatives of the laboratories participating in ICANS met Thursday evening to discuss the outcome of ICANS XIV and to decide whether, where, and when the next meeting would take place. They agreed to meet again in about 2 years in Japan. After the lunch break on Friday, the working group chairs presented the findings of their groups to the participants in a final plenary session, and the meeting adjourned with good feelings of accomplishment.
Carpenter, J. M., ed.; Tobin, C. A., ed.
Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle
Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light) and atomic force microscopy (AFM) experiments have been carried out on aerogels at dierent steps of densi
Demouchy, Sylvie