with a rest mass, particle radiation Cathode rays Crookes tube Cathode-ray tube, a phosphor-coated anode Atom polarization and electron polarization Stern–Gerlach experiment Ionizing radiation Ionizing radiation includes rays of "particles" as well as rays of "waves". Especially X-rays and gamma rays transfer enough energy in non-thermal, (single-) collision processes to separate electron(s) from an atom. Particle and ray flux Bubble chamber Cloud chamber Dosimeter, a technical device realizes different working principles. Geiger counter Ionisation chamber Microchannel plate detector Photographic plate Photostimulable phosphor plate Proportional counter Scintillation counter, Lucas cell Semiconductor detector Identification and content This could include chemical substances, rays of any kind, elementary particles, and quasiparticles. Many measurement devices outside this section may be used or at least become part of an identification process. For identification and content concerning chemical substances, see also Analytical chemistry, List of chemical analysis methods, and List of materials analysis methods. Substance content in mixtures, substance identification Carbon dioxide sensor chromatographic device, gas chromatograph separates mixtures of substances. Different velocities of the substance types accomplish the separation. Colorimeter absorbance, and thus concentration Gas detector Gas detector in combination with mass spectrometer, mass spectrometer identifies the chemical composition of a sample on the basis of the mass-to-charge ratio of charged particles. Nephelometer or turbidimeter Oxygen sensor (= lambda sond) Refractometer, indirectly by determining the refractive index of a substance. Smoke detector Ultracentrifuge, separates mixtures of substances. In a force field of a centrifuge, substances of different densities separate. pH: Concentration of protons in a solution pH meter Saturated calomel electrode Humidity Hygrometer the density of water in air Lysimeter the balance of water in soil Human senses and human body Sight Brightness: photometry Photometry is the measurement of light in terms of its perceived brightness to the human eye. Photometric quantities derive from analogous radiometric quantities by weighting the contribution of each wavelength by a luminosity function that models the eye's spectral sensitivity. For the ranges of possible values, see the orders of magnitude in: illuminance, luminance, and luminous flux. Photometers of various kinds: Lux meter for measuring illuminance, i.e. incident luminous flux per unit area Luminance meter for measuring luminance, i.e. luminous flux per unit area and unit solid angle Light meter, an instrument used to set photographic exposures. It can be either a lux meter (incident-light meter) or a luminance meter (reflected-light meter), and is calibrated in photographic units. Integrating sphere for collecting