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Gamma-ray spectroscopy is the qualitative study of the energy spectra of gamma-ray sources, such as in the nuclear industry, geochemical investigation, and astrophysics. Gamma-ray spectrometry , on the other hand, is the method used to acquire a quantitative spectrum measurement.
A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of gamma-ray spectra for scientific and technical use is called gamma spectroscopy , and gamma-ray spectrometers are the instruments which observe ...
Gamma spectroscopy is the study of the energetic transitions in atomic nuclei, which are generally associated with the absorption or emission of gamma rays. As in optical spectroscopy (see Franck–Condon effect) the absorption of gamma rays by a nucleus is especially likely (i.e., peaks in a "resonance") when the energy of the gamma ray is the ...
The high-purity solid state germanium (HPGe) detectors used in gamma-ray spectroscopy have a typical size of a few centimeters in diameter and a thickness ranging from a few centimeters to a few millimeters. For detectors of such a size, gamma rays may Compton scatter out of the detector's volume before they deposit their entire energy.
Eight PMTs are used to collect light, and the total counting rate is kept below 10 kHz to avoid pilup contributions. [8] [9] Around the TAS there is a 19 cm thick shielding box made of four layers: polythene, lead, copper and aluminium. The box absorbs most external radiation, including neutrons, cosmic rays and background from the facility. [10]
Just as a gun recoils when a bullet is fired, conservation of momentum requires a nucleus (such as in a gas) to recoil during the emission or absorption of a gamma ray. If a nucleus at rest emits a gamma ray, the energy of the gamma ray is slightly less than the natural energy of the transition, but in order for a nucleus at rest to absorb a gamma ray, the gamma ray's energy must be slightly ...
In fact, gamma rays can be used as a probe to observe the effects of interactions between a nucleus and its electrons and those of its neighbors. This is the basis for Mössbauer spectroscopy, which combines the Mössbauer effect with the Doppler effect to monitor such interactions.
A gamma ray cross section is a measure of the probability that a gamma ray interacts with matter. The total cross section of gamma ray interactions is composed of several independent processes: photoelectric effect, Compton (incoherent) scattering, electron-positron pair production in the nucleus field and electron-positron pair production in the electron field (triplet production).