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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:23 |
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Conference: Bucharest University Faculty of Physics 2012 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
GEANT 4 study of the contribution of coherent scattering in gamma-ray spectrometry
Authors:
Al. CHIROSCA, O. SIMA
Affiliation:
Faculty of Physics, University of Bucharest
E-mail
alecasndru.chirosca@gmail.com
Keywords:
Monte Carlo simulation; GEANT 4; coherent scattering; gamma-ray spectrometry; germanium detectors
Abstract:
he application of Monte Carlo simulation to the computation of the efficiency calibration curve of high purity germanium detectors is constantly expanding. This is especially true in the case of volume sources, for which the experimental calibration is difficult, expensive or even impossible. The routine application of Monte Carlo simulation requires the development of specific purpose, fast computer codes, including variance reduction techniques and approximations. However the quality of the approximations should be thoroughly evaluated before the implementation in the code. In this context in the present work the contribution of coherent scattering to spectrum and to full energy peak efficiency for a volume gamma ray source is studied by GEANT 4 simulation of a realistic experimental set up. The quality of the approximation of neglecting this contribution is evaluated as a function of photon energy. In the case of n-type HPGe detectors the approximation is very good above 50 keV. Because the useful energy range of p-type detectors is practically above 50 keV, for these detectors the approximation is always very good. By neglecting coherent scattering in the computation of the full energy peak efficiency it is possible to replace the interactions in the source with a transmission factor, evaluated analytically. This procedure is much faster than the full simulation of the interactions and its implementation in a simulation code contributes to a significant reduction of the computation time.
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