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Please use this identifier to cite or link to this item: http://apo.ansto.gov.au/dspace/handle/10238/4147

Title: The determination of the efficiency of a Compton suppressed HPGe detector using Monte Carlo simulations
Authors: McNamara, AL
Heijnis, H
Fierro, D
Reinhard, MI
Keywords: Efficiency
Radiation detectors
CALIBRATION
MONTE CARLO METHOD
Gamma spectroscopy
GERMANIUM
Issue Date: 1-Apr-2012
Publisher: ELSEVIER
Citation: McNamara, A.L., Heijnis, H., Fierro, D., Reinhard, M.I., (2012). The determination of the efficiency of a Compton suppressed HPGe detector using Monte Carlo simulations. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY, 106, 1-7.
Abstract: Compton suppressed high-purity germanium (HPGe) detector is well suited to the analysis of low levels of radioactivity in environmental samples. The difference in geometry, density and composition of environmental calibration standards (e.g. soil) can contribute to excessive experimental uncertainty to the measured efficiency curve. Furthermore multiple detectors, like those used in a Compton suppressed system, can add complexities to the calibration process. Monte Carlo simulations can be a powerful complement in calibrating these types of detector systems, provided enough physical information on the system is known. A full detector model using the Geant4 simulation toolkit is presented and the system is modelled in both the suppressed and unsuppressed mode of operation. The full energy peak efficiencies of radionuclides from a standard source sample is calculated and compared to experimental measurements. The experimental results agree relatively well with the simulated values (within similar to 5 - 20%). The simulations show that coincidence losses in the Compton suppression system can cause radionuclide specific effects on the detector efficiency, especially in the Compton suppressed mode of the detector. Additionally since low energy photons are more sensitive to small inaccuracies in the computational detector model than high energy photons, large discrepancies may occur at energies lower than similar to 100 keV. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.jenvrad.2011.10.017
http://apo.ansto.gov.au/dspace/handle/10238/4147
ISSN: 0265-931X
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