Method for converting in-situ gamma ray spectra of a portable Ge detector to an incident photon flux energy distribution based on Monte Carlo simulation

ADVANCED NUCLEAR INSTRUMENTATION AND DETECTION

Method for converting in-situ gamma ray spectra of a portable Ge detector to an incident photon flux energy distribution based on Monte Carlo simulation

Boubaker ASKRI，

Adel TRABELSI，

Brahim BACCARI

Nuclear Science and Techniques

Vol.19, No.6

pp.358-364

Published in print 20 Dec 2008

DOI：10.1016/S1001-8042(09)60019-1

CLC：TL817,TL814,O242.2

43201

A matrix stripping method for the conversion of in-situ gamma ray spectrum, obtained with portable Ge detector, to photon ﬂux energy distribution is proposed. The detector response is fully described by its stripping matrix and full absorption efficiency curve. A charge collection efficiency function is introduced in the simulation to take into account the existence of a transition zone of increasing charge collection after the inactive Ge layer. Good agreement is obtained between simulated and experimental full absorption efficiencies. The characteristic stripping matrix is determined by Monte Carlo simulation for different incident photon energies using the Geant4 toolkit system. The photon ﬂux energy distribution is deduced by stripping the measured spectrum of the partial absorption and cosmic ray events and then applying the full absorption efficiency curve. The stripping method is applied to a measured in-situ spectrum. The value of the absorbed dose rate in air deduced from the corresponding ﬂux energy distribution agrees well with the value measured directly in-situ.

Monte Carlo simulationGe detectorGamma radiationGeant4Stripping

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