Optimization through simulation for the triple layer phoswich simultaneous beta gamma detector upgrade

A simulation tool has been developed using the Geant4 toolkit to simulate a phoswich single channel beta gamma coincidence detection system consisting of three layers of different scintillation materials: BC400, CsI and BGO. Monte Carlo simulation techniques are powerful tools for investigating the performance of radiation detectors. Geant4 is a simulation toolkit that can realistically model optical photon transport for scintillation detectors. This paper describes a Monte Carlo program based on the Geant4 toolkit that has been developed to optimize the geometry of the new version of the simultaneous beta gamma triple layer phoswich scintillation detector. In particular, the optimal length of two layers composing a triple layer phoswich detector is investigated in the work presented. The program presented in this paper implements the modeling of radiation transport and light collection when the detector is exposed to four isotopes of xenon: ¹³³Xe, ^133mXe, ^131mXe and ¹³⁵Xe. The organization of the program is outlined and the result obtained is the performance comparison of several detector layer geometries. This article shows how the different detector layer geometry options correlate to the performance of the simultaneous beta gamma detector. The detection efficiency and spectrometric performance for each one of the four radio xenon isotopes of the derived optimal detector geometry are analyzed. The results are presented and compared with state of the art simultaneous beta gamma detectors.