Simulation study of scintillation crystal photocoupling with SiPM for gamma spectrometry

Abstract Background: The silicon photomultiplier (SiPM) is a new type of photo detector consisting of avalanche photodiode arrays operated in Geiger mode. Its photocoupling performance with scintillation crystal is helpful for gamma spectrometry. Purpose: This study aims to provide a reliable tool for the design of scintillation detector photocoupling with SiPM to achieve effective gamma spectrometry with the GEANT4 code. Methods: GEANT4 toolkit is used to simulate NaI(TI) and LaBr₃:10%Ce³⁺ scintillation crystal detect 662-keV γ-ray photocoupling with SiPM by building a complete Monte Carlo model of a scintillator includes ionizing particle and optical photon transport. Energy resolution of 662-keV gamma spectrum is modified with the contribution of dark current noise amplified by the electronic system and statistical fluctuation of optical photon absorbed by avalanche photodiode of SiPM which was previously illuminated with monochromatic LED light. Results: Simulation results show that energy resolution of 662-keV gamma spectrum is in accordance with the result of experimental measurement. A group of parameters (Pr, s) which corresponded to scintillation crystal intrinsic energy resolution is obtained simultaneously. Conclusion: The GEANT4 simulation of NaI(TI) and LaBr₃:10%Ce³⁺ scintillation crystals photocoupling with SiPM for 662-keV γ-ray spectrometry results consistently with experimental energy spectrum, and confirms the reliability and rationality of material properties and parameters which set in GEANT4 toolkit. (authors)