Development of gamma-spectrum data generation method by Monte Carlo simulation

A digital twin system for a gamma-ray spectrometer was developed using the Geant4 Monte Carlo simulation toolkit and a dedicated novel methodology. The model system was verified to accurately represent the intrinsic characteristics of gamma-ray detection systems: not only Gaussian energy broadening caused by energy resolution, but also count loss and coincidence summing caused by the dead time and charge collection time, respectively, of the detector system. In order to represent the time-related phenomena, the results of the Monte Carlo simulation were printed out in list-mode data rather than (as in existing previous studies) as a simple energy spectrum. The list-mode data were then post-processed considering the characteristics of the gamma-ray detection systems. The model system was verified by comparison with real-world experimental data using radiation sources ( 137 Cs and 60 Co) and a high-purity germanium detector, the results of which showed that the spectra generated by the model well matched the experimental spectra throughout the entire energy range (0–3 MeV), with correlations of 94.3 and 94.6% for 137 Cs and 60 Co, respectively.