Experimental validation of absolute full energy peak efficiency and energy resolution of NaI(Tl), CsI(Tl), BGO, YAP(Ce) and CeBr3 scintillation detectors modeled with Monte Carlo codes

Abstract

Gamma ray spectroscopy has been used extensively for advanced studies in nuclear medicine, industry, and scientific research. Progress in modern high speed computers has allowed the development of sophisticated Monte Carlo simulation codes which can accurately model the time and energy response of gamma spectroscopy detectors and estimate performance parameters. The purpose of this work is to study results from simulation of scintillation detectors for gamma spectroscopy applications. Simulations were performed for three state-of-the-art Monte Carlo transport programs, OpenMC, Geant4 and MCNPX. For each, a model accurately approximating the geometry, dimensions and materials corresponding to the scintillators in real gamma spectroscopy experiments was created. Simulations were run for five different types of inorganic scintillation detectors – NaI(Tl), CsI(Tl), BGO, YAP(Ce) and CeBr₃ - for a wide range of incident gamma ray energies from 32 keV to 1408 keV. The gamma rays chosen correspond to well-known energies from commonly available radionuclide calibration sources, namely ²⁴¹Am, ²²Na, ¹³³Ba, ¹⁵²Eu, ¹³⁷Cs and ⁶⁰Co. Common detector performance parameters were extracted for each simulation program, including absolute full energy peak efficiency and energy resolution. Estimates from simulations of the latter two parameters were compared to experimental data for several gamma sources under the same or very similar conditions, including varying source-to-detector distance to validate the simulation models and the performance of the different simulation codes.