Monte Carlo energy spectrum matching method for SiPM-based EJ254 plastic scintillator detector calibration

Abstract

Accurate energy measurement is the precondition for the application of plastic scintillator-based spectrometers in space exploration missions, and appropriate energy calibration methods are very important for plastic scintillators. At the same time, the energy resolution is a key factor in evaluating the performance of spectrometers. In this paper, an energy calibration method that can be used for plastic scintillators is proposed, and the energy resolution calibration results were also obtained in the process. The key of the method is to focus on the accurate energy prediction of the reference points in the Compton Continuum by using the Monte Carlo energy spectrum matching method. In the calibration process, the experimental measurements and Monte Carlo simulations of 22Na and 137Cs were carried out, and the shapes of the obtained spectra were matched by a certain energy resolution model. By shape matching, the Monte Carlo simulations provided energies of reference points, and the experiments provided their corresponding channel numbers. Then the parameters of the energy calibration model were obtained by fitting with multiple reference points’ paired data. Moreover, the backscattering experiments with 131I, 137Cs, and 232Th sources were executed to equivalently provide monoenergetic electrons to verify the energy calibration and energy resolution model parameters obtained for the EJ254 spectrometer. The accuracy was high in the energy range of 341∼2381.6 keV, the maximum bias of the energy was −4.7 keV (@2381.6 keV), and the maximum bias of the energy resolution model was 4.7% (@341 keV).