Simulation study of energy resolution of the high-pressure xenon gamma-ray spectrometer

High-pressure xenon (HPXe) ionization chamber is a high-energy-resolution radiation detector for gamma spectrometry with excellent physical properties. It has a wide range of operation temperatures, excellent radiation resistance, and long-life performance. Energy resolution is an important parameter of an HPXe gamma-ray spectrometer and has been investigated by scientists through experimental methods for years. However, in previous researches, there are few simulations on energy resolution of different ionization chamber structures. In this paper, three simulation tools are used to simulate the energy resolution of the HPXe spectrometer. Monte Carlo simulation software PHITS and finite element analysis software ANSYS are used to establish the model of the HPXe ionization chamber with a shielding grid. Garfield++ is adopted to obtain the output signal for analyzing the energy resolution. The energy resolution under different gas components and shielding grid structures are simulated. Results show that when the gamma-ray energy is 662 keV, the deviation between the simulated energy resolution obtained in this paper and the expected theoretical value 0.6% reported in the document Dmitrenko et al. (1986) is 13.05%. Besides, the experimental energy resolution of the HPXe gamma-ray spectrometer made by MEPHI (Dmitrenko et al., 2008) is about 2% at 662keV. Therefore, the value of simulated result in this paper is between the experimental result of MEPHI and the theoretical value, and closer to the theoretical value, which means that the simulation method proposed in this paper has high credibility.