A new coplanar-grid high-pressure xenon gamma-ray spectrometer

Abstract

High-pressure xenon (HPXe) gas is a desirable radiation detection medium for many reasons, including its large atomic number, high density, low mean energy to produce an electron-ion pair, and the ability to produce devices with large detection volumes. While past work in HPXe has produced relatively successful detectors with energy resolution at 662 keV as good as approximately 2% FWHM, an expected limitation of these chambers in field operation is resolution degradation due to the vibration of their Frisch grids. Progress on a detector without a Frisch grid is reported in this submission; it is expected that the proposed anode design will provide competitive energy resolution with minimal degradation from mechanical vibration. Simulations accounting for charge carrier statistics, changes in the charge induced on the anode as a function of interaction location, and electronic noise predict a best-case energy resolution of 2.3% FWHM at 662 keV. Experimental data is compared with these simulations.