Compact Beta-Gamma Radioxenon Detection System with Improved Energy Resolution Using PIPS Detector

The monitoring of four radioxenon isotopes stands out as a key technology employed in detecting underground nuclear tests. In support of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), we develop and calibrate a novel radioxenon detection system based on beta-gamma coincidence, utilizing NaI(Tl) and silicon detectors for gamma and beta radiation detection. To assess its performance, the prototype detection system undergoes rigorous testing with Rn-222 and Xe-131m sources. A Ho-166m source is employed for energy calibration and performance evaluation of the silicon detector. In this study, we aim to investigate the utility of these materials and methods for a radioxenon detection system to achieve higher energy resolution while minimizing memory effects compared to conventional systems that employed plastic scintillator detectors. Our results demonstrate a significantly improved energy resolution of 7.8% (factor of similar to 3 x compared to plastic detectors) at the 129 keV conversion electron peak of Xe-131m. The improved system is a foundation for the development of operational systems with optimized geometry for the discrimination of radioxenon isotopes.