A plastic scintillator gas detector designed for radioxenon isotopes measurement with a high electron detection efficiency

Four CTBT relevant radioxenon isotopes, namely 131mXe, 133mXe, 133Xe and135Xe, play a key role for underground nuclear test monitoring. In order to improve the detection sensitivity of radioxenon, a plastic scintillator detector, which was used as the β detector as well as the gas sample cell, was developed. Then the performances of the plastic scintillator detector were tested. The hermetic seal was quite good with the leakage rate less than 1×10−4Pa⋅L/s. The energy resolution of 129.4 keV conversion electron associated with 131mXe was determined to be 27%. A significantly high detection efficiency of β-particle was achieved. The detection efficiencies of 346.4 keV β-particle for133Xe and 129.4 keV conversion electron for 131mXe are 0.966 ± 0.029 and 0.988 ± 0.005 respectively. The memory effect was found to be less than 3%. The plastic scintillator detector provides adequate foundation of β-γ(HPGe) coincidence measurement method research of high resolution and high sensitivity.