Single channel beta–gamma coincidence system for radioxenon measurement using well-type HPGe and plastic scintillator detectors

In order to improve detection sensitivity for radioxenon isotopes, a new single channel beta–gamma coincidence system has been developed. The system combines a well-type High-purity Germanium (HPGe) detector to measure gamma or X radiation and a plastic scintillator detector to obtain electron radiation. A 133Xe sample has been produced and the radioactive concentration was determined with length-compensated method based on three internal gas proportional counters. The performance of system has been checked by measuring 133Xe sample with and without coincidence. The coincidence detection efficiency of 81 keV gamma-ray from decay of 133Xe was calibrated to be 0.34 (1±2.4%), and the Minimum detectable activity (MDA) of the beta–gamma coincidence system for 133Xe was determined to be 1.8 mBq after one day of measurement.