Preparation of Measurement Sources of Archive Xenon Samples for HPGe γ Spectrometer in Radionuclide Verification

The radionuclide network of the International Monitoring System (IMS) for verification of the comprehensive nuclear-test-ban treaty (CTBT) comprises of 80 particulate stations and 40 co-located noble gas stations, and 16 radionuclide laboratories. The suspicious samples detected by the IMS radionuclide station will be further evaluated at the certified radionuclide laboratories. Therefore, it is expected that they could analyze the archive xenon samples by HPGe γ spectrometry or β-γ coincidence spectrometry. To improve the xenon monitoring ability，the Installation and Certification Group (ICG) of the IMS Division organized the LABS XENON EXERCISE in 2007. ICG distributed archive xenon samples from stations to participated laboratories during the exercise. In the process of detection of the xenon isotopes activity by HPGe γ spectrometer, the xenon sample must be transferred from the archive bottle to a special measurement cell. Based on the principle that xenon was adsorbed by activated charcoal, then desorbed by heating and pumped by diaphragmatic pump, four CTBT archive xenon samples were transferred in 2007. The xenon transfer efficiencies were measured by gas chromatograph. The results show that the transfer efficiencies are all about 80%.