On the use of 127Xe standards for the quality control of CTBTO noble gas stations and support laboratories

127Xe has a longer half-life than 131mXe, it can be easily purely produced and it is present in the environment at very low level. For these reasons, 127Xe is supposed to be a convenient quality control radionuclide for remote noble gas stations of the International Monitoring System (IMS) network. As CEA/DAM has recently developed two new photon/electron setups for low-level detection of 131mXe, 133mXe, 133Xe and 135Xe, we took the opportunity to test these setups for the measurement of a 127Xe standard. The results and a detailed description of these measurements are presented in this paper. They illustrate the complexity of 127Xe decay, emitting simultaneously several γ, X-rays, conversion electrons and Auger electrons; this results in highly summated coincidence spectra. The measurements performed provide precise electron energy calibration of the setups. The count rate of electrons in coincidence with iodine Kα X-rays was found to be surprisingly low, leading to the study of electron-gated photon spectrum. Finally, a comparison of three photon/electron coincidence spectra obtained with three different setups is given. The use of 127Xe as a standard for energy calibration of IMS noble gas station is possible, but it appears to be quite complicated for efficiency check of noble gas station equipped with β/γ detectors.