Low level noble gas measurements in the field and laboratory in support of the Comprehensive Nuclear-Test-Ban Treaty

Over 300 daily environmental radioxenon samples were analyzed using French developed SPALAX for automatic sample preparation including high-resolution γ-spectrometry. The 133Xe sensitivity was significantly better than 1 mBq/m3 (specified criterion for Comprehensive Nuclear-Test-Ban Treaty verification). Radioxenon analysis was extended to include the X-ray region by improved detector window, sample cell design, efficiency calibration, line shape fitting and background analysis. The resulting analysis offers a 4–16 fold improvement in sensitivity for 133mXe and 131mXe, respectively.