Radioxenon calibration, quality control, and intercomparison exercises

The Idaho National Laboratory (INL, USA), serves as a quality control laboratory for the Comprehensive Test Ban Treaty Organization. Unfortunately, INL lost its primary source of traceable ¹³³Xe materials when the National Institute of Standards and Technology (NIST, USA) stopped producing this standard reference material. To address this gap, INL collaborated with the National Physical Laboratory (NPL, UK) in 2017 and 2018 through interlaboratory comparison experiments to validate INL's¹³³Xe calibration. Following successful completion of these intercomparisons, two additional intercomparisons were performed in 2020 and 2021, incorporating a second radionuclide (^131mXe) and three additional CTBTO affiliated analysis laboratories: Pacific Northwest National Laboratory (PNNL, USA), the Atomic Weapons Establishment (AWE, UK), and the Swedish Defense Research Agency (FOI, Sweden). Intercomparison results from all four exercises are presented and discussed.