In the Underground Nuclear Explosions Signatures Experiment (UNESE) radioactive 37Ar and 127Xe were used as tracers in subsurface migration experiments. As part of the experiment, methods were developed to quantify 127Xe via ß-? coincidence spectroscopy. Later examination of the results highlighted a weakness of this analysis method in samples with no 127Xe present, so a reanalysis of samples was performed to identify those which were falsely identified as having 127Xe present. Ongoing work to develop a new analysis method with targeted regions of interest is also described.
Measurements were also performed to quantify the concentration of 127Xe and 37Ar which were injected as part of UNESE Phase 2. A best value for the concentration of 37Ar and 127Xe was determined and reported here for use in future analyses of the UNESE Phase 2 results.