A new algorithm for estimating radioxenon concentrations

A new algorithm (Xcounts) is introduced for estimating the activity concentrations of the xenon isotopes ^131mXe, ^133mXe, ¹³³Xe, and ¹³⁵Xe using beta-gamma coincidence data. The algorithm simultaneously estimates the decay counts associated with the four xenon isotopes, background, and radon in contrast to the net-counts method that uses sequential residual removal to account for background and interferences. Calibration data for background counts are determined from gas-background measurements and simulation. In Xcounts, the false positive count rates for ^131mXe and ^133mXe are lower than those for ¹³³Xe and ¹³⁵Xe. This algorithm appears to reliably detect the metastable isotopes at lower activity levels than the net-counts method and have similar performance for the other isotopes.