2D peak fitting for the analysis of radioxenon beta gamma spectra

Atmospheric traces of radioactive xenon, in particular $$^{131m}{\text {Xe}}$$ , $$^{133}{\text {Xe}}$$ , $$^{133m}{\text {Xe}}$$ and $$^{135}{\text {Xe}}$$ , can provide “smoking gun” evidence to classify underground nuclear fission reactions. Current software used to quantify isomer concentrations relies on a Region of Interest (ROI) method to sort beta-gamma coincidence counts. This experiences errors when classifying nuclides, especially with metastable nuclides, due to the difficulty of deconvoluting overlapping ROIs and accounting for shifts in detector calibration over time. To address this uncertainty, our technique mathematically models the distinctive peaks in an isomer’s beta-gamma spectrum. The function representations are then fitted to measured spectra to determine the concentrations of the primary isomers in the sample. From this proof-of-concept, we hope to create a more precise and accurate system to detect nuclear fission reactions.