Abstract The Large Underground Xenon (LUX) experiment operates at the Sanford
Underground Research Facility to detect nuclear recoils from the hypothetical Weakly
Interacting Massive Particles (WIMPs) on a liquid xenon target. Liquid xenon typically
contains trace amounts of the noble radioactive isotopes 85 Kr and 39 Ar that are not
removed by the in situ gas purification system. The decays of these isotopes at
concentrations typical of research-grade xenon would be a dominant background for a …