  XENON1T recently reported an excess of low-energy electron recoil events that
may be attributable to either new physics or to the radioactive decay of
tritium. It is likely that hydrogen is not be effectively removed by the hot
zirconium getters deployed in the detector. Cosmogenic activation of the xenon
underground is found to be insufficient to describe the observed excess,
although gases diffusing out of detector materials from cosmogenic activation
on surface may contribute. Changes in the operation of gas purification systems
for XENON1T and other liquid nobel gas detectors could both confirm the tritium
hypothesis and remove it from the detector.
