It has been known for almost a decade that delayed photon noise with a power law time profile follows scintillation pulses in liquid xenon particle detectors. The origin of the noise has remained unknown, and in the past two years, has become an overwhelming background for low-threshold dark matter searches aimed at O(10) GeV dark matter particle masses, as well as measurements of coherent neutrino-nucleus scattering of 8B solar neutrinos. We have performed a comprehensive series of tests in a small liquid xenon cell at LBL, from which we conclude that the dominant component of this delayed photon noise is due to UV-induced fluorescence of quartz photosensor windows.
@article{arxiv.2505.08067,
title = {Quartz fluorescence backgrounds in xenon particle detectors},
author = {P. Sorensen and R. Gibbons},
journal= {arXiv preprint arXiv:2505.08067},
year = {2025}
}