Quartz fluorescence backgrounds in xenon particle detectors

TL;DR

This paper investigates the origin of delayed photon noise in liquid xenon detectors, identifying UV-induced fluorescence of quartz windows as the main source, which impacts low-threshold dark matter and neutrino experiments.

Contribution

It provides the first comprehensive experimental evidence linking quartz fluorescence to delayed photon noise in xenon detectors.

Findings

Delayed photon noise follows scintillation pulses with a power law profile.

UV-induced fluorescence of quartz windows is the dominant noise source.

Identifies a potential mitigation strategy for low-background experiments.

Abstract

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.