Reflectance dependence of polytetrafluoroethylene on thickness for xenon scintillation light

TL;DR

This study investigates how the reflectance of PTFE, used in xenon-based detectors, varies with thickness near 178 nm, finding no significant change between 1 mm and 9.5 mm thickness.

Contribution

The paper provides experimental data showing PTFE reflectance near 178 nm is independent of thickness between 1 mm and 9.5 mm, aiding detector design optimization.

Findings

PTFE reflectance remains constant across tested thicknesses.

Thinner PTFE walls can be used without sacrificing reflectance.

Results support design of more compact xenon detectors.

Abstract

Many rare event searches including dark matter direct detection and neutrinoless double beta decay experiments take advantage of the high VUV reflective surfaces made from polytetrafluoroethylene (PTFE) reflector materials to achieve high light collection efficiency in their detectors. As the detectors have grown in size over the past decade, there has also been an increased need for ever thinner detector walls without significant loss in reflectance to reduce dead volumes around active noble liquids, outgassing, and potential backgrounds. We report on the experimental results to measure the dependence of the reflectance on thickness of two PTFE samples at wavelengths near 178 nm. No change in reflectance was observed as the thickness of a cylindrically shaped PTFE vessel immersed in liquid xenon was varied between 1 mm and 9.5 mm.