A model of the reflection distribution in the vacuum ultra violet region

TL;DR

This paper presents a three-component reflection model for VUV light on fluoropolymers, validated with xenon scintillation data, useful for simulating and analyzing scintillation detectors with high reflectance properties.

Contribution

It introduces a comprehensive reflection model incorporating a specular spike, a specular lobe, and a diffuse lobe, tailored for VUV light and fluoropolymer surfaces.

Findings

The model accurately describes xenon scintillation light reflection on PTFE.

Measured total reflectance for PTFE is about 70% at normal incidence in vacuum.

Reflectance can reach up to 100% in contact with liquid xenon.

Abstract

A reflection model with three components, a specular spike, a specular lobe and a diffuse lobe is discussed. This model was successfully applied to describe reflection of xenon scintillation light (175 nm) by PTFE and other fluoropolymers and can be used for Monte Carlo simulation and analysis of scintillation detectors. The measured data favors a Trowbridge-Reitz distribution function of ellipsoidal micro-surfaces. The intensity of the coherent reflection increases with increasing angle of incidence, as expected, since the surface appears smoother at grazing angles. The total reflectance obtained for PTFE is about 70% for VUV light at normal incidence in vacuum and estimated to be up to 100% in contact with liquid xenon.