Reflectance of polytetrafluoroethylene for xenon scintillation light

Abstract

Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet wavelength region (λ=175 nm) where the reflecting properties of PTFE are not sufficiently known.In this work we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Fluoropolymers, namely ETFE, FEP and PFA were also measured. * Electronic address: claudio@lipc.fis.uc.pt

Ionization and scintillation of nuclear recoils in gaseous xenon

“…The walls were taken to be 100% reflective and the back reflector to be 79% reflective. Though these values are not consistent with the expected PTFE reflectivity in xenon gas (from [24] expected to be 50-60%), they properly reproduced the linear geometric dependence of S1. The source was modeled by emitting neutrons from a single point behind the lead block in a random direction, accompanied by a 4.4 MeV gamma ray also emitted in a random direction.…”

“…The presence of the TPB provided about a factor of 2 increase in light collection efficiency and was essential to observing the low S1 signals produced by nuclear recoils discussed in Section 3. This can be attributed to the combination of several factors including a high UV to visible conversion efficiency of about 80% at 170 nm [23], the increased reflectivity of PTFE at wavelengths of $ 400 nm ( 4 95% at normal incidence) over wavelengths of $ 170 nm (about 60% at normal incidence) [24], and increased PMT quantum efficiency at higher wavelengths.…”

Calibration, event reconstruction, data analysis, and limit calculation for the LUX dark matter experiment

“…This correction is small, on average 3% for top array PMTs and 1% for The degeneracy between the reflectivity of the Teflon and the absorption length for photons in the liquid can be seen, with each having similar effects on the reduction in the light collected. As the former asymptotes to ∼96%, a reasonable value [57], the latter approaches infinity.…”

Liquid noble gas detectors for low energy particle physics

“…Recently, there have been new efforts to determine the reflectivity profiles of some materials of interest for detector construction at the xenon emission wavelength [171,166,172]; some results are shown on the right panel of Figure 16. Figure 16.…”