# IDM2016

17-22 July 2016
Master Cutlers Hall
Europe/London timezone

## Measurement of the absolute reflectance of PTFE immersed in liquid xenon

19 Jul 2016, 14:40
20m
Venue: Cutlers' Main Hall (First Floor); Chair: Darren Grant; Session Manager: David Woodward ()

### Speaker

Francisco Neves (LIP - Laboratório de Instrumentação e Física Experimental de Partículas)

### Description

The response of a liquid xenon (LXe) detector based on scintillation is strongly dependent on the light collection efficiency, which in turn is critically dependent on the reflectance of the surfaces that surround the active volume. To improve the light collection in WIMP-search detectors using LXe as the sensitive medium, the active volume is usually surrounded by polytetrafluoroethylene (PTFE) reflector panels, used due to its very high bi-hemispherical reflectance (BHR) -- even at the short wavelength ($\lambda=178\,\text{nm}$) scintillation light of LXe. Data are available in the literature for the reflectance of PTFE in gas or in vacuum for wavelengths above $175\,\text{nm}$ (up to $2500\,\text{nm}$). Nevertheless, extrapolations using these data for the reflectance of PTFE when immersed in LXe are systematically lower than those obtained indirectly by comparing Monte Carlo simulations with the calibration data from detectors such as LUX, ZEPLIN-II and XENON-10. In this work, which contributed to the overall R&D effort towards the LUX-ZEPLIN (LZ) experiment, we present experimental results obtained with a dedicated setup for the absolute reflectance of three different PTFE samples (including the material used in LUX) when immersed in LXe. These results confirm that very high BHR values ($\geq97$%) can be achieved, enabling very low energy thresholds in these detectors.

### Primary author

Francisco Neves (LIP - Laboratório de Instrumentação e Física Experimental de Partículas)

### Co-authors

Alexandre Lindote (LIP - Laboratório de Instrumentação e Física Experimental de Partículas) Andrei Morozov (LIP - Laboratório de Instrumentação e Física Experimental de Partículas) Claudio Silva (LIP - Laboratório de Instrumentação e Física Experimental de Partículas) Isabel Lopes (LIP - Laboratório de Instrumentação e Física Experimental de Partículas) Vladimir Solovov (LIP - Laboratório de Instrumentação e Física Experimental de Partículas)

### Presentation Materials

 Slides
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