Mainz 2012 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 63: Astroteilchenphysik

HK 63.6: Talk

Friday, March 23, 2012, 15:15–15:30, RW 3

Determining the reflectivity of PTFE in the VUV — •Karen Bokeloh — IKP, WWU Münster

In the hunt for dark matter the XENON collaboration searches for weakly interacting massive particles (WIMPS) by detecting their recoil from Xenon nuclei in a dual phase time-projection chamber (TPC). The ratio between the emitted light S1 and charge - the latter is converted into a second light signal S2 by electroluminescence - allows to discriminate nuclear recoils as caused by WIMPS or neutrons against electron recoils, the main background stemming from γs and electrons. For this separation it is essential that the complete primary light signal S1, that intrinsically is very low in intensity, is collected from the entire of the TPC with high efficiency. PTFE panels are implemented as boundaries of the TPC for two purposes - as electric insulator it is used to place wires for the electric field shaping and as reflector for the vacuum-UV light emitted in the Xenon scintillation process.

The reflection properties of the PTFE used in the Xenon100 experiment are not known in detail. In addition studies need to be conducted to evaluate the reflection properties of different low radioactivity PTFE samples as well as their mechanical and chemical treatment for use in the successor experiment Xe1t. Therefore, an ultrahigh vacuum reflection chamber has been designed and commissioned with a wavelength selective VUV light source. First measurements to show the functionality of the experiment will be presented. This work has been supported by DFG (for XENON100, GZ: WE1 843/7-1) and BMBF (for XENON1T, GZ: 05A11PM1).