Münster 2011 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 6: Astroteilchenphysik I
HK 6.1: Vortrag
Montag, 21. März 2011, 14:00–14:15, A-1
First Results of the XENON100 Experiment — •Karen Bokeloh — Institut für Kernphysik, WWU Münster
The Xenon100 experiment uses a dual phase time projection chamber (TPC) to search for Weakly Interacting Massive Particle (WIMP) signals that can be detected and separated from background by their nuclear recoil signature. In the 62kg of liquid xenon scintillation light (S1) and free electrons are produced at the interaction point. The electrons are drifted by an applied field and cause an additional scintillation signal (S2) in the gaseous phase. The ratio between the 2 signals is used to discriminate against electron recoil signatures with an efficiency of 99%. 3 dimensional position reconstruction allows to use the self-shielding properties of xenon. Only the regions not in contact with any other materials are used for the dark matter analysis.
Strong background reduction is achieved by a passive layered shielding in the Gran Sasso underground laboratory (Italy) and by an active LXe layer of nearly 100 kg surrounding the TPC. Furthermore, a consequent selection of low background material has been a major step to achieve a reduced background level.
In a first commissioning run of 11.2 d of effective data the total background level achieved was 2 orders of magnitude lower than the one measured in the preceding Xenon10 experiment. In a fiducial volume of 40 kg no dark matter candidate event has been observed, resulting in a best upper limit for WIMP masses lower than 80 GeV/c2 (Phys. Rev. Lett. 105, 131302).