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T: Fachverband Teilchenphysik

T 108: Niederenergie-Neutrinophysik/Suche nach Dunkler Materie 3

T 108.1: Gruppenbericht

Dienstag, 28. Februar 2012, 16:45–17:05, ZHG 102

Latest results from the CRESST-II Dark Matter Search — •Raimund Strauss — Physik-Department E15, Technische Universität München, D-85747 Garching, Germany

CRESST-II is searching for Dark Matter WIMPs via elastic scattering off atomic nuclei in scintillating CaWO₄ target crystals. CRESST has completed more than 730 kg days of data taking in 2011.

The CRESST target crystals are operated as cryogenic calorimeters at millikelvin temperatures and read out by transition edge sensors. Each interaction in CaWO₄ produces a phonon signal in the target crystal and also a light signal that is measured by a secondary cryogenic calorimeter, allowing a very efficient discrimination between electron recoils from radioactive e/γ background and nuclear recoils. Moreover, to some extent, the different types of recoiling nuclei (O, Ca, W) can be distinguished.

We will report on the latest data, collected with eight detector modules. The data has shown a considerable number of events in our signal region. Since this large number of events is not consistent with the known sources of background in our experiment, we will discuss the compatibility of this excess of events with a possible WIMP-signal. Furthermore we will present the several improvements aimed at a reduction of the overall background level which are being implemented for the next data taking.