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T: Fachverband Teilchenphysik

T 22: Detektorsysteme 1

T 22.5: Talk

Monday, March 24, 2014, 12:05–12:20, GFH 01-721

Radiopurity of CaWO₄ Crystals — •Andrea Münster¹, Andreas Ertl¹, Achim Gütlein¹, Jean-Côme Lanfranchi¹, Felix Neumann¹, Walter Potzel¹, Sabine Roth¹, Stefan Schönert¹, Moritz von Sivers¹, Raimund Strauss², Stephan Wawoczny¹, Michael Willers¹, Marc Wüstrich², and Andreas Zöller¹ — ¹Physik Department E15, TU München, 85748 Garching — ²Max-Planck-Institut für Physik, 80805 München

The direct Dark Matter search experiment CRESST uses scintillating CaWO₄ single crystals as targets for possible WIMP recoils. The observed background is mainly due to intrinsic radioactive impurities of the crystals the activity of which can be determined by investigating α decays. In the past CaWO₄ crystals were produced by external suppliers. Since 2011 the crystal laboratory of TU Munich is able to grow CaWO₄ crystals to better meet the requirements of CRESST and to prepare for the future ton-scale multi-material experiment EURECA. The radiopurity of the raw materials is measured by γ-spectroscopy with low-background germanium detectors. Furthermore, first TUM-grown crystals were investigated in low-temperature test measurements and are now taking data in the current CRESST run. In this talk we will discuss the investigated radiopurity of TUM-grown crystals in comparison to commercial crystals installed in CRESST. This research was supported by the DFG cluster of excellence: "Origin and Structure of the Universe", the "Helmholtz Alliance for Astroparticle Phyiscs", the "Maier-Leibnitz-Laboratorium" (Garching) and by the BMBF: Project 05A11WOC EURECA-XENON.