Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 79: Suche nach Dunkler Materie 3 (Direkter Nachweis)

T 79.3: Talk

Wednesday, March 29, 2017, 17:25–17:40, VSH 19

Production of high-purity CaWO₄ crystals for direct dark matter search with CRESST — •Andrea Münster for the CRESST collaboration — Physik-Department and Excellence Cluster Universe, Technische Universität München, D-85748 Garching

The direct dark matter search experiment CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) uses scintillating CaWO₄ single crystals as targets to search for possible recoils of dark matter particles. Since several years these CaWO₄ crystals have been produced directly at the Technische Universität München (TUM) including the CaWO₄ powder production from the raw materials CaCO₃ and WO₃, the CaWO₄ crystal growth via the Czochralski method as well as the after-growth treatment of the crystals. In CRESST-II Phase 2 (2013-2015), 4 TUM-grown crystals were operated in the experiment for the first time, showing the best radiopurities of all crystals installed. Therefore, in CRESST-III Phase 1 (started in summer 2016) mainly TUM-grown crystals have been included. The goal for the upcoming CRESST-III Phase 2 is a further improvement of the radiopurity. A method to chemically purify the raw materials was developed at TUM and will be presented together with first promising results. This research was supported by the DFG cluster of excellence "Origin and Structure of the Universe", by the Helmholtz Alliance for Astroparticle Physics, by the Maier-Leibnitz-Laboratorium (Garching) and by the BMBF.