Speaker
Description
The CRESST-III (Cryogenic Rare Event Search with Superconducting Thermometers) experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei in a scintillating CaWO4 target crystal. The CaWO4 crystal is operated together with a light detector at O(mK) temperature and read out by a tungsten Transition-Edge-Sensor. For many years these CaWO4 target crystals have successfully been produced in-house at the Technical University of Munich with a focus on a low level of radioactive impurities in the crystals. This is crucial to reduce backgrounds in the region of interest originating from radioactive decays. In order to further improve the CaWO4 crystals, an extensive chemical purification of the raw materials and the synthesized CaWO4 powder has been performed. In addition, a temperature gradient simulation of the growth process and subsequently an optimization of the growth furnace with the goal to reduce the intrinsic stress was carried out.
The crystal TUM93 was grown from this purified powder in the optimized furnace. The poster will present results from the detector module TUM93A which is currently being operated in the ongoing CRESST run.