Growth of high-purity scintillating CaWO4 single crystals for the low-temperature direct dark matter search experiments CRESST-II and EURECA

Direct dark matter detection is one of the approaches from which astroparticle physicists would like to learn about the nature of this unknown form of matter which constitutes about 23% of the Universe's mass content. CRESST and the planned EURECA experiment are Dark Matter searches which employ low-temperature detectors to measure interactions of Dark Matter with ordinary matter directly. CRESST uses scintillating CaWO 4 single crystals as a target for Dark Matter particles. It is planned to increase the number of detectors drastically in the near future. To achieve the production of this next generation of detectors an inhouse production of CaWO 4 crystals was set up to ensure the availability of ultra-pure crystals with optimized light yield and ultra-low radioactive background. In the CRESST experiment scintillating CaWO 4 single crystals are used as a target material for dark matter particles. The article describes the production of ultra-pure crystals of CaWO 4 crystals.