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Title: Radiopurity of CaWO{sub 4} crystals for direct dark matter search with CRESST and EURECA

The direct dark matter search experiment CRESST uses scintillating CaWO{sub 4} single crystals as targets for possible WIMP scatterings. An intrinsic radioactive contamination of the crystals as low as possible is crucial for the sensitivity of the detectors. In the past CaWO{sub 4} crystals operated in CRESST were produced by institutes in Russia and the Ukraine. Since 2011 CaWO{sub 4} crystals have also been grown at the crystal laboratory of the Technische Universität München (TUM) to better meet the requirements of CRESST and of the future tonne-scale multi-material experiment EURECA. The radiopurity of the raw materials and of first TUM-grown crystals was measured by ultra-low background γ-spectrometry. Two TUM-grown crystals were also operated as low-temperature detectors at a test setup in the Gran Sasso underground laboratory. These measurements were used to determine the crystals' intrinsic α-activities which were compared to those of crystals produced at other institutes. The total α-activities of TUM-grown crystals as low as 1.23±0.06 mBq/kg were found to be significantly smaller than the activities of crystals grown at other institutes typically ranging between ∼ 15 mBq/kg and ∼ 35 mBq/kg.
Authors:
; ; ; ; ; ;  [1] ; ; ; ; ;  [2] ; ; ; ;  [3] ; ;  [4] ;  [5] ;  [6] more »; « less
  1. Physik-Department, Technische Universität München, D-85748 Garching (Germany)
  2. Max-Planck-Institut für Physik, D-80805 München (Germany)
  3. INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi (Italy)
  4. Physikalisches Institut, Eberhard-Karls-Universität Tübingen, D-72076 Tübingen (Germany)
  5. Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom)
  6. Grupo de Física Nuclear y Astropartículas, Universidad de Zaragoza, ES-50009 Zaragoza (Spain)
Publication Date:
OSTI Identifier:
22373578
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 05; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CALCIUM TUNGSTATES; COMPARATIVE EVALUATIONS; CONTAMINATION; GAMMA SPECTROSCOPY; MONOCRYSTALS; NONLUMINOUS MATTER; RAW MATERIALS; RUSSIAN FEDERATION; SENSITIVITY; UKRAINE; UNDERGROUND