Scintillation properties and radioactive contamination of CaWO4 crystal scintillators

Energy resolution, α / β ratio and the pulse-shape discrimination ability of the CaWO4 crystal scintillators were studied. The radioactive contamination and background of the crystals were measured in the Solotvina Underground Laboratory. Despite a rather high level of radioactive impurities, the background rate of the CaWO4 detector in the energy window of the 48Ca neutrinoless 2 β decay (3.6–5.4 MeV) was reduced to 0.07 counts/(yr keV kg). The indication for α decay of 180W (Phys. Rev. 67 (2003) 014310) was confirmed (the measured half-life is T 1 / 2 = 1 . 0 - 0.3 + 0.7 × 10 18yr).