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 2β 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 T1/2=1.0-0.3+0.7×10 18yr).