CARVEL experiment with 48CaWO4 crystal scintillators for the double β decay study of 48Ca

The CARVEL (CAlcium Research for VEry Low neutrino mass) experiment to search for the double β decay of 48Ca with the help of enriched 48CaWO4 crystal scintillators has been considered. Scintillation properties (energy resolution, α/β ratio, pulse-shape discrimination ability) and radiopurity of CaWO4 scintillators were studied. Despite rather high radioactive contaminations, the background rate of the CaWO4 detector in the energy region 3.6-5.4 MeV (energy window of the 48Ca neutrinoless 2β decay) was reduced down to 0.07 counts/(yr keV kg). With ≈100 kg array of the 48CaWO4 crystals the sensitivity of the CARVEL experiment (in terms of the half-life limit for the 0ν2β decay) is estimated as T1/20ν>1027 yr. This value corresponds to the neutrino mass constraint mν < (0.04-0.09) eV.