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 T 1 / 2 0 ν > 10 27 yr. This value corresponds to the neutrino mass constraint mν < (0.04–0.09) eV.