Development of100Mo -containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search

This paper reports on the development of a tech- nology involving 100 Mo-enriched scintillating bolometers, compatible with the goals of CUPID, a proposed next- generation bolometric experiment to search for neutrinoless double-beta decay. Large mass (∼ 1 kg), high optical qual- ity, radiopure 100Mo-containing zinc and lithium molybdate crystals have been produced and used to develop high perfor- mance single detector modules based on 0.2–0.4 kg scintil- lating bolometers. In particular, the energy resolution of the lithium molybdate detectors near the Q-value of the double- beta transition of 100Mo (3034 keV) is 4–6 keV FWHM. The rejection of the α-induced dominant background above 2.6 MeV is better than 8σ . Less than 10 μBq/kg activity of 232 Th (228 Th) and 226 Ra in the crystals is ensured by boule recrystallization. The potential of 100 Mo-enriched scintillat- ing bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only 10 kg×d exposure: the two neutrino double-beta decay half-life of 100Mo has been measured with the up-to-date highest accuracy as T1/2 = [6.90 ± 0.15(stat.) ± 0.37(syst.)] × 1018 years. Both crystal- lization and detector technologies favor lithium molybdate, which has been selected for the ongoing construction of the CUPID-0/Mo demonstrator, containing several kg of 100Mo.