$^{100}$Mo-enriched Li$_2$MoO$_4$ scintillating bolometers for $0\nu 2\beta$ decay search: From LUMINEU to CUPID-0/Mo projects
Résumé
A scintillating bolometer technology based on 100Mo-enriched lithium molybdate (Li2100MoO4) crystals has been developed by LUMINEU to search for neutrinoless double-beta (0ν2β) decay of 100Mo. The results of several low temperature tests at underground environments have proved the reproducibility of high detector performance and crystal radiopurity: in particular ∼5–6 keV FWHM energy resolution and at least 9σ rejection of α’s in the vicinity of the 0ν2β decay of 100Mo (3034 keV) and below 10 µBq/kg bulk activity of 228Th and 226Ra. A modest acquired exposure (0.1 kg×yr) is a limiting factor of the LUMINEU experiment sensitivity to the 0ν2β decay half-life of 100Mo (T1/2 ≥ 0.7×1023 yr at 90% C.L.), however the two-neutrino 2β decay has been measured with the best up to-date accuracy, T1/2 = [6.92 ± 0.06(stat.) ± 0.36(syst.)l × 1018 yr. The applicability of the LUMINEU technology for a tonne-scale 0ν2β decay bolometric project CUPID is going to be demonstrated by the CUPID-0/Mo experiment with ∼5 kg of 100Mo embedded in forty 0.2 kg Li2100MoO4 scintillating bolometers. A first phase of the experiment with twenty Li2100MoO4 detectors is in preparation at the Modane underground laboratory (France) to start by the end of 2017.