Evidence of Single State Dominance in the Two-Neutrino Double- ? Decay of Se 82 with CUPID-0
01 Pubblicazione su rivista
Azzolini O., Beeman J. W., Bellini F., Beretta M., Biassoni M., Brofferio C., Bucci C., Capelli S., Cardani L., Carniti P., Casali N., Chiesa D., Clemenza M., Cremonesi O., Cruciani A., Dafinei I., Di Domizio S., Ferroni F., Gironi L., Giuliani A., Gorla P., Gotti C., Keppel G., Kotila J., Martinez M., Nagorny S., Nastasi M., Nisi S., Nones C., Orlandi D., Pagnanini L., Pallavicini M., Pattavina L., Pavan M., Pessina G., Pettinacci V., Pirro S., Pozzi S., Previtali E., Puiu A., Rusconi C., Schaffner K., Tomei C., Vignati M., Zolotarova A.
ISSN: 0031-9007
We report on the measurement of the two-neutrino double-? decay of Se82 performed for the first time with cryogenic calorimeters, in the framework of the CUPID-0 experiment. With an exposure of 9.95 kg yr of ZnSe82, we determine the two-neutrino double-? decay half-life of Se82 with an unprecedented precision level, T1/22?=[8.60±0.03(stat) -0.13+0.19(syst)]×1019 yr. The very high signal-to-background ratio, along with the detailed reconstruction of the background sources allowed us to identify the single state dominance as the underlying mechanism of such a process, demonstrating that the higher state dominance hypothesis is disfavored at the level of 5.5?.