Search of the neutrino-less double beta decay of 82 Se into the excited states of 82 Kr with CUPID-0

Abstract

The CUPID-0 experiment searches for double beta decay using cryogenic calorimeters with double (heat and light) read-out. The detector, consisting of 24 ZnSe crystals 95 $\%$ enriched in ${}^{82}$ Se and two natural ZnSe crystals, started data-taking in 2017 at Laboratori Nazionali del Gran Sasso. We present the search for the neutrino-less double beta decay of ${}^{82}$ Se into the 0 ${}_1^{+}$ , 2 ${}_1^{+}$ and 2 ${}_2^{+}$ excited states of ${}^{82}$ Kr with an exposure of 5.74 kg $·$ yr (2.24 $\times$ 10 ${}^{25}$ emitters $·$ yr). We found no evidence of the decays and set the most stringent limits on the widths of these processes: $\Gamma$ ( ${}^{82}$ Se ${\to }^{82}$ Kr ${}_{0_1^{+}}$ )8.55 $\times$ 10 ${}^{-24}$ yr ${}^{-1}$ , $\Gamma$ ( ${}^{82}$ Se ${\to }^{82}$ Kr ${}_{2_1^{+}}$ ) $<6.25\times {10}^{-24}$ yr ${}^{-1}$ , $\Gamma$ ( ${}^{82}$ Se ${\to }^{82}$ Kr ${}_{2_2^{+}}$ )8.25 $\times$ 10 ${}^{-24}$ yr ${}^{-1}$ (90 $\%$ credible interval).