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

Abstract

The CUPID0 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 2 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$\cdot$yr (2.24$\times$10${}^{25}$ emitters$\cdot$yr). We found no evidence of the decays and set the most stringent limits on the widths of these processes: $\hat{I}“$(${}^{82}$Se ${\to }^{82}$Kr${}_{0_1^{+}}$)$<$8.55$\times$10${}^{-24}$ yr${}^{-1}$, $\hat{I}“$(${}^{82}$Se ${\to }^{82}$Kr${}_{2_1^{+}}$)$<6.25\times 10^{-24}$ yr${}^{-1}$, $\hat{I}“$(${}^{82}$Se ${\to }^{82}$Kr${}_{2_2^{+}}$)$<$8.25$\times$10${}^{-24}$ yr${}^{-1}$ (90$\%$ credible interval