First Result on the Neutrinoless Double Beta Decay of $^{82}$Se with CUPID-0

TL;DR

This paper reports the first search for neutrinoless double beta decay of $^{82}$Se using CUPID-0, setting new lower limits on the decay half-life and demonstrating advanced background suppression techniques.

Contribution

It introduces CUPID-0's large array of scintillating cryogenic calorimeters with particle identification, achieving unprecedented background suppression for this decay search.

Findings

No signal observed in 1.83 kg yr exposure

Set lower limit on half-life > 2.4×10^{24} yr

Background suppression to (3.6^{+1.9}_{-1.4})×10^{-3} ckky

Abstract

We report the result of the search for neutrinoless double beta decay of $^{82}$Se obtained with CUPID-0, the first large array of scintillating Zn$^{82}$Se cryogenic calorimeters implementing particle identification. We observe no signal in a 1.83 kg yr $^{82}$Se exposure and we set the most stringent lower limit on the \onu $^{82}$Se half-life T$^{0\nu}_{1/2}>$ 2.4$\times \mathrm{10}^{24}$ yr (90\% credible interval), which corresponds to an effective Majorana neutrino mass m$_{\beta\beta} <$ (376-770) meV depending on the nuclear matrix element calculations. The heat-light readout provides a powerful tool for the rejection of \al\ particles and allows to suppress the background in the region of interest down to (3.6$^{+1.9}_{-1.4}$)$\times$10$^{-3}$\ckky, an unprecedented level for this technique.