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

• Received 21 February 2018
• Revised 16 April 2018

DOI:https://doi.org/10.1103/PhysRevLett.120.232502