First Result on the Neutrinoless Double- β Decay of Se82 with CUPID-0

Abstract

We report the result of the search for neutrinoless double beta decay of ⁸²Se obtained with CUPID-0, the first large array of scintillating Zn⁸²Se cryogenic calorimeters implementing particle identification. We observe no signal in a 1.83 kg yr⁸²Se exposure, and we set the most stringent lower limit on the 0νββ ⁸²Se half-life T[subscript 1/2][superscript 0ν]>2.4×10²⁴ yr (90% credible interval), which corresponds to an effective Majorana neutrino mass m[subscript ββ] < (376–770) meV depending on the nuclear matrix element calculations. The heat-light readout provides a powerful tool for the rejection of α particles and allows us to suppress the background in the region of interest down to (3.6[subscript -1.4][superscript +1.9])×10⁻³ counts/(keV kg yr), an unprecedented level for this technique.