Latest results from CUPID-0

Abstract

CUPID-0 is a pilot experiment in scintillating cryogenic calorimetry for the search of neutrino-less double beta decay. 26 ZnSe crystals were operated continuously in the first project phase (March 2017 -December 2018), demonstrating unprecedented low levels of background in the region of interest at the Q-value of 82 Se. From this successful experience comes a demonstration of full alpha to beta/gamma background separation, the most stringent limits on the 82 Se neutrino-less double beta decay, as well as the most precise measurement of the 82 Se half-life. After a detector upgrade, CUPID-0 began its second and last phase (June 2019 -February 2020). We present the latest results on the neutrino-less double beta decay of 82 Se with the full isotope exposure of 8.82 kg × yr. We set a lower bound to the ground state half life T 1/2 ( 82 Se) > 4.6 × 10 24 yr (90% C.I.). We review the most recent results from a Bayesian search for spectral distortions to the 82 Se double-beta decay spectrum due to exotic decay modes.