The background model of the CUPID-Mo 0νββ experiment

CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation 0 nu beta beta decay experiment, CUPID. It consisted of an array of 20 enriched Li-2 (MoO4)-Mo-100 bolometers and 20 Ge light detectors and has demonstrated that the technology of scintillating bolometers with particle identification capabilities is mature. Furthermore, CUPID-Mo can inform and validate the background prediction for CUPID. In this paper, we present a detailed model of the CUPID-Mo backgrounds. This model is able to describe well the features of the experimental data and enables studies of the 2 nu beta beta decay and other processes with high precision. We also mea sure the radio-purity of the Li-2 (MoO4)-Mo-100 crystals which are found to be sufficient for the CUPID goals. Finally, we also obtain a background index in the region of interest of 3.7 (+0.9)(-0.8) (stat)(-0.7)(+1.5) (syst) x10(-3) counts/ Delta E-FWHM/moliso/year, the lowest in a bolometric 0 nu beta beta decay experiment.

Automated summary

CUPID-Mo, a demonstrator for the next generation 0 nu beta beta decay experiment CUPID, has matured the technology of scintillating bolometers with particle identification capabilities. In this paper, a detailed model of CUPID-Mo backgrounds is presented, allowing for high precision studies of beta beta decay and other processes. The radio-purity of the Li-2(MoO4)-Mo-100 crystals is measured and found to be sufficient for CUPID's goals.