The background model of the CUPID-Mo $$0\nu \beta \beta $$ 0 ν β β experiment

Abstract

Abstract CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation

$$0\nu \beta \beta $$

0 ν β β

decay experiment, CUPID. It consisted of an array of 20 enriched Li

$$_{2}$$

2

$$^{100}$$

100

MoO

$$_4$$

4

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

$$2\nu \beta \beta $$

2 ν β β

decay and other processes with high precision. We also measure the radio-purity of the Li

$$_{2}$$

2

$$^{100}$$

100

MoO

$$_4$$

4

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

$$^{+0.9}_{-0.8}$$

- 0.8

+ 0.9

(stat)

$$^{+1.5}_{-0.7}$$

- 0.7

+ 1.5

(syst)

$$\times ~10 ^{-3}$$

×

10

- 3

counts/

$$\Delta E_{\text {FWHM}}/\text {mol}_{\text {iso}}/\text {year},$$

Δ

E FWHM

/

mol iso

/ year ,

the lowest in a bolometric

$$0\nu \beta \beta $$

0 ν β β

decay experiment.