The background model of the CUPID-Mo $$0\nu \beta \beta $$ experiment
C. Augier, A. S. Barabash, F. Bellini, G Benato, M. Beretta, L. Bergé, J. Billard, Yu. A. Borovlev, L. Cardani, N. Casali, Aurélie Cazes, E. Celi, M. Chapellier, D. Chiesa, I. Dafinei, F.A. Danevich, M de Jesus, P de Marcillac, T. Dixon, L. Dumoulin, K. Eitel, F. Ferri, B. K. Fujikawa, J. Gascon, L. Gironi, A. Giuliani, V. D. Grigorieva, M. Gros, D. Helis, H. Z. Huang, Roger Huang, L. Imbert, J. Johnston, A. Juillard, H. Khalife, M. Kleifges, V. Kobychev, Yu. G. Kolomensky, С. И. Коновалов, J. Kotila, P. Loaiza, L. Ma, E. P. Makarov, R. Mariam, L. Marini, S. Marnieros, X.-F. Navick, C. Nones, E. B. Norman, E. Olivieri, J.L Ouellet, L. Pagnanini, L. Pattavina, B. Paul, M. Pavan, H. Peng, G. Pessina, S. Pirro, D.V Poda, O. G. Polischuk, S. Pozzi, E. Previtali, T. Redon, A. Rojas, S. Rozov, V. Sanglard, J. A. Scarpaci, B. Schmidt, Yandi Shen, V. N. Shlegel, V. Singh, C. Tomei, V.I. Tretyak, V. I. Umatov, L. Vagneron, M. Velázquez, B. Welliver, L. A. Winslow, M. Xue, E. Yakushev, M.M Zarytskyy, A. Zolotarova
Abstract
Abstract CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation $$0\nu \beta \beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0</mml:mn> <mml:mi>ν</mml:mi> <mml:mi>β</mml:mi> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> decay experiment, CUPID. It consisted of an array of 20 enriched Li $$_{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow/> <mml:mn>2</mml:mn> </mml:msub> </mml:math> $$^{100}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>100</mml:mn> </mml:msup> </mml:math> MoO $$_4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow/> <mml:mn>4</mml:mn> </mml:msub> </mml:math> 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 $$2\nu \beta \beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>2</mml:mn> <mml:mi>ν</mml:mi> <mml:mi>β</mml:mi> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> decay and other processes with high precision. We also measure the radio-purity of the Li $$_{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow/> <mml:mn>2</mml:mn> </mml:msub> </mml:math> $$^{100}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow/> <mml:mn>100</mml:mn> </mml:msup> </mml:math> MoO $$_4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow/> <mml:mn>4</mml:mn> </mml:msub> </mml:math> 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 $$^{+0.9}_{-0.8}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>0.8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.9</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> (stat) $$^{+1.5}_{-0.7}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>0.7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.5</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> (syst) $$\times ~10 ^{-3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>×</mml:mo> <mml:mspace/> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> counts/ $$\Delta E_{\text {FWHM}}/\text {mol}_{\text {iso}}/\text {year},$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>E</mml:mi> <mml:mtext>FWHM</mml:mtext> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mtext>mol</mml:mtext> <mml:mtext>iso</mml:mtext> </mml:msub> <mml:mo>/</mml:mo> <mml:mtext>year</mml:mtext> <mml:mo>,</mml:mo> </mml:mrow> </mml:math> the lowest in a bolometric $$0\nu \beta \beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0</mml:mn> <mml:mi>ν</mml:mi> <mml:mi>β</mml:mi> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> decay experiment.