A CUPID Li2100MoO4scintillating bolometer tested in the CROSS underground facility

Author(s): Armatol, A; Armengaud, E; Armstrong, W; Augier, C; III, Avignone FT; Azzolini, O; Bandac, IC; Barabash, AS; Bari, G; Barresi, A; Baudin, D; Bellini, F; Benato, G; Beretta, M; Berge, L; Bourgeois, Ch; Biassoni, M; Billard, J; Boldrini, V; Branca, A; Brofferio, C; Bucci, C; Calvo-Mozota, JM; Camilleri, J; Candela, A; Capelli, S; Cappelli, L; Cardani, L; Carniti, P; Casali, N; Cazes, A; Celi, E; Chang, C; Chapellier, M; Charrier, A; Chiesa, D; Clemenza, M; Colantoni, I; Collamati, F; Copello, S; Cremonesi, O; Creswick, RJ; Cruciani, A; D'Addabbo, A; D'Imperio, G; Dafinei, I; Danevich, FA; de Combarieu, M; De Deo, M; De Jesus, M; de Marcillac, P; Dell'Oro, S; Di Domizio, S; Dompe, V; Drobizhev, A; Dumoulin, L; Fantini, G; Faverzani, M; Ferri, E; Ferri, F; Ferroni, F; Figueroa-Feliciano, E; Formaggio, J; Franceschi, A; Fu, C; Fu, S; Fujikawa, BK; Gascon, J; Giachero, A; Gironi, L; Giuliani, A; Gorla, P; Gotti, C; Gras, P; Gros, M; Guerard, E; Gutierrez, TD; Han, K; Hansen, EV; Heeger, KM; Helis, DL; Huang, HZ; Huang, RG; Ianni, A; Imbert, L | Abstract: A scintillating bolometer based on a large cubic Li$_{2}$$^{100}$MoO$_4$ crystal (45 mm side) and a Ge wafer (scintillation detector) has been operated in the CROSS cryogenic facility at the Canfranc underground laboratory in Spain. The dual-readout detector is a prototype of the technology that will be used in the next-generation $0\nu2\beta$ experiment CUPID. The measurements were performed at 18 and 12 mK temperature in a pulse tube dilution refrigerator. This setup utilizes the same technology as the CUORE cryostat that will host CUPID and so represents an accurate estimation of the expected performance. The Li$_{2}$$^{100}$MoO$_4$ bolometer shows a high energy resolution of 6 keV FWHM at the 2615 keV $\gamma$ line. The detection of scintillation light for each event triggered by the Li$_{2}$$^{100}$MoO$_4$ bolometer allowed for a full separation ($\sim$8$\sigma$) between $\gamma$($\beta$) and $\alpha$ events above 2 MeV. The Li$_{2}$$^{100}$MoO$_4$ crystal also shows a high internal radiopurity with $^{228}$Th and $^{226}$Ra activities of less than 3 and 8 $\mu$Bq/kg, respectively. Taking also into account the advantage of a more compact and massive detector array, which can be made of cubic-shaped crystals (compared to the cylindrical ones), this test demonstrates the great potential of cubic Li$_{2}$$^{100}$MoO$_4$ scintillating bolometers for high-sensitivity searches for the $^{100}$Mo $0\nu2\beta$ decay in CROSS and CUPID projects.