A CUPID Li2100MoO4 scintillating bolometer tested in the CROSS underground facility

A scintillating bolometer based on a large cubic (Li2MoO4)-Mo-100 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 nu 2 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 (Li2MoO4)-Mo-100 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 (Li2MoO4)-Mo-100 bolometer allowed for a full separation (similar to 8 sigma) between gamma(beta) and alpha events above 2 MeV. The (Li2MoO4)-Mo-100 crystal also shows a high internal radiopurity with Th-228 and Ra-226 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 (Li2MoO4)-Mo-100 scintillating bolometers for high-sensitivity searches for the Mo-100 0 nu 2 beta decay in CROSS and CUPID projects.

Automated summary

This study conducted experiments on a scintillating bolometer based on (Li2MoO4)-Mo-100 crystal and a Ge wafer at the underground laboratory in Spain, confirming its potential and performance for the CROSS and CUPID projects.