Li2100deplMoO4 Scintillating Bolometers for Rare-Event Search Experiments

We report on the development of scintillating bolometers based on lithium molybdate crystals that contain molybdenum that has depleted into the double- (Formula presented.) active isotope (Formula presented.) Mo (Li (Formula presented.) (Formula presented.) MoO (Formula presented.)). We used two Li (Formula presented.) (Formula presented.) MoO (Formula presented.) cubic samples, each of which consisted of 45-millimeter sides and had a mass of 0.28 kg; these samples were produced following the purification and crystallization protocols developed for double- (Formula presented.) search experiments with (Formula presented.) Mo-enriched Li (Formula presented.) MoO (Formula presented.) crystals. Bolometric Ge detectors were utilized to register the scintillation photons that were emitted by the Li (Formula presented.) (Formula presented.) MoO (Formula presented.) crystal scintillators. The measurements were performed in the CROSS cryogenic set-up at the Canfranc Underground Laboratory (Spain). We observed that the Li (Formula presented.) (Formula presented.) MoO (Formula presented.) scintillating bolometers were characterized by an excellent spectrometric performance (∼3–6 keV of FWHM at 0.24–2.6 MeV (Formula presented.) s), moderate scintillation signal (∼0.3–0.6 keV/MeV scintillation-to-heat energy ratio, depending on the light collection conditions), and high radiopurity ((Formula presented.) Th and (Formula presented.) Ra activities are below a few µBq/kg), which is comparable with the best reported results of low-temperature detectors that are based on Li (Formula presented.) MoO (Formula presented.) using natural or (Formula presented.) Mo-enriched molybdenum content. The prospects of Li (Formula presented.) (Formula presented.) MoO (Formula presented.) bolometers for use in rare-event search experiments are briefly discussed.