Li₂^100deplMoO₄ Scintillating Bolometers for Rare-Event Search Experiments.

Area of Science:

• Experimental physics
• Low-temperature detectors
• Nuclear astrophysics

Background:

• Scintillating bolometers are crucial for rare-event searches.
• Lithium molybdate crystals enriched with molybdenum-100 have been used in previous experiments.
• Development of detectors with depleted molybdenum-100 is essential for background reduction.

Purpose of the Study:

• To develop and characterize scintillating bolometers using lithium molybdate crystals with depleted molybdenum-100 (Li2100deplMoO4).
• To evaluate the performance of these detectors in terms of energy resolution, scintillation signal, and radiopurity.
• To assess their potential for future rare-event search experiments.

Main Methods:

• Synthesis and purification of Li2100deplMoO4 crystals.
• Fabrication of cubic bolometer samples (45 mm sides, 0.28 kg mass).
• Detection of scintillation photons using bolometric Ge detectors in a cryogenic setup (CROSS at Canfranc Underground Laboratory).

Main Results:

• Li2100deplMoO4 scintillating bolometers demonstrated excellent spectrometric performance (3-6 keV FWHM at 0.24-2.6 MeV).
• A moderate scintillation-to-heat energy ratio (0.3-0.6 keV/MeV) was observed.
• High radiopurity was achieved, with 228Th and 226Ra activities below a few µBq/kg.

Conclusions:

• The developed Li2100deplMoO4 scintillating bolometers exhibit performance comparable to state-of-the-art low-temperature detectors.
• Their excellent characteristics and high radiopurity make them highly suitable for rare-event search experiments.
• These findings pave the way for enhanced sensitivity in future searches for rare nuclear processes.