Growth and development of pure Li₂MoO₄crystals for rare event experiment at CUP

Abstract

The Center for Underground Physics (CUP) of the Institute for Basic Science (IBS) is searching for the neutrinoless double-beta decay (0νββ) of 100 Mo in the molybdate crystals of the AMoRE experiment. The experiment requires pure scintillation crystals to minimize internal backgrounds that can affect the 0νββ signal. For the last few years, we have been growing and studying Li2MoO4 crystals in a clean-environment facility to minimize external contamination during the crystal growth. Before growing Li2 100 MoO4 crystal, we have studied Li2 nat MoO4 crystal growth by a conventional Czochralski (CZ) grower. We grew a few different kinds of Li2 nat MO4 crystals using different raw materials in a campaign to minimize impurities. We prepared the fused Al2O3 refractories for the growth of ingots. Purities of the grown crystals were measured with high purity germanium detectors and by inductively coupled plasma mass spectrometry. The results show that the Li2MoO4 crystal has purity levels suitable for rare-event experiments. In this study, we present the growth of Li2MoO4 crystals at CUP and their purities.

Scintillation in Low-Temperature Particle Detectors

“…The results achieved with the advanced Li 2 MoO 4 cryogenic scintillator [311] triggered an extensive R&D on Li 2 MoO 4 scintillating bolometers recently realized within the ISOTTA and LUMINEU projects [74,345,[475][476][477]. Currently, several R&D activities on the Li 2 MoO 4 development for scintillating bolometers are ongoing world-wide: in France (CLYMENE project [478][479][480][481]), in the Republic of Korea [482][483][484][485], in China [486,487], in the United States [488,489], in Ukraine [490], in addition to the existing crystal growth technologies in Russia [74,311,473,476,[491][492][493][494]. Most of these activities were and are considered part of R&D programs towards large-scale bolometric DBD search experiments CUPID [82,495,496] and AMoRE [81,483].…”

“…b Estimated for α+t events (4.8 MeV sum energy), products of neutron capture by 6 Finally, Li 2 100 MoO 4 scintillators have been selected from the list of 82 Se-, 100 Mo-, 116 Cd-and 130 Te-containing crystals for the realization of the CUPID tonne-scale bolometric experiment [82,283]. Last but not least, Li 2 MoO 4 detector material is also a part of the AMoRE DBD project [81,[483][484][485]. Several Li 2 100 MoO 4 scintillating bolometers (few out of 18 detectors) are operating in the AMoRE-I DBD experiment [465], aiming at investigating the possibility to use Li 2 MoO 4 (instead of CaMoO 4 , see Section 3.2.1) in the large-scale AMoRE-II detector array [81].…”

Preparation of low-radioactive high-purity enriched 100MoO3 powder for AMoRE-II experiment

“…The conventional Czochralski [25] and low-temperature gradient Czochralski (LTG-Cz) [26] methods are used in growing the single bulk crystals for the AMoRE. Molybdenum trioxide 100 MoO 3 enriched with 100 Mo isotope and metals' (Ca, Li, etc.)…”

Development of Cryogenic Detectors for Neutrinoless Double Beta Decay Searches with CUORE and CUPID

“…Moreover, the rejection of the α-induced dominant background above 2.6 MeV is better than 8σ [81,82]. An extensive R&D has been carried out to select the best candidate crystal for a next-generation experiment in the framework of the LUMINEU project and by the AMoRE collaboration [8], converging on Li 2 MoO 4 as best candidate [83,84]. The most advanced example of this technology is the CUPID-Mo experiment.…”