Growth and development of pure Li2MoO4 crystals 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 (0 nu beta beta) of Mo-100 in the molybdate crystals of the AMoRE experiment. The experiment requires pure scintillation crystals to minimize internal backgrounds that can affect the 0 nu beta beta 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 (Li2MoO4)-Mo-100 crystal, we have studied (Li2MoO4)-Mo-nat crystal growth by a conventional Czochralski (CZ) grower. We grew a few different kinds of Li(2)(nat)MO(4)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.