PbMoO<sub>4 </sub>Synthesis from Ancient Lead and Its Single Crystal Growth for Neutrinoless Double Beta Decay Search

A powder synthesis of PbMoO4 from ancient lead (Pb) and deeply purified commercial MoO3 powders was performed using a wet chemistry technique to achieve the low radioactivity scintillator for neutrinoless double beta decay search in 100Mo. The synthesized powders were used to grow single crystals of PbMoO4 by a Czochralski technique in Ar environment. The luminescence and scintillation properties were measured with excitations using UV, X- and γ-rays in temperature range of 10-300 K. Annealing of the grown PMO crystal in air atmosphere enhanced the scintillation light yield by ~3 orders of magnitude compared to that measured before annealing. The scintillation light yield of grown PMO crystal at 10 K is found to be 127% to that of a reference PMO crystal under 662 keV γ-rays excitation from a 137Cs source. The background measurement of the grown crystal performed at 50 K shows negligible activity from 210Pb compared to that of reference PMO crystal. These preliminary performances show that the PMO crystal grown from ancient Pb and deeply purified MoO3 powders has the great potential to be used as cryogenic scintillator for the neutrinoless double beta decay search in 100Mo.