PbMoO4 Synthesis from Ancient Lead and Its Single Crystal Growth for Neutrinoless Double Beta Decay Search

Arshad Khan,Moo Hyun Lee,Pabitra Aryal,Hongjoo Kim,Yeongduk Kim

doi:10.3390/cryst10030150

Abstract

A powder synthesis of PbMoO4 (PMO) 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 the Czochralski technique in an Ar environment. The luminescence and scintillation properties were measured with excitations using UV, X- and γ-rays in the temperature range of 10–300 K. Annealing of the grown PMO crystal in an air atmosphere significantly enhanced the scintillation light yield compared to that measured before annealing. The scintillation light yield of grown PMO crystal at 10 K was 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 a lower internal activity from 210Pb compared to that of reference PMO (grown from modern Pb) crystal. These preliminary performances show that the PMO crystal grown from ancient Pb and deeply purified MoO3 powders has a great potential to be used as a cryogenic scintillator for the neutrinoless double beta decay search in 100Mo.

Highlights

PbMoO4 (PMO) is one of the most extensively studied materials because of its wider applications in acousto-optics [1], optoelectronics [2], photocatalysis [3], and high voltage measuring devices
The intrinsic background imposed by 210 Pb in the PMO crystal grown from commercial precursors limits its applications in rare event search experiments [20]. This intrinsic background can be reduced by utilizing the ancient Pb for the powder synthesis and PMO crystal growth
This study focuses on the powder synthesis of PMO directly from an ancient Pb and commercial and deeply purified MoO3 powders by a wet chemistry technique for the first time

Summary

Introduction

PbMoO4 (PMO) is one of the most extensively studied materials because of its wider applications in acousto-optics [1], optoelectronics [2], photocatalysis [3], and high voltage measuring devices. Single crystals belonging to the scheelite structure have been widely studied due to their common luminescence features for the applications in high energy physics, dark matter, and double beta decay searches [15,16,17,18,19,20]. The intrinsic background imposed by 210 Pb in the PMO crystal grown from commercial precursors limits its applications in rare event search experiments [20] This intrinsic background can be reduced by utilizing the ancient Pb for the powder synthesis and PMO crystal growth. The scintillation performance of the PMO crystal grown from powders synthesized from ancient Pb and deeply purified MoO3 powders was studied under γ-ray excitation in the temperature range of 10–300 K and compared with a reference PMO crystal. Stimulated luminescence (TSL) measured after x-ray irradiation at 10 K shows multiple traps, which causes quenching of light yield at low temperatures due to the self-trapping of electrons at (MoO4 )2− complexes

Powders Synthesis

Crystal Growth

Characterizations

Results

Conclusions

Methods