A Study on PbMoO4 Phonon-Scintillation Detection with MMC Readouts for a Neutrinoless Double Beta Decay Search

Abstract

The advanced Mo-based rare process experiment (AMoRE) is an international project searching for the neutrinoless double beta (0 nu beta beta) decay of Mo-100 using low-temperature calorimetric detection of heat and light signals based on magnetic microcalorimeter (MMC) readouts. Li2MoO4 crystals have been considered as the main target crystals for the second phase of the AMoRE project, which aims to use 100 kg of Mo-100. However, the hygroscopicity of Li2MoO4 requires moistureless processes during surface treatment, storage, detector assembly, and installation. Li2MoO4 crystals are nonhygroscopic and exhibit high scintillation efficiency, often leading to high particle discrimination power in the phonon channel via pulse-shape analysis and light/heat ratio variation. A low-temperature detector setup with a 1 cm 3 cubic crystal of Li2MoO4 was prepared for simultaneous heat and light detection based on MMC readouts. After study of internal background control using archeological Pb, Li2MoO4 crystal can be a promising candidate crystal. We present a feasibility study of Li2MoO4 crystals for a 0 nu beta beta experiment.