$$\hbox {Li}_2\hbox {MoO}_4$$ Phonon–Scintillation Detection Systems with MMC Readout

Abstract

We developed measurement systems for the simultaneous detection of phonon and scintillation signals from $$\hbox {Li}_2\hbox {MoO}_4$$ crystals based on the metallic magnetic calorimeter (MMC) technology. Two measurements were carried out using $$\hbox {Li}_2\hbox {MoO}_4$$ crystals of different sizes. The first measurement was conducted with a compact detection system designed for a $$1\times 1\times 1~\hbox {cm}^3$$ crystal. An advanced light detector with Neganov–Luke phonon amplification was adopted in the compact setup. Later, the second experiment was carried out using a cylindrical $$\hbox {Li}_2\hbox {MoO}_4$$ crystal of 5 cm in diameter and 5 cm in height. Another light detector was implemented with a 2-in. Ge wafer and an MMC sensor. Both measurements resulted in simultaneous detection of heat and light signals. Clear particle discriminations between $$\alpha $$- and $$\beta /\gamma $$-induced events were demonstrated by comparing amplitudes of the heat and light signals in both measurements. The heat signals in the larger setup showed an energy resolution of 18 keV FWHM for 2615 keV $$\gamma $$-rays. The energy linearity of the detector response was investigated for a suitable calibration near 3.034 MeV, the Q value of $$^{100}\hbox {Mo}$$ double-beta decay.