Compact phonon-scintillation detection system for rare event searches at low temperatures

We have developed a compact cryogenic measurement system to investigate the phonon and scintillation properties of various scintillating crystals. This system employs a 1 x 1 x 1 cm(3) crystal for the simultaneous detection of heat (phonon) and light (scintillation) signals based on metallic magnetic calorimeter (MMC) readouts at milliKelvin temperatures. Three molybdate crystals of CaMoO4, Na2Mo2O7, and Li2MoO4 were tested in the detector system. This work surveys scintillating crystals as target materials for neutrinoless double beta (0 nu beta beta) decay of Mo-100. All the measurements are successful in simultaneously detecting heat and light signals from the crystals. The measurements also results in clear particle identification using the pulse shapes and the relative amplitude ratios of the heat and light signals. We report the performance of the detector system through the amplitudes and time constants of the signals and the particle identification discrimination powers with discussion on 0 nu beta beta applications.