Thermal Model and Optimization of a Large Crystal Detector Using a Metallic Magnetic Calorimeter

We established a simple thermal model of the heat flow in a large crystal detector designed for a neutrinoless double beta decay experiment. The detector is composed of a CaMoO$$_{4}$$4 crystal and a metallic magnetic calorimeter (MMC). The thermal connection between the absorber and the sensor consists of a gold film evaporated on the crystal surface and gold bonding wires attached to this film and the MMC sensor. The model describes athermal and thermal processes of heat flow to the gold film. A successive experiment based on optimization calculations of the area and thickness of the gold film showed a significant improvement in the size and rise-time of the measured signals.