  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$_{4}$ 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.
