Scintillating Bolometers for Double Beta Decay Search

In the field of Double Beta Decay searches the possibility to have high resolution detectors in which a very large part of the natural background can be discriminated with respect to the tiny expected signal, results very appealing. This very interesting possibility can be fulfilled in the case of a scintillating crystal bolometer containing a DBD emitter whose transition energy exceeds the one of the natural 2615 keV gamma line of ²⁰⁸Tl. We present the results achieved in the development of bolometric light detectors for double beta searches. The detectors are 1 mm thick germanium disk coated with a layer of SiO₂ in order to increase the light collection. The adopted temperature sensors are NTD Ge thermistors optimized to work at temperatures between 9 and 13 mK. A light detector with a considerable large area (35 cm²) was constructed and run in a test measurement. A 140 g CdWO₄ crystal (¹¹⁶Cd has a DBD transition energy of 2802 keV) was operated as bolometer and the scintillation light was read by the light detector. The excellent results combined with extreme easy light detector assembly represent the first tangible proof demonstrating the feasibility of this kind of technique.