CRYOGENIC THERMAL DETECTORS AS A POWERFUL WAY TO ANALYZE INTERNAL ACTIVITIES

The Milano group is using an array of four crystals of TeO2, 334 g eac h, to search for neutrinoless double beta decay of Te-130 [A. Alessand rello et al., Phys. Lett. B 335 (1994) 519; Proc. 4th Int. Workshop on Theoretical and Phenomenological Aspects of Underground Physics - TAU P 95, to be published in Nucl. Phys. B (Proc. Suppl)]. The detectors a re operating in a dilution refrigerator installed in the Underground N ational Laboratory of Gran Sasso specially built with low activity mat erials. Due to the low external background and the good energy resolut ion it is possible to obtain precise measurements of some internal con taminations of the detector itself. An analysis of a contamination of Po-210 and of the decay of Te-123 is presented.