LARGE CALORIMETRIC DEVICES FOR DOUBLE BETA-DECAY AND DARK-MATTER

The use of cryogenic thermal particle detectors permits the realizatio n of detectors of various compositions, various sizes and very good en ergy resolution. In particular these characteristics are very promisin g for the realization of double beta decay and dark matter search expe riments. Our group is mainly interested in the study of double beta de cay of Te-130 and Cd-116. For tellurium we have realized various detec tors using TeO2 crystals, the final one with a mass of 334 g. For cadm ium a CdWO4 crystal of 58 g has been used in various tests. The double beta decay measurement has been performed in the Gran Sasso Undergrou nd Laboratory. Measurements on the 334 g TeO2 Crystal have been perfor med for 3000 h. Detector resolution is around 10 keV FWHM and the inte rnal contamination of U-238 and Th-232 in the crystal is of the order of 10(-13) g/g. A lower limit on the half-life of neutrinoless double beta decay for Te-130 of 8.2 x 10(21) yr (90% CL) is measured. The tes t measurements of CdWO4 reach an energy resolution of about 5 keV FWHM with a very high efficiency to gamma ray detection. A limit on the ne utrinoless channel of 7 x 10(19) yr (90% CL) is evaluated in 340 h. In this test an end point energy of 318.8 +/- 1.4 +/- 5 keV and a half-l ife of (9.3 +/- 0.5 +/- 1) x 10(15) yr for the beta decay of Cd-113 ar e also measured. The last part of the paper is dedicated to a brief di scussion of our proposal for the solar neutrino flux measurement and f or the search of dark matter using cryogenic detectors.