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

The use of cryogenic thermal particle detectors permits the realization of detectors of various compositions, various sizes and very good energy resolution. In particular these characteristics are very promising for the realization of double beta decay and dark matter search experiments. Our group is mainly interested in the study of double beta decay of Te-130 and Cd-116. For tellurium we have realized various detectors using TeO2 crystals, the final one with a mass of 334 g. For cadmium a CdWO4 crystal of 58 g has been used in various tests. The double beta decay measurement has been performed in the Gran Sasso Underground Laboratory. Measurements on the 334 g TeO2 Crystal have been performed for 3000 h. Detector resolution is around 10 keV FWHM and the internal 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 test 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 neutrinoless 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-life of (9.3 +/- 0.5 +/- 1) x 10(15) yr for the beta decay of Cd-113 are also measured. The last part of the paper is dedicated to a brief discussion of our proposal for the solar neutrino flux measurement and for the search of dark matter using cryogenic detectors.