A NEW SEARCH FOR NEUTRINOLESS BETA-BETA-DECAY WITH A THERMAL DETECTOR

A 334 g TeO2 crystal has been operated at a temperature of around 10 m K for more than one year in a low intrinsic radioactivity dilution ref rigerator installed in the Gran Sasso Underground Laboratory. From the spectrum collected in 9234 h of effective running time we improve our limit on neutrinoless double beta decay of Te-130 by an order of magn itude with respect to our previous experiment. It is the most stringen t on this nucleus and excludes a large contribution of the neutrinoles s mode to the rate of double beta decay found in geochemical experimen ts. Upper limits on the effective neutrino mass and on the contributio ns of right handed currents are given.