  We report on the final results of a series of experiments on double decay of
130Te carried out with an array of twenty cryogenic detectors. The set-up is
made with crystals of TeO2 with a total mass of 6.8 kg, the largest operating
one for a cryogenic experiment. Four crystals are made with isotopically
enriched materials: two in 128Te and two others in 130Te. The remaining ones
are made with natural tellurium, which contains 31.7 % and 33.8 % 128Te and
130Te, respectively. The array was run under a heavy shield in the Gran Sasso
Underground Laboratory at a depth of about 3500 m.w.e. By recording the pulses
of each detector in anticoincidence with the others a lower limit of 2.1E23
years has been obtained at the 90 % C.L. on the lifetime for neutrinoless
double beta decay of 130Te. In terms of effective neutrino mass this is the
most restrictive limit in direct experiments, after those obtained with Ge
diodes. Limits on other lepton violating decays of 130Te and on the
neutrinoless double beta decay of 128Te to the ground state of 128Xe are also
reported and discussed. An indication is presented for the two neutrino double
beta decay of 130Te. Some consequences of the present results in the
interpretation of geochemical experiments are discussed.
