Preliminary results on double beta decay of 130Te with an array of twenty cryogenic detectors

Preliminary results on double beta decay of 130Te obtained in the first run of an array of twenty cryogenic detectors are presented. The set-up is made with crystals of TeO2 of 340 grams each corresponding to the largest presently operating cryogenic mass. It 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 90% c.l. lower limit of 5.6×1022 years has been obtained on the lifetime for neutrinoless double beta decay of 130Te in a preliminary test run, corresponding to about one week of effective running time. No evidence is also found for double beta decay to the first excited 2+ state of 130Xe with a 90% c.l. lower limit of 1.7×1022 years on that lifetime. Some consequences of the present results in the interpretation of geochemical experiments are discussed.