MILANO EXPERIMENT ON O-V BETA-BETA-DECAY OF TE-130 WITH A THERMAL DETECTOR

A 73.1 g TeO2 bolometric detector has been operating for more than 4 m onths at about 16 mK in the Gran Sasso Underground Laboratory. Its ene rgy resolution is comparable with that of a Ge diode. We performed two measurements: without (1389 hours of effective running time) and with (1046 hours) an inner ultra-low activity lead shield of about 3.5 cm in every direction. The energy spectra of thermal pulses show no evide nce for 0-nu betabeta decay of Te-130. The corresponding 90% c.l. lowe r limit on the half-life time, 2.7x10(21) y, exceeds the value, quoted by geochemical measurements, for the inclusive (2-nu plus 0-nu decay channels) half-life time: 8x10(20)y[1]. Therefore betabeta decay of Te -130 has to be attributed mainly to the 2-nu channel.