Preliminary results on the search for 100Mo 2β decay to the first excited 0_1^+ level of 100Ru

Molybdenum sample with mass of near 1 kg, enriched in 100Mo at 99,5 %, is used to confirm or reject previous reports on observation of 2β2ν decay of 100Mo to the first excited 01+ level of 100Ru at E(01+) = 1130,5 keV. Data are collected in the low-background set-up with 4 HP Ge detectors, each of 225 cm3 volume, in the Gran Sasso Underground Laboratory (Italy). After 1927 h of measurements, the reached sensitivity to the half-life is ∼5 1020 y; it does not allow to make definite conclusions on existence of the process searched for. Further measurements are in progress

PRELIMINARY RESULTS ON THE SEARCH FOR 100Mo 2β DECAY TO THE FIRST EXCITED 0^+_1 LEVEL OF 100Ru (ARMONIA EXPERIMENT)

Molybdenum sample with mass of 1 kg, enriched in 100Mo at 99.5 %, is used to confirm or reject previous reports on observation of 2β2ν decay of 100Mo to the first excited 0^+_1 level of 100Ru (E_exc = 1130.5 keV). Data are collected in the low-background set-up with 4 HP Ge detectors, each of ~225 cm^3 volume, in the Gran Sasso underground laboratory of INFN (Italy). After more than 10000 h of measurements, number of events which are present in the coincidence spectrum corresponds to the half life value of T_1/2 = ~6 x 10^20 yr for 100Mo →100Ru* decay, in agreement with previous results. Further measurements are in progress

Search for rare processes at Gran Sasso

New results achieved by the DAMA collaboration on the search for rare processes in the underground Gran Sasso National Laboratories (LNGS) of the INFN are presented. In particular, the following searches have been summarized: i) search for the alpha activity of Eu-151; ii) measurement of 2 beta 2 nu decay of Mo-100 to the first excited 0(1)(+) level of Ru-100; iii) search for double beta processes ill Zn-64