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Abstract: A sample of 100MoO3 powder with molybdenum enriched in 100Mo to 99.5% and mass of 1199 g was measured for 18120 h in a low-background set-up with 4 HP Ge detectors ( volume each one) deep underground (3600 m w.e.) at the Laboratori Nazionali del Gran Sasso of the INFN (Italy). The two γ quanta of 540 keV and of 591 keV emitted in the deexcitation process after a decay of 100Mo to the excited level of 100Ru () are observed in the accumulated data both in coincidence and in the 1-dimensional sum spectrum. The measured half life is: , well in agreement with positive results obtained in previous experiments. Moreover, the limit on charge non-conserving β decay of 100Mo is also set: at 90% C.L.; it corresponds to the limit on CNC admixture in weak currents: . [ABSTRACT FROM AUTHOR]

Abstract: Lead tungstate (PbWO4) crystal scintillators are discussed as an active shield and light guides in 116Cd double-beta decay experiment with Cadmium tungstate (CdWO4) scintillators. Scintillation properties and radioactive contamination of PbWO4 scintillators were investigated. Energy resolution of CdWO4 detector, coupled to PbWO4 light guide, was tested. Efficiency of PbWO4-based active shield to suppress background from the internal contamination of PbWO4 crystals, as well as possible contribution from radioactivity of copper shield and phototubes were calculated. Using of lead tungstate crystal scintillators as high-efficiency active shield could allow to build sensitive experiment to search for decay of 116Cd with 116CdWO4 crystal scintillators. [Copyright &y& Elsevier]