The search for the possible resonant 0ν2ε capture to the 1382.4 keV level
search for 2β transition of 198Pt to the 411.8 keV excited level of 198Hg was carried out at
the first time.
In the Table 2 (click it to enlarge), we present half-life limits on 2β processes in 190Pt and 198Pt isotopes. The energies of the γ lines (Eγ), which were used to set the T1/2 limits, are listed in column 4 with the corresponding efficiencies (η) in column 5. T1/2 limits are derived in the present work at 90% C.L., while the limit from [1,2] is given at 68% C.L.
In particular, a possible resonant double electron capture in 190Pt was restricted on the level of 2.9 x 1016 yr at 90% C.L. In addition, T1/2 limit on 2β- decay of 198Pt (2ν + 0ν) to the 2+1 excited level of 198Hg has been set at the first time: T1/2 > 3.5 x 1018 yr. The radiopurity level of the used platinum sample is reported.