First search for double beta decay of platinum by ultra-low background HP Ge spectrometry,

A search for double- processes in 190Pt and 198Pt was realized with the help of ultra-low background HP Ge 468cm^3 spectrometer in the underground Gran Sasso National Laboratories of the INFN (Italy). After 1815 h of data taking with 42.5g platinum sample, T 1/2 limits on 2 processes in 190Pt ( + and 2 have been established on the level of 1014-1016y, 3 to 4 orders of magnitude higher than those known previously. In particular, a possible resonant double-electron capture in 190Pt was restricted on the level of 2.9×1016 y at 90% C.L. In addition, T 1/2 limit on 2− decay of 198Pt (2 +0) to the 2+ 1 excited level of 198Hg has been set at the first time: T 1/2 > 3.5×1018 y. The radiopurity level of the used platinum sample is reported