New observation of a decay of ¹⁹⁰Pt to the first excited level of ¹⁸⁶Os

The partial half-life of 190Pt for the alpha decay to the first excited level (E-exc=137.2 keV) of (18)6Os was measured using an ultralow-background HPGe-detector system located 225 m underground in the laboratory HADES (Belgium). A sample of high purity platinum (the purity grade is 99.95%) with a mass of 148.122 g was used and measured during 373 days. Preliminary, the partial half-life of Pt-190 is estimated as T-1/2=[2.28(-0.16)(+0.19) (stat.)+/- 0.9( syst.)] x 10(14) yr.