New limits on double-beta decay of 190Pt and 198Pt
Abstract
A search for double-beta decay of 190Pt and 198Pt with emission of γ-ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of 190Pt relative to different channels and modes of the decays were set on the level of T1/2 1014-1016 yr. A possible exact resonant 0 KN transition to the 1,2 1326.9 keV level of 190Os is limited for the first time as T1/2 ≥ 2.5 ×1016 yr. A new lower limit on the double-beta decay of 198Pt to the first excited level of 198Hg was set as T1/2 ≥ 3.2×1019 yr, one order of magnitude higher than the limit obtained in the previous experiment.