Revised level scheme of 199Hg following Coulomb excitation

Abstract

γ-ray transitions of 199Hg were investigated following Coulomb excitation with oxygen ions at different bombarding energies. Angular distributions with and without coincidence with backscattered oxygen ions were measured. Ge(Li) γ-ray spectra were measured in triple coincidence with γ-rays and backscattered particles. A new level is reported at 413.5 keV and assigned a spin of 5 2 − . A spin of 3 2 − is assigned to the level at 403.4 keV instead of the 1 2 − spin previously. B(E2)↑ values measured relative to B(E2)↑ (158.37 keV) = 0.375(17) are 0.248(15), 0.170(20) and 0.099(16) for the 208.3, 403.4 and 413.5 keV transitions, respectively. The measured mixing ratios are —0.65(25) and +0.32(2) for the 208.3 ( 3 2 − → 1 2 −) and 403.4 ( 3 2 − → 1 2 −) keV transitions, respectively. The revised decay scheme is presented and discussed. The same experimental techniques were used to Coulomb excite 201Hg. No γ-ray transitions up to an energy of 1000 keV in coincidence with 60 million backscattered particles could be seen when an 85% 201Hg enriched target was bombarded with 33 MeV 16O ions.