Production and decay properties of the lightest osmium isotopes

Abstract

The production of 159,160,161Os and 159,160,161Re was investigated in experiments performed at the Accelerator Laboratory of the University of Jyväskylä. The nuclei of interest were produced using fusion-evaporation reactions induced by beams of 275–353 MeV 58Ni ions bombarding a 106Cd target. The evaporation residues were separated in flight using the recoil separatorMARA and implanted into a double-sided silicon strip detector, which was used to measure their decays. Cross sections for the production of these nuclides were measured and the relative population of the 8+ isomeric states and ground states of the N=84 isotones 156Hf, 158W, and 160Os were deduced. New decay chains assigned to 160Os were identified at beam energies of 310 and 330 MeV. These findings are compared with previous studies claiming the observation of 160Os and 156W. The α decays of 161Os were observed, confirming previous results for this nuclide and its β-decaying daughter, 157W. The α-decay branch of 159Re was also confirmed, but no delayed decays of this nuclide were observed that would be a signature of the β decays of the as yet unknown nuclide 159Os.