Production and decay properties of the lightest osmium isotopes

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 separator MARA 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.