High-K structures and triaxiality in 186Os Original Research Article

The high-spin structure of the stable nucleus 186Os has been studied, using a radioactive 14C beam. New rotational bands built on multi-quasiparticle states with Kπ = 5−, 7−, 9−, 10+ and 15+ are observed and the bandhead energies are compared to predictions of blocked BCS calculations. The first crossing of the ground-state band at View the MathML source, involving a high-Kt-band structure, is observed and explained using a two-band mixing model. The structure at higher angular momentum is dominated by intrinsic states, that exhibit a dramatic loss of isomerism. Potential-energy-surface calculations, with Lipkin-Nogami pairing, show these configurations to be triaxial, accounting for the breakdown in K conservation. The relation between the K projection and the total angular momentum is investigated for these non-axial states.