The yrast states in the neutron deficient $N=90\mathrm{}$ nucleus ${}^{166}\mathrm{Os}$ have been extended to $J\approx 12ħ$ (possibly $14ħ)$ and two sidebands have been established. Transitions in ${}^{165}\mathrm{Os}$ have been observed for the first time. These nuclei were populated using the ${}^{106}\mathrm{Cd}{(}^{64}\mathrm{Zn}{,2pxn)}^{168-x}\mathrm{Os}$ reaction at a beam energy of 334 MeV. The emitted $\gamma$ rays were detected with the Jurosphere $\gamma$-ray spectrometer, while the recoiling nuclei were identified using an active stopper at the focal plane of the gas-filled separator RITU by recoil decay tagging. The observed states are discussed in terms of the systematics of the osmium nuclei in the transitional region as the $N=82\mathrm{}$ shell closure is approached.

• Received 21 January 2002

DOI:https://doi.org/10.1103/PhysRevC.66.014309