First observation of excited states in the neutron deficient nuclei<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>164</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Os</mml:mi></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>166</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Os</mml:mi></mml:math>

Excited states have been observed for the first time in the neutron deficient nuclei ${}^{166}\mathrm{Os}$ and ${}^{164}\mathrm{Os}.$ The nuclei were produced using the reactions ${}^{106}\mathrm{Cd}{(}^{63}\mathrm{Cu}{,p2n)}^{166}\mathrm{Os},$ ${}^{112}\mathrm{Sn}{(}^{58}\mathrm{Ni}{,2p2n)}^{166}\mathrm{Os},$ and ${}^{106}\mathrm{Cd}{(}^{60}\mathrm{Ni}{,2n)}^{164}\mathrm{Os}$ at beam energies of 292, 286, and 257 MeV, respectively. The $\ensuremath{\gamma}$ rays emitted by ${}^{166}\mathrm{Os}$ and ${}^{164}\mathrm{Os}$ were identified by correlating the associated recoil evaporation residues with their subsequent characteristic \ensuremath{\alpha} decays. The deduced level schemes indicate that ${}^{166}\mathrm{Os}$ and ${}^{164}\mathrm{Os}$ continue the trend of decreasing deformation moving away from the $N=104$ midshell. The level energy systematics of the low-spin states are presented.

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