High-spin states inAu188: Further evidence for nonaxial shape

The high-spin level structure of $^{188}\mathrm{Au}$ has been investigated via the $^{173}\mathrm{Yb}$($^{19}\mathrm{F}$,$4n$$\ensuremath{\gamma}$) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new ${I}^{\ensuremath{\pi}}={20}^{+}$ state associated with $\ensuremath{\pi}{h}_{11/2}^{\ensuremath{-}1}\ensuremath{\bigotimes}\ensuremath{\nu}{i}_{13/2}^{\ensuremath{-}2}{h}_{9/2}^{\ensuremath{-}1}$ configuration and two new rotational bands, one of which is built on the $\ensuremath{\pi}{h}_{9/2}\ensuremath{\bigotimes}\ensuremath{\nu}{i}_{13/2}$ configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around $^{188}\mathrm{Au}$ for the $\ensuremath{\pi}{h}_{9/2}\ensuremath{\bigotimes}\ensuremath{\nu}{i}_{13/2}$ bands in odd-odd Au isotopes. Evidence for $\ensuremath{\pi}{h}_{11/2}^{\ensuremath{-}1}\ensuremath{\bigotimes}\ensuremath{\nu}{i}_{13/2}^{\ensuremath{-}1}$ structure of nonaxial shape with $\ensuremath{\gamma}<\ensuremath{-}{70}^{\ifmmode^\circ\else\textdegree\fi{}}$ has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.