High-spin states in Au-188: Further evidence for nonaxial shape

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