Triaxial shape and onset of high-spin bands in 129Ba

High-spin states in ¹²⁹Ba have been studied by the ¹²⁰Sn(¹²C, 3n)¹²⁹Ba reaction. The onset of a system of bands parallel to the yrast band is observed. The negative parity states ($\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{system}$) break up into two substructures based upon the lowest $\text{I = j =}\text{11}\text{2}\text{and the}\text{I = j ? 1 =}\text{9}\text{2}$ states. In addition to the $\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ system, a new positive parity structure is seen which is built on the $\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{shell}$. The results are in qualitative agreement with the triaxial core model.