The linear polarization of $\gamma$ rays in ${}_{}{}^{129}{}_{}{}^{}\mathrm{Ba}$ produced by the reaction ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},3n)$ was measured using a Compton polarimeter made of two Ge(Li) coaxial detectors. The results establish unambiguously the $h_{\frac{11}{2}}$ band structure and its separation into the $\tilde{\Omega }=j=\frac{11}{2}$ and $\tilde{\Omega }=j-1=\frac{9}{2}$ level subsystems. The existence of the $g_{\frac{7}{2}}$ band is shown for the first time in the mass region $A\approx 130$.

[NUCLEAR REACTIONS ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},3n)$, $E=52\mathrm{}$ MeV; measured linear polarization of $\gamma$ rays; deduced spins and parities of levels and multipole mixing ratios of transitions in ${}_{}{}^{129}{}_{}{}^{}\mathrm{Ba}$; triaxial shape.]

• Received 29 September 1977

DOI:https://doi.org/10.1103/PhysRevC.17.596