Octupole deformation at high spin in the Ba-Sm region

Experimental evidence is presented for stable octupole deformation at high spin in ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ and possibly other rare earth nuclei based on the evolution with increasing spin of the $K^{\pi }=0^{+} \mathrm{and} 0^{-}$ bands into a single band. Comparisons and contrasts in the corresponding band evolutions are presented between the 88 and 90 isotones in the rare earths, and 88 and 90 protons (Ra and Th isotopes) in the actinides where stable octupole deformation is established.