The level structures of the doubly-odd nuclei ${}_{}{}^{136}{}_{}{}^{}\mathrm{Pm}$ and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pr}$ have been studied to high spin following the reactions ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$${(}^{27}$Al,5n${)}^{136}$Pm, ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$${(}^{24}$Mg,p3n${)}^{136}$Pm, and ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$${(}^{27}$Al,α3n${)}^{134}$Pr. The two nuclei show very similar collective features. In both nuclei a rotational band built on the π$h_{11/2}$⊗ν$h_{11/2}$ configuration has been observed. This band shows a constant signature splitting of ∼50 keV with no backbend in both cases. In addition, a sideband built on the π${\left[413\right](5/2\mathrm{}}^{+}$⊗ν$h_{11/2}$ configuration has been observed in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Pm}$. This band becomes yrast at high spins and shows a gain in alignment of ∼8ħ at a frequency of ħω∼0.28 MeV due to the decoupling of a pair of $h_{11/2}$ protons. In ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pr}$ the sideband was only observed above the band crossing. Experimental ratios of reduced transition probabilities, B(M1)/B(E2), have been extracted from transitions within the bands and compared to theoretical values obtained from a semiclassical model.

• Received 15 June 1987

DOI:https://doi.org/10.1103/PhysRevC.36.1810