High-spin states in the doubly odd nucleus ${}_{}{}^{138}{}_{}{}^{}\mathrm{Pm}$ have been studied via gamma-ray spectroscopic methods following the ${}_{}{}^{116}{}_{}{}^{}\mathrm{Cd}$${(}^{27}$Al,5nγ) heavy-ion fusion-evaporation reaction. Several rotational bands have been populated in the nucleus. The yrast cascade is based on two signature components of the π${\mathit{h}}_{11/2}$⊗ν${\mathit{h}}_{11/2}$ configuration. A sideband was observed, which is probably based on the π[413]5/$2^{+}$⊗ν${\mathit{h}}_{11/2}$ configuration. Similar rotational bands built on these configurations have been observed in the neighboring doubly odd ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pr}$ and ${}_{}{}^{136}{}_{}{}^{}\mathrm{Pm}$ nuclei. An additional ΔI=2 band structure, not observed in these other nuclei, has also been populated. At low rotational frequencies, this band is possibly based on the π${\mathit{h}}_{11/2}$⊗ν[400]1/$2^{+}$ configuration. At a frequency ħω∼0.31 MeV it is crossed by a band based on the favored signature of the π${\mathit{h}}_{11/2}$⊗ν${\mathit{i}}_{13/2}$ configuration with an accompanying gain in alignment of ∼6ħ.

• Received 14 March 1989

DOI:https://doi.org/10.1103/PhysRevC.42.541