Excited states of the Z=61 isotopes ${}_{}{}^{144}{}_{}{}^{}\mathrm{Pm}_{83}^{}{}_{}{}^{}$ and ${}_{}{}^{154}{}_{}{}^{}\mathrm{Pm}_{84}^{}{}_{}{}^{}$ have been studied in the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$${+}^{130}$Te reaction at a beam energy of 85 MeV. Gamma-ray and conversion electron spectroscopy were used to establish the high spin states of ${}_{}{}^{144}{}_{}{}^{}\mathrm{Pm}$ up to spin 20ħ and to extend the level spectrum of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Pm}$ up to a tentative spin of 33/2ħ. Empirical shell model calculations in a configuration space truncated to the π1${\mathit{h}}_{11/2}$, π1${\mathit{g}}_{7/2}^{\mathrm{-}1}$, and π2${\mathit{d}}_{5/2}^{\mathrm{-}1}$ protons and the ν2${\mathit{f}}_{7/2}$ neutron outside the ${}_{}{}^{146}{}_{}{}^{}\mathrm{Gd}$ core reproduce the observed energy levels in good agreement with the experimental results. (π${\mathit{h}}_{11/2}$${)}^2$ configurations are suggested in an N=83 isotone for Z<64.

• Received 29 January 1993

DOI:https://doi.org/10.1103/PhysRevC.47.2586