The α-decay properties of ${}_{}{}^{155}{}_{}{}^{}\mathrm{Lu}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Lu}$ show that their ground states are not π${\mathit{h}}_{11/2}$ (as they are in ${}_{}{}^{153,155}{}_{}{}^{}\mathrm{Tm}$, and ${}_{}{}^{151,153}{}_{}{}^{}\mathrm{Ho}$) but either π${\mathit{d}}_{3/2}$ or ${\mathrm{\pi }}_{1/2}$. From single-particle level systematics the π${\mathit{d}}_{3/2}$ assignment is favored. Calculations using the shell correction method predict the one-quasiparticle proton states based on the ${\mathit{h}}_{11/2}$, ${\mathit{d}}_{3/2}$, and ${\mathit{s}}_{1/2}$ subshells to appear very close in energy in Lu, Ta, and Re nuclei with N∼84, independently of equilibrium deformation.

• Received 2 April 1993

DOI:https://doi.org/10.1103/PhysRevC.48.R978