Microscopic structures of the low-lying nonrotational (intrinsic) states in the odd-odd nucleus ${}_{63}{}^{156}{}_{}{}^{}\mathrm{Eu}_{93}^{}{}_{}{}^{}$ are investigated using the quasiparticle-phonon nuclear model Hamiltonian including the pairing, quadrupole-quadrupole, octupole-octupole, and residual p-n interactions. The extent of vibrational admixtures to the two-quasiparticle configurations and the intrinsic matrix elements of electric octupole operator for the ‘‘same K opposite parity’’ bands are examined to conclude that, contrary to some recent suggestions, the low-energy ${}_{}{}^{156}{}_{}{}^{}\mathrm{Eu}$ spectrum does not contain ‘‘parity doublets’’ characteristic of reflection asymmetric shapes, in contrast with the structures seen in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Eu}$ and ${}_{}{}^{154}{}_{}{}^{}\mathrm{Eu}$.

• Received 8 May 1992

DOI:https://doi.org/10.1103/PhysRevC.46.2311