High-spin levels of the neutron-rich ${}^{114}\mathrm{Ru}$ have been investigated by measuring the prompt $\gamma$ rays in the spontaneous fission of ${}^{252}\mathrm{Cf}$. The ground-state band and one-phonon $\gamma$-vibrational band have been extended up to 14${}^{+}$ and 9${}^{+}$, respectively. Two levels are proposed as the members of a two-phonon $\gamma$-vibrational band. A back bending (band crossing) has been observed in the ground-state band at $\hslash \omega \approx$ 0.40 MeV. Using the triaxial deformation parameters, the cranked shell model calculations indicate that this back bending in ${}^{114}\mathrm{Ru}$ should originate from the alignment of a pair of $h_{11/2}$ neutrons. Triaxial projected shell model calculations for the $\gamma$-vibrational band structures of ${}^{114}\mathrm{Ru}$ are in good agreement with the experimental data. However, when using the oblate deformation parameters, both of the above-calculated results are not in agreement with the experimental data.

• Received 18 February 2011

DOI:https://doi.org/10.1103/PhysRevC.83.054317