High-spin structure and multiphononγvibrations in very neutron-richRu114

High-spin levels of the neutron-rich $^{114}\mathrm{Ru}$ have been investigated by measuring the prompt $\ensuremath{\gamma}$ rays in the spontaneous fission of $^{252}\mathrm{Cf}$. The ground-state band and one-phonon $\ensuremath{\gamma}$-vibrational band have been extended up to 14${}^{+}$ and 9${}^{+}$, respectively. Two levels are proposed as the members of a two-phonon $\ensuremath{\gamma}$-vibrational band. A back bending (band crossing) has been observed in the ground-state band at $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\approx}$ 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 $\ensuremath{\gamma}$-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.