Collective Bands in Neutron-Rich ¹¹⁰Ru Nucleus

High spin states in neutron-rich ¹¹⁰Ru nucleus have been investigated by measuring high-fold prompt γ-ray coincidence events of the spontaneous fission of ²⁵²Cf with the Gammasphere detector array. The ground-state band and the γ-vibrational band have been confirmed and extended with spin up to 18ħ and 13ħ, respectively. The other three side bands, two proposed as two-quasiparticle bands and one proposed as a four-quasiparticle band,have been observed for the first time. The possible configurations for the quasi-particle bands are discussed. The cranked shell model calculations show that ¹¹⁰Ru nucleus may have oblate triaxial deformation with parameters β₂ = -0.30 and γ = 24°, and the band crossing in the yrast band is due to the alignment of a pair of h_11/2 neutrons.