Gamma Vibrational Bands and Chiral Doublet Bands in A≈100 Neutron-rich Nuclei

The level structures of neutron-rich 105Mo,106Mo,108Mo and 110Ru nuclei in A ≈ 100 region have been carefully investigated by coincidence measurements of the prompt γ-rays populated in the spontaneous fission of 252Cf with the Gammasphere detector array. In 105Mo,one-phonon K=9/2 and two-phonon K=13/2 γ-vibrational bands have been identified. In 108Mo,one-phonon γ-vibrational band is expanded and two-phonon γ-vibrational band has been identified. Two similar sets of bands in 106Mo and 110Ru are observed to high spins,which have been proposed as the soft chiral γ-vibrational bands. The characteristics for these γ-vibrational bands and chiral doublet bands have been discussed.