New multi-phonon gamma vibrational bands in A∼110 neutron-rich nuclei

The high spin states of neutron-rich 103 Nb, 107 Tc and 109 Tc nuclei in A ∼110 region have been investigated by measuring prompt γ-γ-γ coincident measurements populated with the spontaneous fission of 252 Cf with the Gammasphere detector array. In 103 Nb, one-phonon K = 9/2 and two-phonon K = 13/2 γ-vibrational bands have been identified. In 107 Tc and 109 Tc, one-phonon K = 11/2 and two-phonon K = 15/2 γ-vibrational bands, in which the zero-phonon bands are based on K =7/2 excited states, have also been identified. The two-phonon bands are first observed in odd- Z nuclei. The characteristics for these band structures have been discussed.