First identification of excited states in 84–86Nb

We report on the observation of excited states in the niobium isotope with masses 84, 85 and 86. These nuclei lie in the shape transition region known to occur in nuclei with 35 less-than-or-equal-to Z less-than-or-equal-to 40 and N = 45. Unambiguous identification was achieved by detecting gamma-rays in coincidence with mass-separated recoils produced in heavy-ion fusion reactions. Rotational bands were observed in 84Nb and 85Nb which show decoupling schemes similar to those in the neighbouring nuclei. A rotational model was used to interpret these bands and the quasiparticle configurations involved. Two sequences of transitions were observed in 86Nb, at least one of which appears to be a rotational band.