Collective bands in 104,106,108 Mo

We have used our analysis of γ-γ-γ data (5.7 × 10 11 triples and higher folds) taken with Gammasphere from prompt γ rays emitted in the spontaneous fission of 252 Cf to study the collective bands in 104,106,108 Mo. The one-phonon and two-phonon γ -vibrational bands and known two-quasiparticle bands in neutron-rich 104,106 Mo were extended to higher spins. The one-and two-phonon γ -vibrational bands have remarkably close energies for transitions from the same spin states and identical moments of inertia. Several new bands are observed and are proposed as quasiparticle bands in 104,106 Mo, along with the first β -type vibrational band in 106 Mo. The quasiparticle bands have essentially constant moments of inertia near the rigid-body value that indicate blocking of the pairing interaction. Candidates for chiral doublet bands in 106 Mo are strong. These are the first reported chiral vibrational bands in an even-even nucleus.