Prompt γ-ray spectroscopy of theMo104andMo108fission fragments

The level structures of the neutron-rich ${}_{}{}^{104}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{108}{}_{}{}^{}\mathrm{Mo}$ nuclei have been investigated by observing prompt γ rays emitted in the spontaneous fission of ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ with the EUROGAM spectrometer. Levels with spins up to 12ħ have been observed and γ branching obtained. The data can be satisfactorily described when ${}_{}{}^{104,108}{}_{}{}^{}\mathrm{Mo}$ are considered as axially symmetric nuclei: in ${}_{}{}^{104}{}_{}{}^{}\mathrm{Mo}$, rotational bands based on the ground state, the one-phonon and the two-phonon γ-vibrational states and a quasiparticle state have been observed, whereas in ${}_{}{}^{108}{}_{}{}^{}\mathrm{Mo}$ the information is limited to the yrast band and the one phonon γ band. © 1996 The American Physical Society.