Multiparticle excitations and identical bands in the superdeformed Gd149 nucleus

Eight superdeformed rotational bands have been observed in the Gd149 nucleus. Several excited bands have partners in neighboring nuclei which differ by up to four nucleons, with nearly identical dynamic moments of inertia and quantized γ-ray phasing. These observations cannot be easily explained by theoretical models including an intrinsic scaling with mass of the moment of inertia. A paired backbend and an interaction due to an accidental degeneracy between two superdeformed levels have also been observed.