Rotational Bands in Rare-Earth Proton Emitters and Neighboring Nuclei

The anomalous proton-decay rates in 131Eu and 141Ho have been explained by the presence of large quadrupole deformation. Consistent with this hypothesis was the discovery of the decay branch in 131Eu to the 2+ state in the daughter nucleus. Direct evidence that 141Ho and 131Eu are deformed came from the observation of rotational bands. From the dynamic moment of inertia the deformation of β2=0.25(4) was deduced for the 141Ho ground state. The large signature splitting in the ground-state band in 141Ho indicates that Coriolis mixing plays an important role in this nucleus. The comparison between the Particle-Rotor Model and the data indicates that 141Ho has significant hexadecapole deformation and/or might be triaxial. The comparison between theory and experiment constrains other parameters used in the proton decay rate calculations from deformed nuclei such as the Coriolis interaction and pairing strength