Shell model plus cluster description of negative parity states in 212Po

The intraband electromagnetic transitions in 210Po and 210Pb are well described within the shell model approach. In contrast, similar transitions in 212Po are one order of magnitude smaller than the experimental values, suggesting the existence of an α-cluster component in the structure of this nucleus. To probe this assumption we introduced Gaussian-like components in the single-particle orbitals. We thus obtained an enhancement of intraband transitions, as well as a proper description of the absolute α-decay width in 212Po. We analyzed the recently measured unnatural parity states I− in 212Po in terms of the collective octupole excitation in 208Pb coupled to positive parity states in 210Pb. They are connected by relatively large dipole transitions to yrast positive natural parity states. We described E1 transitions by using the same α-cluster component and an effective neutron dipole charge eν=−eZ/A. B(E2) values and absolute α-decay width in 212Po are simultaneously described within the shell model plus a cluster component depending upon one free strength parameter