Shell structure from N=Z (100Sn) to N>>Z (78Ni)

The shell structure of 100Sn shows striking resemblance to 56Ni one major shell below. Large-scale shell model calculations employing realistic interactions derived from effective NN potentials and allowing for up to 4p4h excitations of the 100Sn core account very well for the spectroscopy of key neighbours 102,103Sn, 98Cd and 94Ag, as inferred from level energies, isomerism, E2 strengths and Gamow-Teller (GT) decay of high-spin states. Recent β- decay studies of 101-104Sn using the sulphurisation ISOL technique open the perspective to study the 100Sn GT resonance. At N>>Z the persistence of the N=50 and the weakness of the N=40 shells are traced back to the monopole interaction in S=0 proton-neutron (πν) pairs of nucleons, a scenario which can be generalised to account for the new N=6,16(14),34(32) magicity in light neutron-rich nuclei. (orig.)