Present status and future aspects of nuclear structure close to 100 Sn

The present status of experimental approach to 100 Sn in the spectroscopy of excited states is landmarked by the T z =3/2 nuclei between 95 Pd and 101 In and the T z =1 nuclei 94 Pd and 98 Cd. The detection limits with Pre-EUROBALL γ-arrays and ancillary detectors are below the 10 −5 level of the total fusion- evaporation residue cross section. A large scale shell model analysis of the existing data reveals the shell structure at 100 Sn, which shows a remarkable similarity to 56 Ni. Evidence for an increasing proton-neutron interaction in approaching the N=Z line is deduced from high spin isomers and spherical yrast lines. The effective E2 operator for protons and neutrons and implications for a low lying particle-hole (ph) E2 excitation in 100 Sn are discussed.