Nuclear structure near the doubly-magic "1"0"0Sn

The single particle (hole) energies in "1"0"0Sn, as extrapolated by a shell model analysis of the neighbouring nuclei, show a remarkable similarity to those in "3"6Ni, one major shell lower. This is borne out in nearly identical I"#pi#=2"+ excitation energies, implying E(2"+)#approx =#3 MeV in "1"0"0Sn, and a large neutron effective E2 charge #epsilon##>=#1.6#epsilon#. In contrast a small proton polarisation charge #delta##epsilon##<=#0.3#epsilon# is found, pointing to a large isovector charge. Mean field predictions for single particle energies show substantial deviations from the experimental extrapolation. From the experimental two-proton hole spectrum in "9"8Cd an improved empirical interaction is extracted for the #pi#(p_1_/_2,g_9_/_2) model space yielding a good description of the N=50 isotones "9"5Rh to "9"8Cd. In "1"0"4Sn, for the first time in this region, strong E3 transitions with B(E3)#>=#17 W.u. were identified, indicating E(3"-)#approx =#3 MeV in "1"0"0Sn. New experimental devices, as the Ge-cluster cube and total absorption spectrometers, applied in a pioneering experiment to the #beta#"+/EC decay of "9"7Ag, have led to a consistent picture of the Gamow-Teller quenching around "1"0"0Sn. The experimental results are discussed in the framework of various shell model approaches by using both empirical and realistic interactions. (orig.)Available from TIB Hannover: RO 801(98-62) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman