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

"9"8_4_8Cd_5_0 - The two-proton hole spectrum in "1"0"0_5_0Sn_5_0

Excited states in "9"8Cd, two proton holes from "1"0"0Sn, were identified and studied for the first time, using in-beam spectroscopy with highly selective ancillary detectors. The structure of the (#pi#g_9_/_2)"-"2 two proton hole spectrum below a T_1_/_2=0.48(16) #mu#s isomer is deduced and compared to shell model predictions. A tentative I"#pi#=(8"+) assignment, as suggested by systematics, yields a strongly reduced B(E2.8"+#->#6"+)=0.44(_-_1_0"+"2"0) W.u., corresponding to an effective proton charge of #epsilon#_#pi#=0.85(_-_1_0"+"2"0) #epsilon#, which is at variance with existing theoretical predictions. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Present status and future aspects of nuclear structure close to "1"0"0Sn

The present status of experimental approach to "1"0"0Sn in the spectroscopy of excited states is landmarked by the T_z=3/2 nuclei between "9"5Pd and "1"0"1In and the T_z=1 nuclei "9"4Pd and "9"8Cd. The detection limits with Pre-EUROBALL #gamma#-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 "1"0"0Sn, which shows a remarkable similarity to "5"6Ni. 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 "1"0"0Sn are discussed. (orig.)SIGLEAvailable from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman