A #betta#-spectroscopic study of the structure of medium-heavy nuclei far from beta stability

The aim of this study is to extend the existing nuclear spectroscopic information in the Zapprox.=50 isotopes near the stability line, to the proton-rich ''white'' region of the nuclide chart. This has been done with respect both to the coexistence of single particle states and collective rotational bands and to the strength distribution in the beta decay. The beta strength function is of general importance for various fields in nuclear physics and astrophysics. In the first part of this work, investigations of high spin states in neutron deficient nuclei around Z=50 by #betta#-spectroscopic methods are described. High spin states in 108Sn, 107In and 108In were studied by the reaction 92Mo(19F,xyz#betta#). The experiments were performed at the MP Tandem accelerator at the Max-Planck-Institut fuer Kernphysik in Heidelberg. For the reduction of the Compton background in the spectra a Compton suppression spectrometer was used. A large number of new high spin states has been found in the studied nuclei and the systematic behaviour of the level pattern is discussed. In sup(107,108)In rotational-like band structures are observed whereas the yrast states in 108Sn are suggested to be four-quasiparticle states. In the second part the results from a #betta#-spectroscopic study of the #betta#+ strength function Ssub(#betta#)+ are presented for the #betta# decay of neutrondeficient Ba and Cs nuclei. Information on the structure of Ssub(#betta#) existed up to now for the Ba isotopes, only beyond the proton binding energy from #betta#-delayed proton experiments. The beta decay of 121Ba, 123Ba, sup(120m+g)Cs and sup(121m+g)Cs was studied by the reactions sup(92,94)Mo(32S,xyz#betta#). For these nuclei a total number of about 150 new #betta# transitions has been identified in this work. The observed shapes of Ssub(#betta#) are consistent with the structure expected from shell model and RPA calculations. (orig.)