A Trilogy of Mass A=61 : Superdeformed Structures, Exotic Decay, and Isospin Symmetry

Sammanfattning: Three nuclei with mass number A=61 have been studied using four fusion-evaporation experiments carried out at the Oak Ridge, Argonne and Lawrence Berkeley National Laboratories. Normally deformed states in 61Ga were for the first time ever explored and in addition the experimental knowledge of the mirror nucleus 61Zn was extended. The two nuclei together provide the possibility to explore mirror symmetries and isospin breaking effects in medium-heavy nuclei. Moreover an indication of a prompt proton decay was observed in 61Ga which adds further complexity to the isospin symmetry studies. The normally deformed structures in the two nuclei are compared to the predictions from spherical shell-model calculations using different nuclear interactions. The comparison indicates the importance of the included subshells in the interaction and also the influence of the number of active particles in the calculations. High-spin states in 61Zn and 61Cu have been studied and the previously published level schemes have been greatly extended for both nuclei in the current analysis. In total thirteen rotational structures dominated by quadrupole transitions and five dominated by dipole transitions have been found in the two nuclei. Each structure is compared to predictions from cranked Nilsson-Strutinsky calculations and associated with certain predicted configurations. The general agreement with the predictions is good but the results may be further enhanced if modifying the standard Nilsson parameters. Suggestions on how to improve the agreement are given and first results are also indicated in the thesis.