Gamma decays from high-spin states in the A=51 mirror-pair "'Mn and "Fe, and the A=53 mirror pair 53Fe and 53 Co have been observed up to, and in one nucleus beyond, the fä band terminating states. For "Fe and 53Co, this represents the first observation of states of this type. The nuclei were studied in two GAMMASPHERE experiments with the addition of the FRAGMENT MASS ANALYSER recoil separator and an ion chamber at Argonne National Laboratory in Chicago, Illinois; and the MICROBALL light charged particle detector and the NEUTRON SHELL neutron detector system at Lawrence Berkeley National Laboratory in Berkeley, California. The observation of these isobaric analogue states allowed a detailed comparison of the level energies in each mirror pair. The mirror nuclei have the same mass number, but differing numbers of protons and neutrons. Thus, any difference in excitation energies can be interpreted as being due mainly to the Coulomb interaction, leading to a Coulomb Energy Difference (CED) plot as a function of angular momentum. The changes of the CED with spin have been interpreted in terms of the spatial arrangement of the valence protons, from rotational alignments and the effects of proton-proton recoupling. The observed level energies and the CED have been compared with the results of full pf shell-model calculations, with the Coulomb interaction included via the Coulomb Matrix Elements (CME). This comparison has allowed a detailed understanding of the microscopic mechanisms behind the changes in the CED. The CME were investigated in a fit to the A=53 CED, which revealed an anomalously high and counter-intuitive J=2 component. Extensive results from the study of these CME have been presented, including their role in the evolution of the CED, the physical meaning of the matrix elements themselves, and in particular the origin of the J=2 anomaly.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:273018 |
| Date | January 2003 |
| Creators | Williams, Scott James |
| Publisher | Keele University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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