The proton-neutron Interacting-Boson Model contains both symmetric and mixed-symmetry proton-neutron boson configurations. These states of different proton-neutron symmetry can be classified in terms of an SU(2) symmetry, called F-spin. This dissertation deals with some new applications of F-spin. Even-even nuclei drawn from the proton and neutron shells 50 < Z < 82 and 82 < N < 126, respectively, are systematically classified in F-spin multiplets and their binding energies are fit with a six-parameter mass-formula. Using particle-hole symmetry conjugation, the energies of the low-lying levels of the neutron-rich nuclei are estimated and their mass excesses determined with the mass-formula. The masses of these nuclei are of interest in astrophysical processes. A novel asymptotic realization of the angular-momentum projected intrinsic-state in the generalized IBM is presented. This approach which uses the Laplace method of asymptotic expansion, is shown to be an improvement over the Gaussian method espoused by Kuyucak and Morrison. The method, herein called the 1/Λ-expansion, is used to derive analytical expressions for different quantities in the framework of the generalized IBM. Particular attention is paid to the M1 summed strength, the mean-excitation energy of the mixed symmetry 1⁺ scissor mode, and the gyromagnetic ratios of the ground-band members, for which formulas are derived. A no-free-parameter calculation is performed for the summed M1 strength and the centroid energy of ⁽¹⁴⁶⁻¹⁵⁸⁾Sm isotopes. The g factors of deformed and transitional nuclei in the rare-earth mass region are also computed. The data in all cases are found to be well reproduced, in general. A weak L dependence is predicted for the g factors, and there appears to be no need to include two-body terms in the T(M1) operator for determining the M1 strength.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/186290 |
| Date | January 1993 |
| Creators | Diallo, Abdoulaye Foula. |
| Contributors | Barrett, Bruce R., Kohler, Sigurd, Garcia, J.D., Donahue, Douglas J., McIntyre, Laurence C. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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