0{sup +} states in the large boson number limit of the Interacting Boson Approximation model
- Institute of Nuclear Physics, National Centre for Scientific Research 'Demokritos', GR-15310 Aghia Paraskevi, Attiki (Greece)
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520-8124 (United States)
Studies of the Interacting Boson Approximation (IBA) model for large boson numbers have been triggered by the discovery of shape/phase transitions between different limiting symmetries of the model. These transitions become sharper in the large boson number limit, revealing previously unnoticed regularities, which also survive to a large extent for finite boson numbers, corresponding to valence nucleon pairs in collective nuclei. It is shown that energies of 0{sub n}{sup +} states grow linearly with their ordinal number n in all three limiting symmetries of IBA [U(5), SU(3), and O(6)]. Furthermore, it is proved that the narrow transition region separating the symmetry triangle of the IBA into a spherical and a deformed region is described quite well by the degeneracies E(0{sub 2}{sup +}) = E(6{sub 1}{sup +}, E(0{sub 3}{sup +}) = E(10{sub 1}{sup +}), E(0{sub 4}{sup +}) = E(14{sub 1}{sup +}, while the energy ratio E(6{sub 1}{sup +})/E(0{sub 2}{sup +} turns out to be a simple, empirical, easy-to-measure effective order parameter, distinguishing between first- and second-order transitions. The energies of 0{sub n}{sup +} states near the point of the first order shape/phase transition between U(5) and SU(3) are shown to grow as n(n+3), in agreement with the rule dictated by the relevant critical point symmetries resulting in the framework of special solutions of the Bohr Hamiltonian. The underlying partial dynamical symmetries and quasi-dynamical symmetries are also discussed.
- OSTI ID:
- 21254835
- Journal Information:
- AIP Conference Proceedings, Vol. 1072, Issue 1; Conference: International conference on nuclear physics and astrophysics: From stable beams to exotic nuclei, Cappadocia (Turkey), 25-30 Jun 2008; Other Information: DOI: 10.1063/1.3039862; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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