New symmetry regions in the IBA and a simplified approach to nuclear phase transitions
The IBA treatment of nuclear symmetries and transition regions is discussed. A new, extensive region of O(6) nuclei near A = 130 is presented and compared with the Pt isotopes. Nearly identical level schemes characterize both regions, including similar relations between the O(6) and O(5) steps in the dynamical symmetry chain decomposition, and similar discrepancies with the O(6) limit. Simple calculations that incorporate a triaxial component as an O(6) symmetry breaking mechanism remove these discrepancies in both regions. The evidence for a new, and perhaps the only, good region of SU(3) symmetry is given and discussed in a context of mixing with non-collective degrees of freedom. Finally, a systematic approach to transition regions is presented in which the key determinant of structure is the product N/sub ..pi../.N/sub ..nu../ of the number of valence proton and neutron bosons. Recognition of this allows an extremely simple treatment of complex transition regions. As an example, calculations for the U(5)..-->..O(6)..-->..SU(3) sequence from A = 120-140, which involve only six constants for the entire region of approx. = 30 nuclei, are discussed. The use of N/sub ..pi../.N/sub ..nu../ plots allows the study of the dissipation of shell and subshell gaps. Results for the A approx. = 100 and A approx. = 150 regions are presented and effective proton-boson numbers are extracted and compared with earlier results from g factor measurements and from microscopic calculations. 43 references.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA); Koeln Univ. (Germany, F.R.). Inst. fuer Kernphysik
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5908986
- Report Number(s):
- BNL-35984; CONF-8410144-10; ON: DE85007928
- Resource Relation:
- Conference: International symposium on nuclear shell model, Philadelphia, PA, USA, 31 Oct 1984; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
Similar Records
IBA in deformed nuclei
0{sup +} states in the large boson number limit of the Interacting Boson Approximation model
Related Subjects
INTERACTING BOSON MODEL
SYMMETRY
DEFORMED NUCLEI
ENERGY LEVELS
HAMILTONIANS
INTERMEDIATE MASS NUCLEI
NUCLEAR STRUCTURE
O GROUPS
SU-3 GROUPS
U-6 GROUPS
DYNAMICAL GROUPS
LIE GROUPS
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
NUCLEAR MODELS
NUCLEI
QUANTUM OPERATORS
SHELL MODELS
SU GROUPS
SYMMETRY GROUPS
U GROUPS
653007* - Nuclear Theory- Nuclear Models- (-1987)