F-spin study of rare-earth nuclei using F-spin multiplets and angular momentum projected intrinsic states

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7296103

Diallo, A F

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/[Lambda]-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[sup +] 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 ([sup 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 [cflx T](M1) operator for determining the M1 strength.

• Research Organization: Arizona Univ., Tucson, AZ (United States)
• OSTI ID: 7296103
• Country of Publication: United States
• Language: English

Related Subjects

663110* -- General &amp; Average Properties of Nuclei &amp; Nuclear Energy Levels-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON-BARYON INTERACTIONS
EVEN-EVEN NUCLEI
GYROMAGNETIC RATIO
HADRON-HADRON INTERACTIONS
INTERACTING BOSON MODEL
INTERACTIONS
INTERMEDIATE MASS NUCLEI
ISOTOPES
LIE GROUPS
MATHEMATICAL MODELS
MULTIPLETS
NUCLEAR MODELS
NUCLEI
NUCLEON-NUCLEON INTERACTIONS
PARTICLE INTERACTIONS
PROTON-NEUTRON INTERACTIONS
PROTON-NUCLEON INTERACTIONS
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
SAMARIUM ISOTOPES
SHELL MODELS
SU GROUPS
SU-2 GROUPS
SYMMETRY GROUPS