Application and description of the Interacting Boson Model

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5161092

Duval, P D

A review of the principles and phenomenology of the IBM is presented. The basic IBM is then applied to the even tungsten isotopes and compared with experimental observables associated with the low-lying states. These observables include transition rates, branching ratios, /rho/(EO) values, quadrupole moments of the first two excited 2+ states, two-neutron separation energies, and isomer and isotope shifts. The results are seen to agree very well with the experimental data. Following the study of the tungsten isotopes an extension of the IBM to describe configuration mixing is presented. A specific example using the light mercury isotopes and the molybdenum isotopes is given. The IBM is then examined from a microscopic point of view, using the generalized seniority scheme. The structure of the bosons of the IBM is given in terms of correlated fermion pairs. Predictions for the IBM parameters are obtained by constructing the zeroth-order image of the corresponding fermion operator. The predictions of a single j-shell approximation are compared with empirical results. In this approximation the valence nucleons are assumed to occupy a single j-shell whose effective j value is chosen so as to reproduce the total occupancy of the valence shell. Next, the predictions of a two nondegenerate j-shell approximation are compared with empirical results. This approximation appears to be valid in both the 50-82 and the 82-126 neutron shells whose single-particle levels seem naturally to form two sub-shells. Finally, a brief description of the Interacting Boson-Fermion Model is given. This model is seen to be very successful in describing nuclei with an odd number of protons or neutrons. A calculation of the energy spectrum of the odd tungsten isotopes is presented.

• Research Organization: Arizona Univ., Tucson (USA)
• OSTI ID: 5161092
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BRANCHING RATIO
DOCUMENT TYPES
ENERGY LEVELS
ENERGY-LEVEL DENSITY
INTERACTING BOSON MODEL
ISOTOPES
MATHEMATICAL MODELS
MERCURY ISOTOPES
MOLYBDENUM ISOTOPES
NUCLEAR MODELS
QUADRUPOLE MOMENTS
REVIEWS
SHELL MODELS
TUNGSTEN ISOTOPES