Boson expansion theory description of anharmonic gamma vibrations in well deformed nuclei

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7142352

Stotts, S A

The boson expansion theory, which has been used extensively in the past in describing anharmonic vibrations in spherical nuclei, is used here to describe anharmonic gamma vibrations in well deformed nuclei, notably in {sup 168}Er. By using this theory we go beyond simple one-phonon calculations such as in the Random Phase Approximation. This must be done since, by the nature of the anharmonicities, it is not possible to simply take linear superpositions of one-phonon states to predict higher energy vibrational states. Starting from the Nilsson single particle deformed states, the fermion form of the problem is presented by using either the Tamm-Dancoff Approximation or the Random Phase Approximation as a basis. The interactions chosen are of a collective quadrupole type including both particle hole and pairing interactions. Also, similar to our previous boson expansion works, we consider the effects of noncollective terms on our collective interactions. This is treated in a perturbative fashion within the framework of the Feshbach formalism. In addition, we include some higher order interactions recently developed. Both the fermion and corresponding boson forms of these terms are developed here. Finally, based on some recent advances, the interaction strengths are now calculated instead of being used as free parameters. Numerical results of our theory are presented. As predicted from other works the potential energy surface exhibits a nonzero minimum. The energy states calculated agree well with the experimental values.

• Research Organization: Texas Univ., Austin, TX (USA)
• OSTI ID: 7142352
• Country of Publication: United States
• Language: English

Related Subjects

651000* -- Nuclear Physics
653001 -- Nuclear Theory-- Nuclear Structure
Moments
Spin
& Models
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BOSON EXPANSION
CALCULATION METHODS
DEFORMED NUCLEI
ENERGY LEVELS
ERBIUM 168
ERBIUM ISOTOPES
EVEN-EVEN NUCLEI
EXCITED STATES
INTERMEDIATE MASS NUCLEI
ISOTOPES
NUCLEI
RANDOM PHASE APPROXIMATION
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
STABLE ISOTOPES
TAMM-DANCOFF METHOD
VIBRATIONAL STATES