AN INTERACTING BOSON MODEL OF CLUSTERING IN NUCLEI: ALPHA-PARTICLE CLUSTERING IN HEAVY NUCLEI (NUCLEAR STRUCTURE, SU(3) LIMIT, ALPHA-DECAY, E1 TRANSITIONS, ACTINIDES).

Abstract

A general interacting boson model of clustering in nuclei is presented. The model is then specialized to the case of n identical α-clusters [U(6) (CRTIMES) U(4)] , followed by a detailed study of the SU(3) dynamical limit. Many useful formulae are derived in this limit. The general problem of coexistence and configuration mixing is discussed, and a useful SU(3) bank mixing approximation (BMA) is presented. Formulae for the case of two mixed configurations are derived. The method of calculating the matrix elements for two-nucleon transfer reactions is demonstrated, and formulae for α-decay reduced widths are given. This model is then utilized for the study of the systematic trends of the data available for actinide nuclei. Most of the results presented here are for the well-deformed even-even mass actinides with A < 242; however, some trends in going to the spherical region and to larger A are studied. Tests, based on experimental data, are presented to discriminate between different limits of this model, and between this and other models. The limit of the model presented here satisfies all of the experimental tests found, while all other competing models were found to have serious deficiencies. This phenomenological study indicates that α-clustering effects are of fundamental importance for understanding the structure and dynamics of actinide nuclei. Suggestions for future research are made, some of which are based on preliminary work that has already been done.