SINGLE-PARTICLE STRUCTURE EFFECT ON HIGH-SPIN NUCLEAR STATES

Abstract
The woods-Saxon deformed potential is used to generate single particle states. The optimisation of the potential parameters on the basis of existing empirical data for heavy and medium heavy nuclei is presented. The results of the optimisation procedure for deformed nuclei are also discussed in the framework of the microscopic approach. Single particle spectra are used to generate high spin states of spherical and nearly spherical nuclei around ²⁰⁸Pb and ¹⁴⁶Gd. The shell-correction plus particle-hole analysis is shown to give the same single particle configurations as those obtained from shell model calculations for spins I ≲ 25 ñ, thus demonstrating the correctness of the method. The natural extension of the method to regions beyond the application of the shell model, i.e. to higher spins and possibly to large deformations, is discussed. An attempt is made to search for remains of regularities in the typically irregular spectra of yrast trap nuclei. In this context the appearance of high-spin yrast isomers and their possible decay modes, also the frequently observed single-particle E2 transitions, are discussed. The importance of the single-particle nuclear structure on the backbending and multi-backbending effects in nuclei is illustrated. In particular, some results of the Hartree-Fock-Bogolyubov (HFBC) method for double-backbending and the side band structure are given in connection with their dependence on the single particle structure in nuclei. Some difficulties due to uncertainties in the single-particle spectra are pointed out.