Systematic Study On Deformation And Rotational Properties Of Even-even Nuclei

The main work of this dissertation is to systematically study the structure properties of rotating nuclei in three-dimensional deformation space(β2,γ,β4)based on the pairing-deformation self-consistent total-Routhian-surface(TRS)method within the framework of macroscopic-microscopic model and one dimensional cranking approximation.The main content includes two parts:one is to investigate the effects of different deformation degrees of freedom and rotation on nuclear structure,including the evolution properties of single-particle levels,pairing corrections,shell corrections,macroscopic energy,the energy due to cranking,etc;the other is to systematically reveal the rotational properties in even-even nuclei across the nuclear chart,providing various physical quantities,e.g.,nuclear deformations,pairing gaps,aligned angular momenta and excitation energies,in the Z-N plane and discussing the evolution properties briefly.The microscopic structure and property of a nucleus is primarily determined by the single-particle levels,especially the ones near the Fermi level.In this project,taking the nucleus 142Dy as an example,we investigate the single-particle structure and its evolution with respect to deformation degrees of freedom and rotational frequency based on the realistic deformed Woods-Saxon potential.Typical two-dimensional maps of the total nuclear energy are presented as well.It is found that both deformations and cranking may rearrange the single-particle levels to some extent.The time reversal symmetry of the Hamiltonian is broken under rotation,leading to the signature splitting of the single-particle levels.As expected,one can see that Coriolis force can strongly affect the high-j low-Ω orbitals.In addition,we also investigate the evolution properties of shell correction,pairing correction,cranking correction and macroscopic energy with the aid of the standard Strutinsky method,Lipkin-Nagami method,the principal-axis cranking approximation and standard liquid-drop model.The systematic and large-scale calculations can help discovering the systematic laws of structural evolution,checking and developing nuclear models and providing relatively reliable information for experiments.Prior to this work,numerous systematic studies on nuclear ground-state properties have been carried out by some authors.However,the systematic studies on nuclear high-spin states are relatively scarce.To our knowledge,Werner et al an Deleplanque et al have systematically calculated the high-spin properties but the pairing was ignored.In the present work,we performed the systematic investigation on nuclear high-spin properties and their evolution based on the pairing-deformation self-consistent TRS calculation.It is found that the pairing effect is of importance on the nuclear properties,e.g.,the moments of inertia,especially before and near the spin domain of the backbending.Before displaying the global results,we firstly investigated the rotational characteristics of different isotopic-chains,e.g.,in the rare-earth region by confronting our calculations with available experimental data and other accepted theories,indicating that the present results are reasonable and correct to a large extent.Then,we systematically investigated 766 even-even nuclei with Z≥20(identified in experiment)across the nuclear chart,focusing on the deformations,pairing gaps,aligned angular momenta(equivalent to the moments of inertia),excitation energies,etc and their evolution with changing nucleon number and rotational frequency.Such a synthetic presentation,which to some extent can overcome and eliminate the bias among different theoretical models,will be helpful when planning high-spin experiments,especially in the data-scarce drip-line or superheavy regions.