Theoretical Studies On Nuclear Structure By The Elastic And Quasielastic Electron Scattering

The nucleus is an important level of the microscopic material structure.The theoretical study on the nuclear structure is an essential topic in nuclear physics.It has been proved that the electron scattering is an effective method to explore the nuclear structure,which can be used to extract many nuclear properties,such as the nuclear density distributions,charge radii,and so on.In this paper,the nucleon density distributions and momentum distributions of nuclei are analyzed by the elastic and quasielastic electron scattering,respectively.Based on these studies,the nuclear deformation and cluster structures are further studied.To begin with,the electron scattering off spherical and deformed nuclei is studied by combining the Hartree Fock Bogolyubov(HFB)model with the distorted wave Born approximation(DWBA)method.The Coulomb form factors of the representative spherical and deformed nuclei are calculated and compared with the experimental data,which verifies the validity of the deformed HFB model for the descriptions of the nucleon density distributions.To further analyze the effects of nuclear deformation on electron scattering,in this paper,the Coulomb form factors of even-even Xe isotopes and odd-A Cs isotopes are calculated by the spherical and deformed scattering models.The results show that for Xe isotopic chains,there are noticeable outward and downward trends in the form factors with the increasing of nuclear deformation,compared with the results from the spherical scattering model.For Cs isotopic chains,the minima of the form factors become flat and gradually disappear.Therefore,it is important to take into account the nuclear deformation during the studies of the electron scattering.The researches in this paper improve the present scattering model and can provide useful guides for further electron scattering experiments.Furthermore,the nuclear cluster structure is studied by the elastic and quasielastic electron scattering.In previous studies,the microscopic nuclear structure models are applied to describe the nuclear cluster structure.To associate the cluster structure with experimental observations,we conduct comparative studies by the combinations of the nuclear structure model and electron scattering theory.Within the framework of the relativistic Hartree-Bogolyubov(RHB),the nuclear density distributions of normal states and cluster states are obtained.With the DWBA and coherent density fluctuation model(CDFM),the nuclear Coulomb form factors and inclusive cross sections of different configurations are calculated.For the elastic electron scattering,there are impressive downward and outward shifts for the diffraction minima of the Coulomb form factors of cluster states,compared with those from the normal states.This due to the differences of nuclear charge radii in r-space.For the quasielastic electron scattering,there are noticeable increases in the peaks of quasielastic scattering and Δ resonance,compared with those from the normal states.In the dip region between the peaks of quasielastic scattering and Δresonance,the value from the cluster state is smaller.These can be attributed to the discrepancies of the Fermi momentum for the cluster configurations in p-space.These studies in this paper illustrate the feasibility of studying the cluster structure by the elastic and quasielastic electron scattering and also provide a new method to study the cluster structure both in the coordinate space and momentum space.