Microscopic Study Of Nuclear Low Energy Collective States

The nucleus is a complex multi-particle quantum system.People have not fully understood the interaction and properties of nucleons.Most of the existing nuclear forces are effective phenomenological models,and the model parameters are mostly based on the knowledge of nuclear power and the ground state properties of the atomic nucleus.Therefore,the study of the nature of the nucleus can be used to measure the model and its parameters.Giant resonance is a low-energy collective excitation mode of the nucleus.It can provide a large amount of information on the nuclear structure.The study of nuclear resonance can help people understand the interaction of the nucleus.In this paper,the independent particle model is used,with Skyrme-Hartree-Fock+BCS and quasi-particle random phase approximation method(QRPA)as the theoretical framework.The ground state of isotope chain nuclei of the rich neutrons 58 Ni-84Ni and 104Sn-132Sn,and properties related to 2+and 3-collective giant resonance are calculated using the interactions of SkM*、SGII and SLy5,and Skyrme.And he effect of tensor interaction on the low energy collective excited state of 104Sn-132Sn isotope chain nuclei is compared.First,by comparing with the experimental neutron pair energy gap,the interaction strength of 68Ni and 120Sn neutron pairs was determined,and it was generalized to calculate the properties of other isotope chain nuclei.Secondly,the ground state properties of the nucleus of Ni and Sn isotope chains are calculated and compared with the experimental values.The results show that our calculation results can well describe the ground state properties of the Ni and Sn isotope chains.Next,we conducted specific calculations and analysis of the low-energy excited states of the 2+and 3-states of the two isotope chain nuclei.It was found that the excitation energy of the two isotope chains increased greatly at the magic number.This phenomenon is related to the shell structure of the nucleus.In order to obtain further verification,the composition of the transition configuration of the two excitation modes was analyzed.The results show that,as the number of neutrons increases,the configuration that mainly contributes to the excited state changes from proton-dominated to neutron-dominated and exhibits good collectiveness.In order to obtain more information,the transition densities of selected nuclei of two isotopic chain nuclei were studied,which showed the movement of their internal nuclei when the nuclei were under a certain energy.The transition density verifies the analysis of the transition configuration that neutron transitions begin to show significant advantages as the number of neutrons increases.Finally,although tensor interactions have been neglected by people,studies in recent years have shown that tensor interaction terms are very important for describing the evolution of shells in unstable nuclei,so tensor interactions are introduced in the calculations and studied.It was found that the tensor interaction has a certain effect on the excitation energy of the low-energy excited state of Sn isotope chain nuclei and the transition intensity.