Research On The Stiffness Of Nucleus And Influence Of Nuclear Deformation On The Structure Of Diving Potential

In recent years, the synthesis of superheavy nuclei（SHN） has became an important field in nuclear physics. Great achievements have been obtained in both experimental aspect and theoretical aspect. Because of the difficulties for synthesizing SHN experimentally, it is important to study the mechanism for the heavy-ion reactions theoretically. Thus, some problems related to the nuclear heavy-ion reaction mechanism are investigated in this work.In the first part, the nuclear energy as a function of the deformation（potential energy surface, PES） for Ca, Fe and Pb isotopes are studied within the framework of relativistic mean field（RMF） theory. The stiffness for the nucleus is then taken from the PES. It is shown that the stiffness for the nucleus with magic number is much larger than that for the nucleus away from magic number. The stiffness from RMF is also compared with that from liquid drop model. The single particle energy levels for protons and neutrons are also calculated with RMF theory and the shell correction energies for the nucleus at ground state and away from ground state are calculated. It is found that the shell correction energy contributes to main part of the stiffness of nucleus.In the second part, the nucleus-nucleus potentials between⁴0-50Ca+²¹³Pb systems are calculated within the framework of the di-nuclear system model. It is found that the nucleus-nucleus potentials with octupole deformations are lower than the potentials without octupole deformations. The quasi-fission barrier and the pocket of the nucleus-nucleus potential become deeper as the neutron number increases. The influence of deformation and stiffness parameter on the intrinsic energy are also studied. The ‘pocket’ of intrinsic energy with the stiffness parameter calculated from Liquid Drop Model and RMF theory becomes shallower and remains almost the same,respectively, as the quadrupole deformation increases. Then the influence of theoctupole deformation on the driving potential for two systems(⁴8Ca+²⁰⁸Pb and⁶0Fe+²²⁴Ra) are studied. The octupole deformation slightly enlarge the inner fusion barrier of the di-nuclear system at belly-belly orientation. But at tip-tip orientation, the inner fusion barriers of ⁴8Ca+²⁰⁸Pb and ⁶0Fe+²²⁴Ra decrease and increase significantly,respectively.