Research On Exotic Nuclei With Relativistic Mean-field Theory

At first, we introduce in detail relativistic mean-field (RMF) theory, where a common Lagrangian density is presented. Starting with this Lagrangian density, we can obtain the Dirac equation and Klein-Gordon equations for nucleon and meson field by using Euler-Lagrangian equation. Next we discuss the application of the RMF theory for the spherical and the axially symmetric deformed nuclei.For the spherical shape nuclei, we mainly study the phenomenon of halo. Halo is very common. The main characters of halo are that the valence nucleons are weekly bound and there are large matter root-mean-square radii of nuclei. The necessary conditions of the formation of halo are: weekly bound, low orbit angular momentum and short distance interaction. Halos can appear in both the ground states of the nuclei far from β-stability line and the excited states of the steady nuclei. The RMF theorycan reproduce the halos, observed in experiment and predict some halo nuclei. For halos in the ground states, 28S and 45S are choused as examples, two-proton halo in 28S and one-neutron halo in 45S are suggested. For halos in the excited states, we choose 17O, 17F, 69Ni and 70Ni as examples, one-neutron halo in 17O and one-proton halo in 17F are suggested in their first excited states. For 69,70Ni, halo structures are suggestedin both the first excited states and the second excited states of 69,70Ni.For the deformed nuclei, we study the nuclear ground state properties in light nuclei region by using the deformed RMF theory. The calculated binding energies are in good agreement with experimental data. We also point out the localities of the single-neutron drip-line and the double-neutron drip-line nuclei. In the end, we study the critical point nuclei in the rare-earth region with relativistic mean field theory, the critical point nuclei are suggested to be 148Nd and 150Nd for Nd isotopes, while 148Nd is the best candidate and 150Nd is slightly to the rotor side of the phase transition. For Gd and Dy isotopes, the critical point nuclei are suggested to be 150,152Gd and 152,154Dy respectively.