Vorticity Strength And Diproton Emission Of Near Drip-line Nuclei And Threshold Behavior Of Weakly Bound Nuclei

The research of nuclei far fromβ-line is an important topic of nuclear physics. With the developing of experimental technology and the usage of radioactive ion beam, the research of exotic nuclei has been popular. In this paper, we present the two works of drip-line nucleus structure and a work of weakly-bounded nucleus reaction.At present there are contrary conclusion about the threshold anomaly of optical poten-tial for 9Be+208Pb and 209Bi systems in literature. In order to solve this problem, we have precisely re-measured the elastic scattering angular distributions for these two systems to study the unusual optical potential following my master thesis. The parameters of the opti-cal model potential are re-extracted by means of a phenomenological optical model analysis. It shows an unusual potential behavior like the Keeley's prediction and is consistent with the result of our previous experiment.For the neutron-rich nuclei near neutron drip-line, it was predicted by HF+CRPA cal-culation that a considerable amount of transition strength appears just above the neutron threshold. The feature of those transition is that the distribution of the transition density and transition current are spatially extended and the vorticity strength of transition current has a enhancement. By adopting a finite square-well potential, the analytic expressions of transi-tion strengths and the vorticity strengths are derived. It is shown that though the transition strength and the vorticity strength of transition current are independent, both of them appear peaks just above the neutron threshold and mainly come from the neutron orbits with small binding energy. The vorticity strength of low-lying 2+ excited states are usually larger than the 2+ excited states of giant resonance, the possible reason of which has been also discussed in this paper.Finally, We choose the drip-line nucleus 18Ne as an object for researching of two-proton radioactivity. In experiment, the Italy and our groups have done some research about the two-proton radioactivity, and got the excitation-energy spectrum of 18Ne and momentum correlations and the relative angle of the emitted proton pairs. The approach of Monte Carlo simulations is used. In theory, we solve the Lippmann-Schwinger equation of two-nucleon by matrix inversion and get the T matrix of two-body interaction. Then, we consider the 18Ne to be a three-body system of two protons and an 16O core and solve the three-body Faddeev equation by the same approach using the two-body T matrix. We calculate the excitation-energy spectrum of 18Ne and momentum correlations of the emitted proton pairs and find similar results compared with the experiment. A new approach for solving the problem of halo-nuclei has been found.