Isospin Effects In Breakup Reaction Induced By Deuteron

The nuclear symmetry energy is the energy related to neutron-proton isospin asymmetry in the nuclear matter. Its density dependence is not only very important to the structure and the reaction of the nuclear far away from the β-stability line, but al-so has great effects on many issue in astrophysics. With great effort in last two decades, the significant progress made in constraining the nuclear symmetry energy, but there is still large uncertainty in the density dependence of symmetry energy.As shown in our previous work, due to the isovector potential, there is a significant difference in the scattering angle between proton-and neutron-induced scattering off a heavy target at a large impact parameter. Since it is hard to get a monochromatic neutron beam at around 100 MeV, the experimental test remains a difficult task. In this thesis, by using an improved quantum molecular dynamics (ImQMD) model, we made some the investigations on the isospin effects in polarized deuteron scattering off the heavy target, and tried to find the probe which is sensitive to the density dependence of symmetry energy and weakly depend on the model.Firstly, the reactions of polarized deuteron, which longitudinal symmetric axis is on the beam direction, bombarding on 124Sn with 100 MeV/u were studied. It was found that the distributions of elastic scattering angle of proton and neutron originating from the breakup deuteron are very similar to the results of the individual proton- and neutron-induced case. Thus, the polarized deuteron scatting off heavy ion can be an alternative to the individual proton- and neutron-induced reaction. It was also found that, the sensitivity of scattering angle on the symmetry energy becomes weaker with impact parameter decrease, due to the enhancement of isoscaler potential and Coulom-b potential. In addition, the cross section, which is obtained by mixing the results in impact parameter window for peripheral collisions, also loses its sensitivity on the symmetry energy. To solve this problem, we promoted a new probe namely the dif-ference between scattering angle of proton and neutron originating from the breakup deuteron. This probe is very sensitive to the symmetry energy but unsensitive to the impact parameter, so it can be a promising probe to constraint the symmetry energy at subsaturation density.