从晕中子核引起核反应中提取对称势

Probing the Symmetrical Potential in Nuclear Reaction Iinduced by Neutron-Halo Nuclei

利用同位旋相关量子分子动力学理论研究了中子晕核引起核反应机制中重要的同位旋效应以提取对称势．因为同位旋相关量子分子动力学理论中的相互作用和介质中核子-核子碰撞截面都灵敏地依赖于碰撞系统的密度分布,本项研究工作基于中子晕核扩展的密度分布．该密度分布包含了反应机制中同位旋效应和疏散内部结构的平均特征．为了弄清楚晕核引起核反应机制的同位旋效应,在完全相同的入射道条件下,比较了由中子晕核炮弹引起的同位旋效应和由相等质量的稳定核炮弹引起同位旋效应．结果发现中子晕核炮弹引起的发射中子-质子比和同位旋分馏比明显大于相等质量稳定弹核产生的结果．因而可以通过理论结果与实验数据的系统比较提取对称势．

In terms of the isospin-dependent quantum molecular dynamics model （IQMD）, important isospin effect in the halo-neutron nucleus induced reaction mechanism is investigated, and consequently, the symmetrical potential form is extracted in the intermediate energy heavy ion collision. Because the interactive potential and in-medium nucleon-nucleon （N-N） cross section in the IQMD model sensitively depend on the density distribution of the colliding system, this type of study is much more based on the extended density distribution with a looser inner nuclear structure of the halo-neutron nucleus. Such a density distribution includes averaged characteristics of the isospin effect of the reaction mechanism and the looser inner nuclear structure. In order to understand clearly the isospin effect of the halo-neutron nucleus induced reaction mechanism, the effects caused by the neutron-halo nucleus and by the stable nucleus with the same mass are compared under the same condition of the incident channel. It is found that in the concerned beam energy region, the ratio of the emitted neutrons and protons and the ratio of the isospin fractionations in the neutron-halo nucleus case are considerably larger than those in the stable nucleus case. Therefore, the information of the symmetry potential in the heavy ion collision can be extracted through such a procedure.