同位旋相关量探测重离子碰撞趋平衡及对称能

用IQMD模型分析了由⁹⁶Ru和⁹⁶Zr构成的质量对称、同位旋不对称的一组中能核反应,寻求对对称势强度的敏感量和研究反应最终是否达到平衡的问题.研究表明中子-质子差快度分布在弹或靶快度区对对称势强度敏感,且越丰中子的核系统越敏感.中子-质子差快度分布还表明能量为400MeV/u时达到的平衡程度要比100MeV/u时的高.出射的核子、轻带电粒子和中等质量碎片的N/Z显示IMF的出射有记忆效应.随着入射能量由100MeV/u增加到400MeV/u,IMF的N/Z有明显下降,这是由于随入射能量增加使IMF中同位素的分布发生变化所致.

Probing Equilibration in HICs and Symmetry Energy by Using Isospin-Related Observables

We have studied the equilibration with respect to isospin degree of freedom in four systems 96 Ru+ 96 Ru, 96 Ru+ 96 Zr, 96 Zr+ 96 Ru, 96 Zr+ 96 Zr at 100 MeV/u and 400MeV/u with isospin dependent QMD. It is proposed in this paper that the neutron proton differential rapidity distribution is a sensitive probe to the degree of equilibration with respect to the isospin degree of freedom. By analyzing the average N/Z ratio of emitted nucleons, light charged particles (LCP) and intermediate mass fragments (IMF), it is found that there exists memory effect in multifragmentation process. The average N/Z ratio of IMF reduces largely as beam energy increases from 100MeV/u to 400MeV/u, which may result from the change of the behavior of the isotope distribution of IMF. The isotope distribution of IMF does also show certain memory effect at 100 MeV/u case but not at 400 MeV/u case. We also found the rapidity distribution of differential neutron proton counting in neutron rich nucleus nucleus collisions at intermediate energies is sensitive to the isospin dependent part of nuclear potential. In conclusion, based on these studies we have found it's an effective way to explore whether the final equilibration could be reached in intermediate HICs by constructing a set of isospin (a)symmetry nuclear nuclear collision systems with same mass and different charge.