基于最近更新的极端相对论量子分子动力学模型,研究了197Au+197Au产生的中子和氢同位素的横动量依赖的椭圆流和轻带电粒子的产额比。发现中子和氢同位素的椭圆流之比vn H2/v2敏感于对称能的高密行为,而3H和3He的产额比敏感于对称能的低密行为。通过比较FOPI/LAND和FOPI合作组的最新实验数据与模型模拟的结果,发现接近线性对称能的Skyrme参数给出的结果能与这两个实验值都符合。
Based on the newly updated version of the Ultra-relativistic quantum molecular dynamics (UrQMD) model, the transverse-momentum dependent elliptic flow ratio of free neutrons vs hydrogen isotopes and the yield ratio of 3H vs 3He clusters emitted from 197Au+197Au collisions at the incident energy 400 MeV/nucleon are studied. It is found that the elliptic flow ratio vn2/vH2 is sensitive to the symmetry energy at supra-saturation densities, while the yield ratio 3 H/3 He is sensitive to the nuclear symmetry energy at sub-saturation densities. By comparing the data from FOPI/LAND and FOPI Collaborations with model calculations using various Skyrme interactions (all exhibiting similar values of isoscalar incompressibility but very different density dependences of the symmetry energy), we find that results using Skyrme interactions which parameterize a moderately soft to linear symmetry energy can reproduce both data quite well.