利用同位旋相关的量子分子动力学(IQMD)模型模拟了4He+208Pb的碰撞反应,发现中子一质子产额比(Rnp)与208Pb的中子皮(σnp)之间存在很好的线性关联,中子一质子产额比可以作为中子皮厚度测量的一个探针。选取IQMD模型中核物质状态方程的两套不同势参数进行模拟,通过对比发现,中子皮的厚度测量探针(中子一质子产额比)对核物质状态方程中选择软势和硬势非常敏感,相同反应条件下,软势比硬势计算所得的中子质子产额比要低。无论选择何种状态方程参数,中子质子产额比与中子皮之间都存在线性关联。
The reaction system of 4He + 208pb has been simulated by Isospin-dependent Quantum Molecu- lar Dynamics (IQMD) mode and it was found that the neutron-to-proton yield ratio (Rnp) has a good linear relationship with the neutron skin thickness of 208pb. Therefore Rnp could be taken as a probe of neutron skin thickness of 208pb. Using two sets of parameters for the nuclear equation of state (EOS) in IQMD model, it shows that Rnp is sensitive to nuclear equation of state. The calculation results of Rnp with the soft EOS is lower than the hard EOS. No matter which kind of EOS parameter has been chosen, however, Rnp holds a good linear correlation with the neutron skin thickness.