摘要
Within the hadronic transport model IB UU04, we investigate the effect of density-dependent symmetry energy on double neutron/proton （n/p） ratio of free nucleons in heavy ion collisions by taking four isotopic Sn＋Sn reaction systems. Especially the entrance-channel asymmetry and impact-parameter dependence of the effect of symmetry energy are discussed. It is found that in both central and semi-central collisions the sensitivity of the double nip ratio to the density-dependent symmetry energy is more pronounced in neutron-richer systems. Our results also indicate clearly that the effect of symmetry energy is stronger in central collisions than that in semi-central collisions.
Within the hadronic transport model IB UU04, we investigate the effect of density-dependent symmetry energy on double neutron/proton （n/p） ratio of free nucleons in heavy ion collisions by taking four isotopic Sn＋Sn reaction systems. Especially the entrance-channel asymmetry and impact-parameter dependence of the effect of symmetry energy are discussed. It is found that in both central and semi-central collisions the sensitivity of the double nip ratio to the density-dependent symmetry energy is more pronounced in neutron-richer systems. Our results also indicate clearly that the effect of symmetry energy is stronger in central collisions than that in semi-central collisions.
基金
Supported in part by the National Natural Science Foundation of China （10575119）, the Knowledge Innovation Project of Chinese Academy of Sciences （KJCX3-SYW-N2）, the Major State Basic Research Development Programme of China under No 2007CB815004, the CAS/SAFEA International Partnership Programme for Creative Research Teams （CXTD-J2005-1）, and the Asia-Link project （CN/ASIA-LINK/O08（94791）） of the European Commission, We thank Professor B. A. Li for providing the IBUU04 code and for his valuable discussion and suggestion. We also thank Professor M. Di Toro and U. Lombardo for their valuable discussion and suggestion.
