Effect of Isospin Dependence of Nucleon-nucleon Cross Section on Isospin Fractionation Ratio as Increase of Neutron-proton Ratio of Collision System  

作　　者：Liu Jianye, Guo Wenyun, Ren Zbongzhou, Zuo Wei and Li Xiguo 

出　　处：《近代物理研究所和兰州重离子加速器实验室年报：英文版》2005年第1期12-12,共1页IMP & HIRFL Annual Report

摘　　要：Effect of isospin dependence of nucleon-nucleon (N-N) cross sectionσNNiso on the isospin fractionation ratio (n/p)free/(n/p)liq as the increase of neutron-proton ratio of collision system (n/p)sys is investigated in heavy ion collisions. Where the isospin independent N-N cross sectionsσ1noiso andσ2noiso are defined asσnn=σpp =σnp(σ1noiso) andσnn=σpp=(1/2) (σnp+σnn)(σ2noiso) respectively. An empirical density dependent expression of the in-medium N-N cross sectionEffect of isospin dependence of nucleon-nucleon （N-N） cross sectionσNNiso on the isospin fractionation ratio （n/p）free/（n/p）liq as the increase of neutron-proton ratio of collision system （n/p）sys is investigated in heavy ion collisions. Where the isospin independent N-N cross sectionsσ1noiso andσ2noiso are defined asσnn=σpp =σnp（σ1noiso） andσnn=σpp=（1/2） （σnp＋σnn）（σ2noiso） respectively.

关 键 词：核子碰撞截面 同位旋分馏 同位旋依赖性 碰撞系统 质子 中子 神经网络 重离子碰撞 

分 类 号：O571[理学—粒子物理与原子核物理]