Probing the density dependence of the symmetry energy with central heavy ion collisions  

作　　者：XIE Wenjie ZHANG Fengshou 

机构地区：[1]The Key Laboratory of Beam Technology and Material Modification of Ministry of Education,College of Nuclear Science and Technology,Beijing Normal University [2]Beijing Radiation Center [3]Department of Physics,Yuncheng University [4]Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Accelerator of Lanzhou

出　　处：《Nuclear Science and Techniques》2013年第5期7-12,共6页核技术（英文）

基　　金：Supported by National Natural Science Foundation of China(NSFC) projects (Nos.11025524 and 11161130520);National Basic Research Program of China(No.2010CB832903)

摘　　要：An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.By taking several forms of nuclear symmetry energy,we calculate the time evolutions of neutron over proton ratio,π multiplicity and π-/π+ ratio,and the kinetic energy and transverse momentum spectra of π-/π+ ratio in the heavy ion collisions at 400A MeV.It is found that the neutron over proton ratio and π-/π+ ratio are very sensitive to the nuclear symmetry energy,and the π-is more sensitive to the nuclear symmetry energy than the π+.A supersoft symmetry energy results in a larger π-/π+ ratio.An improved isospin dependent Boltzmann Langevin model, in which the inelastic channels and momentum dependent interactions are incorporated, is used to investigate the high-density behavior of nuclear symmetry energy. By taking several forms of nuclear symmetry energy, we calculate the time evolutions of neutron over proton ratio, π ultiplicity and π-/π＋ ratio, and the kinetic energy and transverse momentum spectra of π-/π＋ ratio in the heavy ion collisions at 400A MeV. It is found that the neutron over proton ratio and π-/π＋ ratio are very sensitive to the nuclear symmetry energy, and the π- is more sensitive to the nuclear symmetry energy than the π＋. A supersoft symmetry energy results in a larger π-/π＋ ratio.

关 键 词：重离子碰撞 对称能 BOLTZMANN 中央 密度 探测 同位旋相关 相互作用 

分 类 号：O571.6[理学—粒子物理与原子核物理] O572[理学—物理]