相对论重离子碰撞中的线性背景与非线性效应

Linear Background and Nonlinear Effect in Relativistic Heavy Ion Collisions

系统分析了ｐ－Ａ，１６Ｏ－Ａ和３２Ｓ－Ａ过程快度分布的靶核依赖性．指出：将核子－核，核－核碰撞看成核子－核子碰撞的线性叠加的几何模型只能得到靶核指数α（η） ０．４．靶核碎裂区α（η）→１的实验数据表明，目前能量下的高能重离子碰撞中，非线性效应已不可忽略．流体动力学模型计算的结果能很好地描述不同射弹过程的靶核依赖性．

The target mass dependence, α,on the yield of charged particles as a function of pseudorapidity n has been investigated for p, 16O and 32S induced central collisions at 200A GeV. It is pointed out that α(η) ≤ 0.4 if we only consider the simple linear superposition of nucleon-nucleon collisions. The experimental data α→1 in the target fragmentation region show the importance of nonlinear collective effect even at present incident energy. Our results from a hydrodynamical model can describe the target mlass dependence well for different projectiles in the whole rapidity ragion.