400 A MeV 12 C诱发乳胶核反应重电离粒子前后关联研究

Abstract

对400 AMeV 12C诱发乳胶核反应重电离粒子的前后关联进行了研究。重电离粒子来源于靶核碎片，分为灰径迹粒子和黑径迹粒子两种。实验结果很好地验证了核-核碰撞几何模型。灰径迹粒子的发射在前、后半球是各向异性的，而黑径迹粒子的发射基本是一致的。向前、向后发射的灰径迹粒子、黑径迹粒子平均多重数对重电离粒子数nh呈线性依赖，黑径迹粒子、灰径迹粒子的向前发射随nh的增加而增加的幅度分别大于其向后发射随nh的增加而增加的幅度，但核内级联效应受靶核大小的影响，向后半球内发射的灰径迹粒子平均多重数随nh的增加有饱和现象，这些多重数关联特性基本上可以利用基于碰撞几何的旁观体-反应体模型及级联蒸发模型来解释。 The forward-backward multiplicity correlation of heavily ionized particles produced in 12C-emulsion interactions at 400 AMeV is investigated. The heavy ionized particles, come from the target fragments, are divided into grey track particle and black track particle. The experimental results can be well explained by the geometry model of the nucleus-nucleus collisions. The emission of grey track particles in forward and backward hemisphere is not isotropic, but the emission of black track particle is almost isotropic. The averaged multiplicity of grey track particles and black track particles in forward and backward hemisphere linearly depend on the number of heavily ionized particle nh, the correlation strength in forward hemisphere is greater than that in backward hemisphere, but the dependence of grey track particle in backward hemisphere on the number of heavily ionized particle nh shows the saturation because of the intranuclar cascade effect is influenced by target size. The characteristics of multiplicity correlations can be well explained by the participant-spectator model based on the colliding geometrical picture and the cascade evaporation model of high energy nucleus-nucleus collisions.