中能重离子碰撞中带电粒子多重性的同位旋效应  

Isospin Effect of Charged Particle Multiplicity in Intermediate Energy Heavy Ion Collisions

作　　者：胡荣江[1] 吴和宇[1] 靳根明[1] 诸永泰[1] 李松林[1] 肖志刚[1] 王宏伟[1] 段利敏[1] 李祖玉[1] 殷旭[1] 王素芳[1] 张保国[1] 魏志勇[1] 王晓秋[1] 卢朝晖[1] 朱海东[1] 冯兆庆[1] 袁小华[1] 

机构地区：[1]中国科学院近代物理研究所

出　　处：《高能物理与核物理》2003年第11期990-994,共5页High Energy Physics and Nuclear Physics

基　　金：国家自然科学基金(10175081;19575055);国家重点基础研究发展规划项目(G2000077401)~~

摘　　要：利用兰州4π带电粒子探测器阵列测量带电粒子多重性,研究了55MeV/u ^(40)Ar+^(58,64)Ni核反应中He和中等质量碎片的产额与反应系统同位旋的关系,以及这种同位旋效应与反应系统的碰撞参数(即碰撞的激烈程度)、系统的激发能的变化关系,对两个反应系统,观察到带电粒子多重性中He的比分随带电粒子多重性的增加而增大,带电粒子多重性中IMF的比分随带电粒子多重性的增加而先增大,后减小的规律.两个反应系统虽然具有相同的核电荷数,但轻粒子He和中等质量碎片在多重性中的比分有明显的同位旋相关性。The dependence of He and intermediate mass fragments (IMF) production rates in the reactions 55MeV/u Ar + 58.64 Ni on the isospin, impact parameter and primary excitation energy of the reaction system was studied by using the 4:v charged particle multidetector array system ( MUDAL) . For the mentioned two reaction systems, the measured He particle contribution in the total charged particle multiplicity increases with increasing the total charged particle multiplicity but for the contribution of IMFs in the total charged particle multiplicity increases with increasing the total charged particle multiplicity at lower total charged particle multiplicities, and latter on it drops down with further increaseg of the total charged particle multiplicities. The experimental results of these two reaction systems with the same nuclear charge indicate that the contributions of He and IMFs in the total charged particle multiplicities are obviously isospin dependent.

关 键 词：中能重离子碰撞 带电粒子 多重性 重离子物理 同位旋效应 激发能 碰撞参数 

分 类 号：O572.2[理学—粒子物理与原子核物理]