基于双粒子方位角关联方法研究费米能区重离子碰撞中横向流的入射能量依赖关系  

Study of Transverse Flow Dependence on Incident Energy in Heavy-ion Collisions near the Fermi Energy Based on Two-particle Azimuthal Correlation Approach

作　　者：冷强钟 黄宇[1] 张鑫[1] 刘星泉 和田良一 林炜平 郑华[3] 王建松 陈志强[5] 黄美容 任培培 曲国峰 韩纪锋 杨振雷 田国玉 韩瑞[5] 胡强[5] LENG Qiangzhong;HUANG Yu;ZHANG Xin;LIU Xingquan;Wada Ryoichi;LIN Weiping;ZHENG Hua;WANG Jiansong;CHEN Zhiqiang;HUANG Meirong;REN Peipei;QU Guofeng;HAN Jifeng;YANG Zhenlei;TIAN Guoyu;HAN Rui;HU Qiang(Key Laboratory of Radiation Physics and Technology of the Ministry of Education,Institute of Nuclear Science and Technology,Sichuan University,Chengdu 610064,China;Cyclotron Institute,Texas A&M University,College Station,Texas 77843,USA;School of Physics and Information Technology,Shaanxi Normal University,Xi’an 710119,China;School of Science,Huzhou University,Huzhou 313000,Zhejiang,China;Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;College of Physics and Electronics Information,Inner Mongolia University for Nationalities,Tongliao 028000,Inner Mongolia,China;Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China)

机构地区：[1]四川大学原子核科学技术研究所,辐射物理及技术教育部重点实验室,成都610064 [2]Cyclotron Institute,Texas A&M University,College Station,Texas 77843,USA [3]陕西师范大学物理学与信息技术学院,西安710119 [4]湖州师范学院理学院,浙江湖州313000 [5]中国科学院近代物理研究所,兰州730000 [6]内蒙古民族大学物理与电子信息学院,内蒙古通辽028000 [7]中国核动力研究设计院核反应堆系统设计技术重点实验室,成都610213

出　　处：《原子核物理评论》2023年第1期10-16,共7页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(12275186);中央高校基本科研业务费专项资金资助项目(YJ201954,YJ201820)。

摘　　要：基于双粒子方位角关联(2pAC)方法开展了费米能区^(64)Zn轰击^(58)Ni靶的重离子碰撞中横向流入射能量依赖的实验研究。利用考虑了单个事件中参考粒子对剩余体系反冲修正的改进的2pAC方法和已有的2pAC方法分别抽取了26,35和47 MeV/u能量下^(64)Zn+^(58)Ni半中心碰撞的相对横向流强度,发现横向流的强度随入射能量增加而减弱的趋势与抽取横向流过程中是否考虑反冲修正无关,但考虑反冲修正时得到的横向流相对强度对比未考虑反冲修正时显著减小。通过线性拟合得到的相对横向流强度-入射能量关系,进一步获得了^(64)Zn+^(58)Ni半中心碰撞的平衡能分别为(110.1±5.8)MeV/u(改进的2pAC方法)和(128.0±5.6)MeV/u(已有的2pAC方法)。对比以往基于常规反应平面重建方法抽取得到的结果发现,基于改进的2pAC方法得到的结果与以往基于常规方法测得的平衡能-碰撞参数关系符合很好;相反,基于已有2pAC方法得到的结果被显著高估。对比结果证明了在利用2pAC方法抽取横向流强度的过程中考虑反冲修正的必要性,以及在平衡能研究中采用改进的2pAC方法与依赖于反应平面重建的常规方法的等价性。In this article,the incident energy dependence of transverse flow from the collisions of ^(64)Zn+^(58)Ni near the Fermi energy is investigated experimentally based on a two-particle azimuthal correlation(2pAC)approach.The transverse flow values from the mid-peripheral collisions at the incident energies of 26,35 and 47 MeV/u are extracted using the 2pAC approaches with and without the specific consideration of the recoil effect from the emitted particle of interest to the residue in an event-by-event basis,respectively.The flow values extracted from both approaches show consistently increasing trend as a function of incident energy.In contrast,the flow values for the three energies show different in magnitude,that those from the improved 2pAC approach with the consideration of the recoil effect are significantly reduced.The balance energy of the mid-peripheral ^(64)Zn+^(58)Ni collisions is further investigated using linear fit for the obtained transverse flow versus incident energy,and two balance energy values are obtained to be(110.1±5.8)MeV/u for the improved 2pAC approach and(128.0±5.6)MeV/u for the original 2pAC approach,respectively.These two values are compared with those previously measured based on the conventional flow extraction approach involving the reaction plane reconstruction process.It is found that the balance energy from the improved 2pAC approach,rather than that from the original 2pAC approach,follows well the relation of balance energy versus impact parameter from the conventional approach.This comparison suggests the necessity for considering the recoil effect correction in the flow extraction using the 2pAC approach,and the equivalence between the improved 2pAC approach and the conventional flow extraction approach involving the reaction plane reconstruction process in the investigation on the balance energy.

关 键 词：横向流的入射能量依赖 费米能区重离子碰撞 双粒子方位角关联方法 平衡能 

分 类 号：O571.53[理学—粒子物理与原子核物理]