活性靶技术熔合截面测量极限研究  

A Study of the Energy Limit for Measuring Fusion Cross Sections with the Active Target Technique

作　　者：季炼程 张宁涛[1] 林炜平 唐晓东 JI Liancheng;ZHANG Ningtao;LIN Weiping;TANG Xiaodong(Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China)

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]四川大学原子核科学技术研究所,成都610064

出　　处：《原子核物理评论》2018年第2期119-126,共8页Nuclear Physics Review

基　　金：国家重点研发计划项目(2016YFA0400501);国家自然科学基金联合基金项目(U1632142)~~

摘　　要：天体环境中丰中子核素熔合反应率对研究中子星表面超级暴现象的点火机制有重要意义。由于次级束流强过低,无法使用传统固体靶实验技术测量垒下熔合反应截面。活性靶技术的发展为垒下丰中子核素熔合反应截面的测量提供了可行的途径。基于Geant4模拟详细地分析了多重采样电离室(MUSIC)与时间投影室(TPC)两种活性靶探测器中熔合反应与弹性散射的运动学性质,给出了4种熔合反应鉴别判据,并且计算了由这些判据误判引起的熔合截面系统误差。在Ecm=13.6 Me V时,MUSIC与TPC的弹性散射误判截面分别为0.5 mb和2.9×10^(-3)mb,都远小于此时熔合截面(877 mb)。在垒下,MSUIC的熔合截面系统误差已经超出实验测量要求,而TPC能够进行实验测量的能量可以降低至Ecm=4.7 Me V。Reaction rates of fusion reactions among neutron-rich nuclei in the astrophysical environment are of great significance to understand the ignition of superbursts on neutron stars. Since beam intensity is rather low for radioactive ion beams, it is extremely difficult to operate a direct measurement for cross sections of such fusion reactions below the Coulomb barrier using thick target technique. In this case, a novel technique, active target technique, has been developed recently. To study the energy limit for measurement below Coulomb barrier,the kinematics of elastic scattering and fusion reaction in MUSIC and TPC are discussed with Geant4 simulation.Four identification methods are used and uncertainties of cross sections resulted from misjudgments are calculated.With Ecm=13.6 Me V, the uncertainties of cross sections for MUSIC and TPC are 0.5 mb and 2.9×10-3 mb,respectively. The uncertainties for MUSIC become far beyond measurement when below coulomb barrier, while TPC remains to be a suitable detector for measuring fusion cross sections until Ecm=4.7 Me V.

关 键 词：活性靶 熔合反应 弹性散射 GEANT4 丰中子核素 

分 类 号：O571.1[理学—粒子物理与原子核物理]