CAS OpenIR  > 中科院上海应用物理研究所2004-2010年
Alternative TitleMeasurement of Reaction Cross Section for 25Si and Momentum Distribution for the Fragment and Simulation of Collective Flow for Light Fragments at Intermediate Energy
Thesis Advisor马余刚
Degree Grantor中国科学院上海应用物理研究所
Place of Conferral上海应用物理研究所
Keyword放射性核束物理 核反应截面 碎片动量分布 量子分子动力学模型 集体流 椭圆流核子数标度律
Abstract本论文较系统的介绍了放射性核束物理中奇异核的研究方法和中能重离子碰撞中集体流性质的研究。主要内容包括:介绍了奇异核研究的理论和实验方法;介绍了在日本理化学研究所(RIKEN)完成的实验和本人承担的部分数据分析工作;用同位旋相关的量子分子动力学(IQMD)模型研究中能重离子碰撞中轻碎片的集体流性质等。 11Li、11Be等中子晕核的发现,使得利用放射性次级束来研究远离稳定线核的结构成为当前核物理研究中的重要前沿之一。核反应总截面¾R和碎裂产物平行动量分布是描述原子核反应基本特征的很重要的物理量,从中可以得到有关核反应、核结构和核内核子分布的信息,同时它也是现有奇异核束流条件下少数几个易于测量的物理量。故此,我们较系统的介绍了奇异核反应研究的实验方法,以及一些可以用于奇异核结构和反应的理论模型。 我们利用一种新的实验方法-透射输运法,同时进行了核反应截面和碎裂产物动量分布的实验测量。基于透射输运法,我们于2004年在日本理化所RIPS 放射性束流装置上测量了能量约为70A MeV 的23Al 及其邻近核(N = 10、11)的反应截面及其相应的碎裂反应产物的平行动量分布。通过综合分析这些核的反应截面和碎裂产物动量分布宽度的变化趋势,可以研究23Al及其邻近核是否存在质子晕或皮结构。本论文中主要介绍了25Si核的反应截面和其碎片24Al的平行动量分布的分析结果,推断25Si可能存在质子皮结构。 我们利用IQMD模型来研究中能重离子碰撞中轻碎片的集体流性质。发现了横向动量依赖的椭圆流存在核子数标度律现象;发现不同轻碎片的比值v4/v22保持一个常数0.5,既不依赖于横向动量,也不依赖于快度;发现动量空间密度的幂指数律在中低能区仍然成立;发现快度依赖的各向异性流可以用一个质量数A相关的一次函数C(A)来标度,等等。我们建议进行相关的实验研究。
Other AbstractIn this thesis the study of the exotic nuclei in radioactive nuclei beam physics field and the study of the collective flows in heavy ion collisions will be introduced systematically. It includes: the introduction about the theoretical and experimental approaches which are used to study the exotic nuclei; the experiment performed at RIKEN Japan, and the data analysis I did; the study of the collective flows for light fragments in heavy ion collisions with Isospin-dependent Quantum Molecular Dynamics (IQMD) model, and so on. Since the discovery of neutron halo nuclei such as 11Li, 11Be etc., study on the structure of nuclei far from the β- stability line becomes one of the central issues of nuclear physics. Reaction cross section σR and parallel momentum distribution are very important quantities characterizing the properties of nuclear reaction. They are also very useful for extracting fundamental information about the nuclear reaction, the nuclear structure and the nucleon density distribution in nucleus, and they are the several measurements that can be measured easily in the condition of the experiment facilities nowadays. So, we introduce systematically the experimental methods which are used to study the exotic nuclei reaction, as well as some theoretical models which can be used to study the exotic nuclei structure and reaction. We used a new transmission-type method, which can be used to measure reaction cross section and longitudinal momentum distribution simultaneously. Based on this experimental method, reaction cross section σR of 23Al and longitudinal momentum distribution p// of 22Mg at the energy near 70A MeV as well as their neighbor nuclei (N = 10, 11) are measured at RIKEN-RIPS in 2004. It can be used to study the possible proton halo or skin structure in 23Al and its neighbors. The results of data analysis for 25Si reaction cross section and its fragment 24Al longitudinal momentum distribution are reported in this thesis, and it is deduced that there may be proton skin structure in 25Si. The collective flows of light fragments in heavy ion collisions are studied by IQMD model. It is found that: there exists a scaling on the nucleon number of light fragments for transverse momentum dependent elliptic flow; the ratios v4/v22 for different light fragments neither depend on transverse momentum nor on rapidity, and keep a constant 0.5; the power law for momentum space densities can also hold in intermediate energy heavy ion collisions; the rapidity dependent anisotropic flows can be scaled by a function C(A) which is linear with fragment mass number A, and so on. We suggest some experiments may be done for these interesting phenomena.
Document Type学位论文
Recommended Citation
GB/T 7714
颜廷志. 25Si的反应截面及其碎片动量分布测量以及中能轻碎片的集体流性质研究[D]. 上海应用物理研究所. 中国科学院上海应用物理研究所,2008.
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