共查询到18条相似文献,搜索用时 203 毫秒
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发展了BUU模型,能够同时研究双中子晕结构核11Li引起反应的核反应总截面和双中子剥去截面,计算中使用软的核物质状态方程和0.8倍的核子–核子碰撞截面,同时还用相对论平均场模型计算的中子和质子密度代替通常使用的方密度分布,计算结果可以很好地拟合不同反应系统的实验数据,假定对于晕核及其核芯核,彼此的核反应总截面与相互作用截面之间的差别相同,那么11Li的双中子剥去截面可以表示成”Li及其核芯核9Li引起反应的核反应总截面之差,研究结果表明这一假定可以适用于高能,对于中能核反应需要更多的实验数据来检验. 相似文献
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将能量和同位旋相关的核子-核子碰撞截面引入QMD模型中,并利用壳模型中简谐振子位的密度分布,抽样出稳定的11Li核.仔细研究了11Li+12C反应的总截面.同Cugnon参数化计算结果进行比较发现,在中低能区,引起反应总截面增大的主要原因是,该能区核子-核子碰撞截面增大、反应时间尺度增长以及Pauli阻塞效应减小. 相似文献
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通过用QMD模型研究晕核11Be+208Pb的近垒熔合反应,发现晕核引起的熔合反应中,并存着两种相互竞争的机制:一方面当入射晕核11Be靠近靶核时,由于11Be是弱束缚体系,与靶核的相互作用可使其很容易破裂或少数核子被靶核俘获形成核子转移反应,从而对于熔合表现出压制;另一方面当11Be的少数中子进入靶核并与靶核相互作用而使得靶核有些激发,而使局部半径增大,导致熔合势垒降低,熔合截面增强.用QMD模型计算出的熔合截面与实验值基本符合,垒附近表现出增强效应. 相似文献
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总结了兰州放射性束实验小组在兰州放射性次级束流线上近几年来利用产生的放射性束流,轰击Si或C等靶子,测量它的反应总截面.并利用经验公式将这些结果归一到相同的能量和靶子,与其相邻的核相比较,发现了9C,11Be,14Be,8B,14B 和12N等核素的反应总截面值有奇异增大的现象.利用微观的Glauber模型进行了计算,对有奇异结构的核采用核芯加价核子的密度分布形式,理论计算和实验结果符合得很好,可以给出奇异核的弥散的密度分布. 相似文献
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GUOWen-Jun JIANGHuan-Qing LIUJian-Ye ZUOWei RENZhong-Zhou LEEXi-Guo 《理论物理通讯》2003,40(5):577-584
We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy.The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite digerent mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections, induced by the halo nuclei due to the very weak binding and the very extended density distribution. 相似文献
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We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable. nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy. The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite different mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections induced by the halo nuclei due to the very weak binding and the very extended density distribution. 相似文献
13.
FAN Guang-Wei XU Wang M.Fukuda PAN Qiang-Yan CAI Xiao-Lu FAN Gong-Tao LI Yong-Jiang LUO Wen XU Ben-Ji YAN Zhe YANG Li-Feng 《中国物理C(英文版)》2010,34(10)
We study the reaction cross sections(σR) and root-mean-square(RMS) radii of 8Li and 8B,the halo-like nuclei,with stable target 12C,27Al and 9Be within the standard optical-limit Glauber model,using densities obtained from relativistic mean-field(RMF) formalisms and other types of distributions.It is found that the experimental σR can be reproduced well at high energy.The RMS radius and △r extracted by RMFtheory and harmonic oscillator distribution are compared.We find that the RMS radius and △r of 8B are larger than those of 8Li.In addition,we analyze in detail the relationship between σR and density distribution. 相似文献
14.
Aumann T Navin A Balamuth DP Bazin D Blank B Brown BA Bush JE Caggiano JA Davids B Glasmacher T Guimaraes V Hansen PG Ibbotson RW Karnes D Kolata JJ Maddalena V Pritychenko B Scheit H Sherrill BM Tostevin JA 《Physical review letters》2000,84(1):35-38
The structure of the halo nucleus 11Be has been studied using the reaction 9Be(11Be,10Be+gamma)X at 60 MeV/nucleon. The ground state structure of 11Be is determined by comparing the experimental cross sections to a calculation combining spectroscopic factors from the shell model with l-dependent single-particle cross sections obtained in an eikonal model. This experiment shows the dominant 1s single-particle character of the 11Be ground state and indicates a small contribution of 0d admixture in the wave function. After correction for the approximately 22% intensity to excited levels, a clean and precise distribution of parallel momentum for knockout from the 1s halo wave function is obtained for the first time. 相似文献
15.
We introduced an extended Glauber theory for a halo nucleus scattering, where the halo nucleons and the nuclear core were treated separately. Expressions of reaction and interaction cross sections of the halo nucleus scattering were derived. We took the halo structure of the projectile nucleus into account and adopted an improved optical limit approximation. In the framework of the extended Glauber theory, we studied the reaction cross section for the halo nucleus 14Be scattering on a target 12C. For comparison, the reaction cross sections of 12Be+12C were calculated as well. The density distribution of target 12C is taken from experiments, and those of the projectiles 12Be and 14Be were obtained by two methods. One is that the harmonic oscillator wave functions for 12Be and 14Be are used. The length of harmonic oscillator is adjusted to reproduce the reaction cross section of 12Be+12C at the high energy E=790MeV/u . The density distribution of 14Be was also calculated self-consistently in the relativistic mean field (RMF) theory, with a long tail wave functions for the two neutrons in 14Be. It was found that the calculated reaction cross sections for 12Be+12C at E=790MeV/u and E=56.5MeV/u were in good agreement with the experimental data no matter harmonic oscillator or RMF wave functions were used. In contrast, the experiments of the reaction cross sections for 14Be+ 12C could only be reproduced when the wave functions of two 2s1/2 neutrons spreaded over with a long tail. It comes to a conclusion that two outside neutrons in 14Be form a halo structure. 相似文献
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D. V. Bolotov O. M. Knyazkov I. N. Kuchtina S. A. Fayans 《Physics of Atomic Nuclei》2000,63(9):1546-1561
The effect of the density dependence of effective nucleon-nucleon forces on the folded potential of the interactions of the light exotic nuclei 6He, 11Li, 11Be, and 8B with the stable nucleus 12C is studied, and the corresponding experimental data on the total reaction cross sections and on elastic scattering are analyzed. A semimicroscopic double-folding model featuring various density-dependent forces based on the M3Y interaction is used together with the nucleon densities as calculated within the density-functional method by using a unified set of parameters for all the above nuclei. It is shown that the angular distributions recently measured for elastic 6He scattering on 12C at an energy of 41.6 MeV per projectile nucleon and for elastic 11Be scattering on 12C at an energy of 49.3 MeV per projectile nucleon can be described satisfactorily if the real part of the optical folded potential is supplemented with a surface term mimicking the contribution of the dynamical polarization potential. 相似文献
17.
We have extracted the nuclear asymptotic normalization coefficients (ANC) for the virtual transitions B→A+N via some transfer reactions and the radioactive nuclear beam experiments. With these coefficients, root-mean-square (rms) radii for the valence particle in some possible halo nuclei have been calculated. The values of rms radii extracted with ANC approach are nearly model-independent, hence are a good quantity for the investigation of nuclear halo. In addition, we have also calculated the rms radii for the two valence neutrons in some three-body systems in terms of the relationship between the radii of valence particle, core nucleus and nuclear matter. With two conditions for nuclear halo formation, we have examined these extracted rms radii. The results show that 11Be(1/2+, g.s), 12B(1-, 2.621 MeV), 13C(1/2+, 3.089 MeV), 14C(0-, 6.903 MeV), 14C(1-, 6.094 MeV), 15C(1/2+, g.s) and 19C(1/2+, g.s) with the valence particle in the 2s ground or excited state are the neutron halo nuclei, whereas 17F(1/2+, 0.495 MeV) and 21Na(1/2+, 2.423 MeV) are the proton halo nuclei in the excited state. For three-body systems, except the well-established two-neutron halo nuclei 6He and 11Li, 14Be and 17B might be the two-neutron halo nuclei as well. 相似文献