中子分布弥散度对反应总截面的影响

在引入库仑场修正的Glauber模型基础上,区分入射弹核和靶核中的中子、质子,并考虑有限力程相互作用,发展了一个计算核反应总截面的微观修正模型.如果引入一个核内中子分布弥散度随中子分离能的变化关系,则能较好地解释奇异核(如⁸He,¹¹Li,¹¹Be)反应总截面的反常增加.同时,该修正模型还能在低能到高能的范围内较好地拟会稳定核的反应总截面.     

S+W中心碰撞的奇异粒子产生

用相对论核－核碰撞的事例产生器──LUCIAE产生和分析了200A GeV S＋W中心碰撞中的奇异介子K0s、奇异重子A和A,给出了它们的产额对横质量的分布及奇异介子对有异重子的产生比,并与实验数据进行了比较.     

奇异值非线性修正的低对比度红外图像实时增强

由于场景中目标与背景的温差相对较小,红外图像会存在对比度低、视觉效果差的问题,针对这一问题,提出一种基于奇异值非线性修正的红外图像对比度实时增强方法。该方法首先对红外图像进行奇异值分解得到其原始奇异值,然后采用一个对数型非线性变换对图像奇异值进行优化,最后根据修正的奇异值重构出对比度增强的红外图像。利用对数型非线性变换修正图像奇异值不仅能够有效拉伸奇异值的动态范围,同时可优化奇异值的变化梯度,使图像的能量信息得到更充分地表达,改善红外图像不良的视觉效果。实验结果表明,该方法较几种对比方法在视觉效果和客观评价方面均具有更优的增强性能;同时体现出良好的实时性,为实现红外图像的实时增强提供了新途径。     

对脉冲近似运动学修正的研究

本文讨论了对脉冲近似进行总能量守恒运动学修正所带来的影响, 指出此运动学修正对解释轻子核子深部非弹散射和轻子原子核深部非弹散射中的奇异现象都起着很重要的作用. 由此可解释Bjorken标度不变性破坏现象及EMC效应.     

三维声场边界元法几乎奇异积分问题分析

以三维声场问题为例,提出一种准确计算高阶单元几乎奇异积分的半解析算法.首先分析高阶单元几何特征,构造近似几何量,然后应用扣除法,将奇异积分核函数分解为规则核函数与近似几何量表达的奇异核函数.规则核函数积分采用常规Gauss数值积分计算,奇异核函数积分采用半解析算法计算.给出三维声场内问题和外问题经典算例,计算了近边界点的声压,结果证明本文半解析算法的有效性和准确性.     

基于积分方程法和奇异值分解的磁性目标磁场延拓技术研究

对磁性目标磁场延拓技术进行了研究,提出了一种基于积分方程法和奇异值分解的新方法.应用该方法只需要采用积分方程法对磁性目标的结构进行较为粗略的单元划分,利用目标下方大平面上的磁场测量值,得到相应的线性方程组.采用基于奇异值分解的截断奇异值方法和修正奇异值方法对该线性方程组进行正则化求解,可实现磁性目标磁场的三维磁场重建、向上或向下延拓.该方法较以前的方法,提高了磁性目标磁场延拓的精度和可靠性,并且解决了磁性目标磁场在一定范围内向上延拓的技术难题. 关键词： 磁性目标磁场 延拓 积分方程法 奇异值分解     

相对论和非相对论理论模型研究奇异核的性质

采用相对论和非相对论理论模型可描述奇异核的性质 .相对论平均场理论预言了2 6,2 7,2 8P存在一个质子晕 ,而27,28,29S存在两个质子晕 .最近 ,MSU的最新的实验发现了2 6,2 7,2 8P核存在一个质子晕.采用相对论 Hartree- Fock理论研究了 Fock项和矢量介子对奇异核性质的贡献,研究表明交换项和矢量介子对非常丰中子核性质的影响非常不同于对稳定线附近核性质的影响.同时,采用形变的Hartree- Fock- Bogoliubov理论研究了某些轻核同位素链的性质和形变.     

200AGeVpp、pS和SS碰撞中单奇异粒子产生数据的分析

用相对论性核-核碰撞的蒙特卡罗事件产生器──LUCIAE,分析了200AGeVpp､pS和SS碰撞中单奇异粒子产生的实验数据.结果表明:SS中心碰撞相对于pp或pS最小偏畸事件,似乎有更强的末态相互作用,更短的奇异粒子产生时间,和更大的奇异粒子对压低因子. 从pp到pS再到SS奇异增强的实验事实,似乎不必引入夸克-胶子等离子体就能得到解释.     

奇异核的实验研究

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.     

超核的相对论平均场计算

利用相对论平均场方法计算了奇异、粲和底超核的部分性质,包括各种不同味的超核的单粒子能量以及其他一些静态性质,并对结果进行了比较.对各种味的重子的势阱深度和耦合常数做了估计,得到丰富的结果.建议寻找质量数大于10?0的粲超核.同时探讨了不同重子杂质对原子核芯性质的可能影响.     

Scaling property in one-nucleon removal reactions induced by exotic nuclei

Assuming a core plus valence nucleon structure, one-nucleon removal reaction is investigated within the framework of few-body Glauber theory. Fermi-type distribution is used for the core density, while the wavefunction of the valence nucleon is calculated by solving the single particle eigeuvalue problem of the SchrSdinger equation with the Woods-Saxon potential. The parallel momentum distribution (P//) of the fragments is calculated for isotopes with 3 < Z < 18. A remarkable scaling property is observed from the dependence of the dimensionless quantity R2v/R2c on the full width at half maximum of the parallel momentum distribution (FWHMp//). R2v/R2c is a measure of the exotic extent of the nuclear halo. Based on the obtained scaling law, FWHMp// can be used as an experimental observable to extract R2v/R2c and measure the exoticextent for the nuclear halo.     

Scaling of charge-changing interaction cross sections and point-proton radii of neutron-rich carbon isotopes

Charge-changing cross sections σ(cc) of stable and unstable nuclei ((9-11)Be, (14-16)C, and (16-18)O) on a carbon target were investigated at 300 MeV/nucleon. A phenomenological analysis based on the Glauber theory indicates an approximate, but universal, scaling of σ(cc) over a wide range of A/Z. This allows the determination of the density distributions of protons tightly bound in the nuclei. An application to (16)C, which is considered to be an anomalously deformed nucleus, indicates a systematic evolution of proton root-mean-square radii and has revealed for the first time a neutron skin effect in carbon isotopes. Being complementary to isotope-shift and electron-scattering experiments, the present method can open up a new approach to explore the structure of exotic nuclei.     

改进的Glauber理论和核–核反应总截面

利用Glauber理论系统计算了中、低能条件下核–核反应总截面.讨论了量子效应、库仑效应以及核子–核子碰撞同位旋效应对Glauber理论的修正.发现在应用Glauber理论计算中、低能核–核反应截面时,量子修正是重要的.利用修正了的Glauber理论,系统计算了从低能到高能大量稳定线附近的核–核反应总截面,在没有可调参数的情况下,都与实验结果较好地符合.     

利用改进的Glauber模型对非奇异核核反应总截面数据的拟合

在对反应总截面的理论计算中,现有的理论计算值与实验数据在高能区可以很好的符合，但在中能区理论值低于实验值约10％—20％.通过对计算核反应总截面的Glauber模型加入有限程修正，并对输入的核物质密度分布采用双参数的费米密度分布形式.计算结果表明，理论计算值对于没有奇异结构的核在低中能区和高能区，都与实验数据很好符合.     

Robust nuclear observables and constraints on random interactions

The predictions of the interacting boson model two-body random ensemble are compared to empirical results on nuclei from Z = 8-100. Heretofore unrecognized but robust empirical trends are identified and related both to the distribution of valence nucleon numbers and to the need for and applicability of specific, nonrandom interactions. Applications to expected trends in exotic nuclei are discussed.     

核反应总截面和奇异结构研究

本总结了晕和皮等奇异核子结构研究的现状,介绍了发现晕和皮现象的实验证据。然后集中介绍了利用奇异核反应总截面的实验测量和理论模型,从中提取奇异核物质半径,核内核子分布以及介质中的核子－核子碰撞截面等重要信息,我们将特别强调通过实验测量和理论模型之间的联系来研究奇异结构性质。     

Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei

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.     

Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei

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.     

Systematic CDCC calculations for ~11Be+p elastic scattering

Continuum discretised coupled-channels(CDCC) method with a ~(10)Be(0~+) + n two-body cluster model is applied to systematically analyze the elastic scattering of the halo nucleus ~(11)Be from the proton target at various incident energies below 100 MeV/nucleon.Using the renormalized ~(10)Be- p potential deduced from the ~(10)Be+ p elastic scattering data, the differential cross sections of ~(11)Be + p scattering are well reproduced by the CDCC calculations without any further adjustment parameters, demonstrating the applicability of this approach for describing the scattering of exotic nuclei based on the scattering of the less exotic core nuclei.