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The second-order distorted wave Born aPl6roximation (DWBA) method is employed to investigate the triple differen- tial cross sections (TDCS) of coplanar doubly symmetric (e, 2e) collisions for magnesium at excess energies of 6 eV-20 eV. Comparing with the standard first-order DWBA calculations, the inclusion of the second-order Born term in the scattering amplitude improves the degree of agreement with experiments, especially for backward scattering region of TDCS. This indicates that the present second-order Born term is capable to give a reasonable correction to DWBA model in studying coplanar symmetric (e, 2e) problems of two-valence-electron target in low energy range. 相似文献
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The momentum-space coupled-channels-optical (CCO) method is used to study the resonances in electron oxygen collision in the energy region of 9-12 eV, Present results have shown agreement with the available experimental and theoretical results, and new positions of resonances are found by the comparison of total cross sections, 相似文献
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本文使用扭曲波波恩近似方法(DWBA)研究了共面对称条件下钙原子的电子碰撞电离反应((e,2e)反应),在DWBA理论的基础上,考虑了原子极化势和离子极化势对三重微分散射截面的影响.采用发展的DWBA方法,我们研究了出射电子能量从6.75 e V到29.25 e V范围内电子与钙原子的碰撞电离过程,计算了电离三重微分截面.通过与已有理论和实验数据进行比较发现,离子极化势对钙原子的共面对称(e,2e)反应散射微分截面有较大的影响,很好的描述了碰撞电离微分截面的结构效应,特别是在散射角度较小时(≦60o),本文计算结果与实验测量非常一致. 相似文献
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Study of (e, 2e) process on potassium at 6 eV-60 eV above threshold in a second-order Born approximation 下载免费PDF全文
The standard distorted wave Born approximation(DWBA) method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target.Second-order DWBA calculations have been preformed to investigate the triple differential cross sections(TDCS) of coplanar doubly symmetric(e,2e) collisions for the alkali target potassium at excess energies of 6 eV-60 eV.Compared with the previous first-order DWBA calculations,the present theoretical model improves the degree of agreement with experiments,especially for the backward scattering angle region of TDCS.This indicates that the present second-order Born term is capable of giving a reasonable correction to the DWBA model in studying coplanar symmetric(e,2e) problems in low and intermediate energy ranges. 相似文献
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Investigations of resonances and threshold behaviors in positron-helium scattering have been made using the momentum-space coupled-channels optical method.The positronium formation channels are considered via an equivalent-local complex potential.The s-wave resonances and the Wigner cusp feature at the positronium(n = 1) formation threshold are compared with the previous reports.The p-and the d-wave resonances and a Wigner cusp feature at the positronium(n = 2) formation threshold are reported for the first time. 相似文献
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We used the close-coupling optical (CCO) approach to investigate the open-shell carbon atom. The elastic cross sections have been presented at the energies below 90eV, and the present CCO results have been compared with other theoretical results. We found that polarization and the continuum states have significant contributions to the elastic cross sections. The present calculations show that the CCO method is capable of calculating electron scattering from open-shell atoms. 相似文献
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The inelastic scattering of electron from oxygen for the 2s^2 2p^4 ^3P→2p^3 3s^3S^0 transirion is studied using the momentum-space coupled channel optical method at 15, 17.5, 20, 22.5, 25, 27.5, 30, 50, and 100eV. Direct ionization cross sections, i.e. differential and integral cross sections, are reported. Important continuum states are included in the coupled channel calculation via a complex equivalent-local optical potential. The present results are compared with the available experimental data and other theoretical calculation results. 相似文献
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针对隐式蒙特卡罗方法模拟高温热辐射输运问题时存在的“辐射强度计算误差时间空间分布严重不均匀”现象,通过理论分析和数值模拟手段,找到决定误差大小的主要因素为“网格内的辐射径迹长度记录数”.据此提出“隐式蒙特卡罗全局降方差方法”并推导相应的计算公式.该方法主要包含如下3个关键技术:1)针对辐射输运蒙特卡罗模拟的自适应动态分配源粒子方法; 2)与自适应动态分配源粒子相匹配的动态权窗设计技术及粒子权无偏估计算法; 3)辐射强度的解析估计降方差方法.针对这3个关键技术,设计蒙特卡罗数值模拟方案,编写相应的数值模拟程序模块.典型辐射输运问题模拟结果显示:隐式蒙特卡罗全局降方差方法能够使网格辐射强度计算误差在整个时空范围内分布相对比较均匀,最大误差可控,计算效率提升10倍左右.新方法在激光惯性约束聚变的黑腔辐射输运模拟应用中取得了显著效果. 相似文献