用蒙特-卡罗方法模拟质子X荧光分析中的荧光增强因子

本文用蒙特-卡罗方法模拟质子激发X荧光分析中的一次和二次荧光强度,从而得到荧光增强因子。文中利用模拟计算程序,在改变入射质子能量、入射角、x射线出射角及分析样品的成分和含量的条件下,分别计算了荧光增强因子。此外,还计算了质子激发标准合金钢样品的荧光增强因子,得到的     

离子束辅助沉积对类金刚石膜结构影响的计算机模拟

采用分子动力学(MD)模拟研究了离子束辅助沉积(1BAD)生长类金刚石(DLC)膜的物理过程.分 别选C₂分子和Ar离子作为沉积源和辅助沉积粒子.改变Ar的入射能量和到达比(A r／C)，研 究了它对DLC膜结构的影响.重点讨论了Ar辅助沉积引起表面原子的瞬间活性变化对薄膜结构 产生的影响.分析表明，由于Ar离子的轰击引起的能量和动量的传递，大大地增强了C原子在 表面的反冲动能及迁移概率，增加了合成薄膜的SP³键含量.研究结果和实验 观察一致，并从合成机理上给出了一些定量解释. 关键词： 类金刚石膜 离子束辅助沉积 分子动力学模拟     

注入离子在无定形固体靶中投影射程分布的统计特性

用基于两体碰撞近似的动态蒙特-卡罗模拟方法和Boltzmann输运方程近似解法,研究注入离子在无定形固体靶中投影射程分布的统计特性.讨论注入物理参数对表征射程统计分布的平均投影射程、分布的标准偏差、偏度和峰度等的影响.计算结果与有关实验数据比较符合得较好. 关键词：     

核半径的弥散效应和形变效应

本文采用Yukawa折迭型密度分布函数, 在计及椭球形变和四面对称体形变的情况下给出了核电荷半径的计算公式. 对55种元素148个核素所作的计算表明, 计算值与实验值之间的总体偏差为0.034fm, 与参数较多的小液滴模型结果相近; 且可克服Z^1/3律在解释某些跨过大壳的同位素系列核半径变化时所遇到的困难. 本文还通过分析不同核素之间核表面宽度的涨落与中子壳层结构的关系, 解释了同位素核半径的精细结构.     

低能CU6团簇在CU(001)表面和AU(001)表面沉积的分子动力学模拟研究

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Atomistic Simulation of He Clustering and Defects Produced in Ni

Using the molecular dynamics method, the stability of small He-vacancy clusters is studied under the condition of the high He and low vacancy densities. The result shows that there is a competition between He atoms detrapped and self-interstitial atoms （SIAs） emitted during the clustering of He atoms. When the He number is above a critical value of 9, the SIA emission is predominant. The SIA emission can result in deep capture of He atoms since the binding energy of He to a He-vacancy cluster is increased with the number of SIAs created. The cluster thus grows up. In addition, more SIAs are created when the temperature is elevated. The average volume of a He atom is increased. The cluster expansion takes place at high temperature.     

低能原子簇轰击金属薄膜引起的级联碰撞(Ⅰ) 高能反冲原子

用分子动力学模拟研究能量为1 keV/atom的Au原子簇和0.2keV/atom的Al原子簇轰击金薄膜产生的级联碰撞。分子动力学模拟结果表明,原子簇轰击后,靶原子的反冲能谱加宽。与同样速度的单原子轰击比较,最大反冲能较后者高2—5倍。原子簇轰击后的多次碰撞及运动原子间的碰撞增加了靶原子的反冲能。还用经典力学守恒定律分析了两个碰撞的运动原子间的能量转移。     

低能原子簇轰击金属薄膜引起的级联碰撞(Ⅰ)——高能反冲原子

用分子动力学模拟研究能量为1keV/atom的Au原子簇和0.2keV/atom的Al原子簇轰击金薄膜产生的级联碰撞。分子动力学模拟结果表明,原子簇轰击后,靶原子的反冲能谱加宽。与同样速度的单原子轰击比较,最大反冲能较后者高2—5倍。原子簇轰击后的多次碰撞及运动原子间的碰撞增加了靶原子的反冲能。还用经典力学守恒定律分析了两个碰撞的运动原子间的能量转移。 关键词：     

MONTE CARLO STUDIES OF RADIATION DAMAGE INDUCED BY FUSION:DYNAMIC SIMULATION OF SPUTTERING

In this paper, the sputtering caused by fusion of ⁴He particles in the first wall materials is investigated by using the dynamic Monte Carlo simulation, which is based on the binary collision approximation. The dependences of sputtering yields on the incident energy and angle, as well as the comparisons of results calculated using the Monte Carlo methed with results from experiments, are discussed. Energy spectrum and angular distributions of sputtered species, the depth of origin of the sputtered particles as well as range distributions of incident ions are given. From a comparison between the related experimental data and the calculated results with static and dynamic simulation it has been found that a better agreement is obtained for dynamic simulation.