金/硅界面X射线剂量增强效应的Monte Carlo模拟  

Monte Carlo Simulation of Dose Enhancement Effect of Au/Si Interface Irradiated by X-Rays

作　　者：卓俊[1] 黄流兴[1] 牛胜利[1] 朱金辉[1] 

机构地区：[1]西北核技术研究所,西安710024

出　　处：《现代应用物理》2015年第3期168-172,共5页Modern Applied Physics

摘　　要：通过建立一个典型的金/硅界面结构模型,对X射线入射界面时的剂量增强效应进行了研究。采用Monte Carlo方法计算了不同能量X射线入射金/硅界面的输运过程。其中,对X射线产生的次级电子在介质中的输运,采用了单次碰撞直接模拟方法;对电子的弹性散射截面和非弹性散射截面,分别采用Mott微分截面和Born近似下的广义振子强度模型计算得到。研究计算了不同能量X射线入射下,金/硅界面的剂量增强系数及特定X射线能量下剂量增强系数随金厚度的变化规律。结果表明:X射线能量为几十至几百keV时,剂量增强效应最明显,最大剂量增强系数对应的X射线能量随距金/硅界面的距离增加而增加;金的厚度影响界面附近剂量增强效果,当X射线能量不变时,剂量增强系数随金的厚度增加而增加,并趋于饱和值。Dose enhancement factors are calculated with the Monte Carlo method for an Au/Si interface irradiated by X-rays. The mechanism of dose enhancement has been discussed and the detailed simulation is carried out by virtue of the secondary electron transportation. The Mott cross-section and the atomic generalized oscillator strength in the Born approximation are used to calculate the numbers of elastic and inelastic scattering electrons traversing in the solids, respectively. Dose enhancement factors in silicon induced by X-rays with different energy and different thickness of Au are presented. The results indicate that dose enhancement effect is stronger near the Au/Si interface when the energy of X-rays is in the range of tens of keV to hundreds of keV, and the X-ray energy related to the maximal dose enhancement factor increases with the distance from the Au/Si interface. For a given X-ray energy, the dose enhancement factor will increase with the increase of the thickness of Au until reaching the maximum eventually.

关 键 词：MONTE CARLO模拟 X射线 低能电子 剂量增强系数 

分 类 号：O562.5[理学—原子与分子物理]