电子照相技术成像模拟研究

Study on imaging simulation of electronic photography

针对高能电子照相的关键物理过程开展蒙特卡罗照相模拟研究,采用Geant4围绕2.5 GeV电子在四极透镜组内的输运、电子与物质相互作用衰减等照相基本过程展开研究。通过设计不同材料、不同厚度的含缺陷平板作为模拟照相客体,开展放大型电子照相系统缺陷分辨能力模拟。此外,采用不同材料、不同厚度的台阶样品,模拟获得了电子束流穿过相应面密度材料后的线扩展函数,进一步评估电子照相对实心客体的探测分辨能力。

High energy electron radiography is a useful nondestructive method for density material diagnosis.The higher the kinetic energy,the stronger penetrability the electron has.Thus electron with GeV energy is considered for probing the density material.This paper aims at 2.5 GeV electron radiography.The key processes of radiography are studied by Monte Carlo simulation.All simulations are carried out by Geant4 code.Firstly,basic physical processes including the transport of electrons in the quadrupole lens group and the attenuation of the interaction between electrons and matter are constructed by Geant4 code.Some details about the physics setup are given.Four samples of different materials and thickness,with voids inside,are designed as the object of simulation radiography.Other necessary geometries for electronic photography such as quadrupole and pixel detector are built as well.Then a large-scale electronic photography is simulated.In addition to this,two step samples made of copper and tungsten,respectively,are employed as object for the radiography simulation.In the simulation,collimated line electron source radiates objects,then the line spread function of the electron beam passing through the different area density is obtained.Based on the simulated results,evaluation about the detection and resolution ability of 2.5 GeV electron radiography is shown.