激光高能X射线成像中探测器表征与电子影响研究  

Detector characterization and electron effect for laser-driven high energy X-ray imaging

作　　者：张天奎[1] 于明海 董克攻[1] 吴玉迟[1,2] 杨靖[1] 陈佳[1] 卢峰[1] 李纲[1] 朱斌[1] 谭放[1] 王少义[1] 闫永宏[1] 谷渝秋[1,2] 

机构地区：[1]中国工程物理研究院激光聚变研究中心,等离子体物理重点实验室,绵阳621900 [2]上海交通大学IFSA协同创新中心,上海200240

出　　处：《物理学报》2017年第24期131-141,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11505166,11174259,11375161,11405159);等离子体物理重点实验室基金(批准号:9140C680301150C68297,9140C680302130C68242);国家重点研发计划(批准号:2016YFA0401100)资助的课题~~

摘　　要：基于激光尾场加速电子的高能X射线源具有高光子能量与小源尺寸的特点,在高空间分辨无损检测方面发挥着十分重要的作用.在X光机上测量了CsI针状闪烁屏、锗酸铋(BGO)闪烁阵列与DRZ闪烁屏的本征空间分辨率,并模拟了三类探测器对高能X射线的能量沉积响应,其中CsI针状闪烁屏的空间分辨率高达8.7 lp/mm.采用Ta转换靶产生的高能X射线开展透视照相,能够分辨最高面密度33.0 g/cm^2的两层客体结构.开展了X射线照相、X射线与电子混合照相以及电子照相三种情况的比对实验,在X射线产额不足或探测效率不够情况下采用X射线与电子混合透视照相的方案,以牺牲对比度为代价,能较大程度地提高图像信号强度.High energy X-ray sources based on laser-wakefield accelerated electron beams have several important advantages,including high photon energy and small source size, and have many important applications such as high resolution radiography in non-destructive testing. Firstly, the thickness of electron converter is optimized with the targets Ta, W and Pb each with an optimal thickness of 2 mm. We calibrate the intrinsic spatial resolution of CsI needle-like scintillation screen, bismuth germanium oxide（BGO） scintillation array and DRZ scintillation screen with an X-ray tube. And the spatial resolution of CsI needle-like scintillation screen is as high as 8.7 lp/mm. The energy deposition responses of these three detectors to high X-ray are also simulated. Experiments show that the features of a two-layer object can be resolved up to an area density of 33.0 g/cm^2 by using the high X-ray source generated by injecting laser-wakefield accelerated electron beam into a Ta convertor target. Experiment that compares X-ray radiography, mixed radiography of X-ray and electron, and electron radiography, is also carried out. Since low X-ray yield and low detection efficiency are two serious problems in high energy X-ray radiography based on laser-wakefield accelerated electron beams, we propose and prove a method of improving image signal intensity greatly at the cost of image contrast by adopting the mixed radiography of X-ray and electron.

关 键 词：激光尾场加速 高能X射线 无损检测 成像探测器 

分 类 号：O434.1[机械工程—光学工程]