Lucy-Richardson迭代解谱在X射线荧光分析的应用  

An Application of Lucy Richardson Iterative in X-Ray Fluorescence Analysis

作　　者：祝宇轩 陆景彬[1] 赵晓帆[2] 刘晓艳[4] 崔苇苇[2] 李炜[2] 王于仨[2] 吕中华 陈勇[2] ZHU Yu-xuan;LU Jing-bin;ZHAO Xiao-fan;LIU Xiao-yan;CUI Wei-wei;LI Wei;WANG Yu-sa;LU Zhong-hua;CHEN Yong(College of Physics,Jilin University,Changchun 130012,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Physical Science and Technology,Heilongjiang University,Harbin 150080,China)

机构地区：[1]吉林大学物理学院,吉林长春130012 [2]中国科学院高能物理研究所,北京100049 [3]中国科学院大学,北京100049 [4]黑龙江大学核科学与技术学院,黑龙江哈尔滨150080

出　　处：《光谱学与光谱分析》2021年第9期2823-2828,共6页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(U1838201,U1838202,U1838105)资助。

摘　　要：硬X射线调制望远镜是我国第一颗X射线天文卫星,其载荷低能X射线望远镜采用了SCD型探测器CCD236,主要对能量在0.7~13.0 keV的软X射线光子进行观测。卫星发射前,需要对探测器进行详细的性能标定,其中包括能量响应矩阵的标定。能量响应矩阵是能谱分析的关键。CCD236探测器输出能谱并不是观测光源的真实发射谱,而是发射谱与探测器能量响应矩阵的卷积结果。一般可以通过直接反卷积的方法还原光源的真实能谱。解谱过程可以看作是一维成像问题,利用能量响应矩阵与输出能谱进行反卷积解谱。常用的反卷积算法为Lucy-Richardson迭代算法,其利用条件几率的贝氏定理反复进行运算,进而对输出能谱进行反解,得到观测光源的真实发射能谱。通过能量响应矩阵对CCD236探测器的^(55)Fe测量能谱进行解谱。经过解谱,能谱的能量分辨从144.3 eV提升到了65.6 eV@5.9 keV,连续谱成分被明显地抑制,提高了能谱的峰背比。反解能谱由两个半峰全宽很小的(<70.0 eV)高斯峰组成,两成分的强度比为8.4,能够很好地表征真实发射谱的结构。利用这种方法可对材料X射线荧光谱进行解谱,还原材料的荧光谱,提高能谱的能量分辨。反解结果中主要元素各类荧光线通过解谱彼此独立,能谱峰背比很高,可以很好地用于X射线荧光分析中,提高荧光谱的质量。Hard X-ray Modulation Telescope(HXMT)is China’s first X-ray astronomical satellite.Low Energy X-ray Telescope(LE)is one of the HXMT’s payloads,which used a special swept charge device(SCD)CCD236 detector to observed photons in an energy band of 0.7~13.0 keV.The CCD236 detectors need to be calibrated well before the launch of HXMT,including the calibration of the energy response matrix,which is the key to energy spectrum analysis.The output spectrum of CDD236 is not the actual emission spectrum of the observation source but the convolution result of the emission spectrum and the energy response matrix(RSP).Generally,we can apply a direct deconvolution method to restore the spectrum of the source.A general deconvolution algorithm is the Lucy-Richardson iterative method which uses the Bayes theorem of conditional probability to carry out repeated operations.Using this method,one can use the RSP to deconvolute with the output spectrum,and restoration of the actual spectrum can be obtained by this method.The spectrum of ^(55)Fe radioactive source can be restored using LR iterative algorithm for verifying the robustness of this method.After the iteration,the energy resolution is optimized from 144.3 to 65.6 eV@5.9 keV,and the continuous plateau is obviously suppressed.The restoration spectrum,which is composed of two Gaussian peaks with very narrow FWHM,can well characterize the structure of the real emission X-ray of ^(55)Fe.At the same time,the X-ray fluorescence spectrum of a composite was inversely solved by this method,and the X-ray fluorescence spectrum of the material was reproduced by iteration.The FWHM of each spectrum line was very small,and the main spectrum line of Ag element in the material was changed into an independent line spectrum by iteration.This kind of inverse energy spectrum can be well used for the analysis of element composition.

关 键 词：X射线探测器CCD236 Lucy-Richardson迭代 X射线荧光分析 

分 类 号：O562.31[理学—原子与分子物理]