X射线探测器双指数信号时间常数  

Time constant of double exponential signal for X-ray energy spectrum detector

作　　者：程隆军 殷伯华[1,2] 孙博彤 许广鹿 王文博 韩立 CHENG Longjun;YIN Bohua;SUN Botong;XU Guanglu;WANG Wenbo;HAN Li(Institute of Electrical Engineering,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院电工研究所,北京100190 [2]中国科学院大学,北京100049

出　　处：《核技术》2021年第9期51-59,共9页Nuclear Techniques

基　　金：中国科学院科研仪器设备研制项目(No.YZLY201901)资助。

摘　　要：在X射线能谱测量系统中,时间常数是影响梯形成形效果的重要因素,准确测量双指数脉冲信号的时间常数有利于获得较好梯形成形效果。本文研究了一种基于最小二乘法的快速拟合双指数脉冲算法,用于测量梯形脉冲成形中的时间常数,不仅从理论上证明了该算法的合理性,而且用含有5%标准差噪声的仿真信号和X射线探测器接收55Fe放射源输出的成形脉冲信号验证了该算法,拟合优度R2均超过了0.95。将本文快速拟合算法与MATLAB中cftool工具箱的拟合算法进行对比,结果显示:在满足拟合优度超过0.95的情况下,本文算法的运行速度比cftool中算法快两个数量级。[Background]In the X-ray energy spectrum measurement system,the time constant is an important factor affecting trapezoidal pulse shaping.Accurate measurement of the time constant of double exponential pulse signals is beneficial to obtaining a better trapezoidal pulse shaping.[Purpose]This study aims to propose a fast fitting double exponential pulse algorithm for measuring the time constant in trapezoidal pulse shaping.[Methods]First of all,the linear regression method based on the least square method was adopted to convert nonlinear fitting linear fitting.Then,functional expression of double exponential pulse signal was fitted by fast trapezoidal pulse shaping,and the feasibility of time constant measurement in trapezoidal forming by fast fitting double exponential algorithm was verified by MATLAB programming simulation.Finally,the practicability of the algorithm was evaluated by experimental pulse data of 55Fe radiation source received by X-ray silicon draft detector(SDD).Goodness-of-fit R2 of this algorithm was compared with that of cftool toolbox of MATLAB on both the simulation data and experimental data.[Results]The goodness of fit R2 of proposed algorithm exceeds 0.95 for both the simulated signal with 5%standard deviation noise and the shaped pulse signal of experiments.When the goodness of fit exceeds 0.95,the running speed of this algorithm is 2 orders of magnitude faster than that in cftool toolbox of MATLAB.[Conclusions]The algorithm of this paper possesses high fitting degree,fast calculation time,hence suitable for real-time measurement of time constant of double exponential pulse signal in embedded system.

关 键 词：微区能谱 梯形成形 双指数拟合 最小二乘法 

分 类 号：TL824[核科学技术—核技术及应用]