微区X射线能谱信号实时梯形成形算法研究

Research on real-time trapezoidal shaping algorithm of X-ray energy dispersive spectroscopy

在能量色散谱仪(energy dispersive spectroscopy,EDS)中,特征X射线信号幅值提取是其进行元素分析的关键,数字成形算法则是现代X射线信号处理的核心所在。本文对硅漂移(silicon drift detector,SDD)探测器前置放大器输出信号进行了转化处理,针对调理后的双指数脉冲信号采用FPGA设计了一种高频率、高精度、参数可调的实时脉冲梯形成形算法。并使用理想双指数信号和实测的X射线特征谱信号验证了算法的可行性与实时性,与MATLAB双精度算法成形结果比较测试了算法精度。实验结果表明:该算法可在100 MHz频率下实时将双指数脉冲成形为梯形脉冲,成形效果稳定。其实际信号成形结果与双精度算法结果保持一致,平顶幅值相差在0.6%以内。

In EDS(energy dispersive spectroscopy, EDS), amplitude extraction of characteristic X-ray signals is the basis for elemental analysis, and digital forming algorithms are the heart of X-ray signal processing. In this paper, the output signal of the preamplifier of SDD was first converted, and a high-frequency, high-precision, and parameter-adjustable real-time pulse trapezoidal shaping algorithm was designed by FPGA for the double index after conditioning. The feasibility and real-time ability of the algorithm were verified by using the ideal double exponential signal and X-ray signal, and the precision was tested by comparing the forming results with the MATLAB double precision algorithm. Experimental results showed that the algorithm can form the double exponential pulse into trapezoidal pulse in real time at 100 MHz frequency, and its effect was stable. The actual signal forming result was basically consistent with the double precision algorithm result, and the flat top amplitude difference was within 0.6%.