楔条形阳极位置灵敏探测器图像非线性研究

The imaging non-linearity of position-sensitive detector based on wedge-strip anode

基于楔条形阳极位置灵敏探测器的成像原理和二维傅里叶变换理论,提出了一种建立该类探测器成像模型的方法,进而模拟了探测器的成像效果,仿真了成像的几何非线性,仿真图像与实际图像基本符合。仿真结果表明:在阳极面板半径多出微通道板半径2P(P为阳极周期宽度)和电子云分布半宽度D为1.3P时,该类探测器的成像线性良好;电子云过小即D<P时,楔条形阳极对电子云欠采样,出现成像调制扭曲(modulation),且随着D的进一步变小而更加明显;在电子云面积过大即D>5P时,电子云超出楔条形阳极工作区域,成像边缘扭曲十分明显。

In order to improve the imaging performance of wedge-strip anode position-sensitive detector and remove its imaging non-linearity, we develop an imaging model according to its working principle. First, the principle of wedge-strip anode position-sensitive detectors is introduced, the imaging nonqinearity brought by wedge-strip anode＇s charge mismeasurement is analyzed; then a method is proposed to build its imaging model based on two-dimensional Fourier transforms theory; at last, using this model, we simulate the detector imaging process and its imaging non-linear,and the simulation image is in line with the actual image. The results indicate that when the charge cloud size is too small, D〈5P, the wedge-strip anode undersamples the charge cloud, then the image shows obvious modulation distortion; when the charge cloud size is too large,D〉5P,part of cloud is out of working area of wedge-strip anode,then the image shows obvious edge distortion.