Experimental measurement of spatial position jitters of a high-energy radiographic source
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摘要: 高能闪光照相中光子散射会导致接收图像清晰度降低,影响照相客体界面和密度的分辨精度。使用网栅相机可显著降低散射光子影响,提高图像分辨能力,但同时要求X射线源空间位置更加稳定以减少信号光子在网栅结构中的损失。采用小孔成像的方法测量神龙一号直线感应加速器X射线源焦斑分布,计算焦斑的质心位置和半高全宽大小,分析电子束聚焦状态改变对X射线源空间位置和大小的影响。实验结果表明,电子束聚焦状态改变会导致射线源质心位置及尺寸大小发生明显变化。在恒定聚焦状态下,源质心抖动及大小变化均可稳定在较小范围。 ;Abstract: In flash-radiography, scattering photons will decrease the definition of receiving images, which limits the resolving power of the interface and the density of the object for radiography. The anti-scatter grid camera is able to improve the picture resolving power due to a great reduction of scattering photons, which, in the meantime, demands a much more stable spatial position of the X-ray source in order to reduce the loss of signal photons in the anti-scatter grid structure. The pinhole imaging method is applied to measure the spatial distribution of the Dragon-I LIA X-ray source, by which the centroid and the FWHM of the spot can be calculated, and to analyze the influence of the electron beam focusing to the displacement and the size of the source spot. Experimental results demonstrate that a variation in electron beam focusing will lead to a distinct change of the spatial position and the size of the radiographic source. It can also be seen that the jitter of the source centroid and the change of the spot size can be kept in a small range when the focusing of the electron beam remains invariant.
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Key words:
- linear induction accelerator /
- X-ray source /
- centroid jitter /
- pinhole imaging
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