Study Of Influence Of Scintillator Thickness On The Imaging Quality Of X-ray Imaging Detectors

X-Ray imaging detector consists of a scintillator conversion screen, an opticalsystem (lens and mirror) and an area array CCD. The image quality is affected by theperformance of the detector directly, so it is significant to study and optimize theX-Ray imaging detector.There are some factors that can effect on the performance of the detector: thescintillator material (absorption efficiency, decay time), the scintillator thickness, thedetective quantum efficiency of the visible light detector and the coupling efficiencybetween the visible light detector and the scintillator. The scintillator, convertingincident X-ray photos into visible light that imaged on the surface of Charge CoupledDevice (CCD) by the optical system, is the key section of the synchrotron radiationX-ray imaging detector.The performance of scintillator plays a significant role on the resolution andcontrast of the images which is taken by X-ray imaging detector. The detectormatched with an optimal thickness of scintillator is conductive to improve theresolution of images. However, users of Shanghai Synchrotron Radiation Facility(SSRF) neglected that the scintillator could influence the images quality when theyperformed their X-ray imaging experiments. Selecting the scintillator with a suitablethickness can help us get good images to achieve outstanding experimental result.Following works have been done in this dissertation:Firstly, the reason of the effect of scintillator thickness on the performance ofX-Ray imaging detector was analyzed.Secondly, the connection between scintillator thickness and resolution of detectoris found, and contribute to calculating the best scintillator thickness. Optimalthickness of scintillator for every objective lens is calculated by the way ofmathematical computations.Finally, X–ray imaging experiments were made to verify optimal thickness ofscintillator that was calculated in second step. In experiments, Resolution Target wasimaged bay the detector of PCO2000whose scintillators conversion screen wasreplaced by YAG scintillators of thickness. The images were analyzed with themethod of contrast, then we got the best thickness of scintillator for everyobjective lens. And the result of experiments confirmed the prediction. Users of SSRF will get better results of X-ray imaging experiment than beforewhen they chose the scintillator with the optimal thickness matched with theobjective lens.