Design And Key Technology Research Of CsI(Tl)X-ray Detector

With the development of X-ray detection technology,scintillator detectors have become the hottest and best applied X-ray image detectors.Among them,X-ray detectors based on Tl-doped cesi?m iodide crystal have attracted attention because of its low cost and excellent detection performance.As the core parts of the detector,the light conversion properties and the structural design of the detector films are important factors for improving the imaging quality of the detector.In this paper,from the perspective of improving the light conversion efficiency of the detector,The CsI: Tl thin film was studied from the film formation process to the film thickness,and the structure matching of the detection module was also designed.The specific work is as follows:Firstly,the CsI: Tl X-ray direct detection component was modeled and simulated through the use of the Geant4 software simulation method,several factors of its detection efficiency were explored.By examining the thickness of the film,the size of the X-ray source,and the detection distance,the impact of its detection efficiency was explored.The film thickness,X-ray source size,and detection distance were simulated to explore the impact of its detection efficiency improvement.The simulation results show that the absorptivity and transmission loss of the film are the important reasons that the film thickness affects the light-to-light conversion.When the detection source is fixed,the light-to-light conversion efficiency increases first and then decreases with the increase of the film thickness.When the energy of the X-ray source increases,the X-ray penetration increases,the transmission loss in space decreases and the conversion efficiency increases.However,an excessively high X-ray source can easily cause radiation damage to subsequent detectors and affect their lifetime.The X-ray detector's conversion yield and detection distance are inversely related in the soft X-ray range while they are linearly decreasing in the hard X-ray range.Secondly,the CsI: Tl thin film was prepared by the laboratory process and the growth of its crystal structure was studied in detail.The stable nucleus is stacked discretely on the substrate like the island structure,The island-like structure undergoes the process of coalescence and eventually forms the micro-col?mnar structure.At the same time,the film has the characteristic of growing along the original growing crystal direction.It was found through experiments that the quality of the micro-pillar structure of the CsI: Tl film has an important relationship with its growth orientation,the influence of the preferred orientation on the crystal structure and light-to-light conversion.The thin film under high-strength single-preferred orientation has a regular crystalline structure,uniform and full grains,and high light-to-light conversion performance.Afterwards,the col?mnar growth of the thin film was optimized from the direction of the film deposition rate,and the performance parameters of the CsI: Tl thin film under the optimal conditions of the current laboratory preparation were given.Finally,the film wrapping and reflective layer and CCD arraying were explored.On the basis of the experimental preparation of antimony-doped lanthan?m iodide thin films,the coated reflective layer was plated and tested by steady state fluorescence spectroscopy.The CCD array matching was studied in detail and the structure of the detection module was optimized.Finally,the relevant structural parameters of the X-ray detection assembly were designed and tested for imaging.