Micro-channel Plates(MCPs) are an important part of ultraviolet photon counting imaging detectors. They can intensify single particles or photons by the multiplication of electrons via secondary emission.Thus, the MCP gain has an very important influence on the performance of ultraviolet photon counting imaging detectors. In this article, influence of MCP gain on decoding accuracy is studied by using Monte Carlo method. Simulation results show that decoding error is large when MCP gain is low,and MCPs shoud have at least 106 gain to ensure accurate decoding. At the same time, influence of MCP gain on decoding error was tested by using ultraviolet photon counting imaging system based on TWA(Tetra Wedge Anode,TWA). Experimental results are consistent with the theoretical analysis and simulation.
Glass preparing and integrating technologies are important in construction of grazing incidence optics, and these vital process are corresponding to the concentrating efficiency directly. Thermal slump glass under pressure supplied by stainless cloth with mass has been shown in this paper, and we obtained a below 1 nm roughness by coating Ir on slump glass segments. Then, A novel 6 dimensional integrating system for grazing incidence optics was developed to assemble all segments together, carbon ribs and epoxy were applied in the integrating process to make fragile glass segments stable. Finally, a glass-carbon-epoxy structure grazing incidence optics was developed and focal spot with diameter of 6 mm was obtained with parallel light. This kind of grazing incidence optics is supposed to concentrate large area X-ray photons to small area for reducing cost on space applications.
Cesium iodide (CsI) photocathode is widely used in various UV (ultraviolet) detecting devices because of its high quantum efficiency (QE) and good stability under short exposure to humid air. In this paper, the performance of the opaque CsI photocathode is studied, including imaging performance, influence of humidity on the quantum efficiency and the stability of the CsI photocathode under FUV irradiation. In the experiment, the input surface of the MCP was evenly divided into four parts. Different thicknesses of the CsI photocathode were deposited directly on the front surface of micro-channel plates (opaque photocathode). The response of different thicknesses and the stability of UV quantum efficiency of CsI photocathode under FUV illumination were studied by using UV monochromator. At the same time, the influence of humid air exposure on the quantum efficiency of CsI photocathode was tested. According to the experimental results, a FUV detector (vacuum tube) based on opaque CsI photocathode was fabricated and the quantum efficiency of the detector was tested. Absolute quantum efficiency of the FUV detector is over 15.5% at 121nm.
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