Research on Relative Detection Efficiency of Microchannel Plates with KBr and CsI for 70～1000 eV Photons
There are strong application demands for soft X-ray and vacuum ultraviolet detection imaging in deep space exploration,X-ray astronomy and many other fields.In this research,standard 25 mm diameter micro-channel plates(MCPs)with the hole diameter of 5 μm and bias angles of 12° and 16° are utilized.The input sur-face of MCP is divided into three areas,and KBr and CsI with different thickness of 50 nm,100 nm and 150 nm and different electrode depths of 0.5D,2D and 3D are evaporated respectively as reflective cathodes.The relation-ship between direct current gain and operating voltage of a single MCP is tested,and the relationship between secondary electron yield and incident electron energy of CsI and KBr thin films is studied.By using ceramic met-allization and Kovar welding,integral tube shells are sealed tightly to standard CF35 vacuum flanges,and multi-ple sets of MCP detectors are fabricated.The relationships between the relative output light intensity of different areas of MCP and the incident photon energy,and the MCP operating voltage are tested in the synchrotron radia-tion light source,and the optimized thicknesses of CsI and KBr films and the optimized parameters of MCP are obtained.The research results indicate that the detection efficiency of MCP for 70～1000 eV photons after coating is higher than that of bare plates.At operating voltage of 700 V,the maximum relative gain of coated CsI to the bare plate is about 2.4,and the maximum relative gain of coated KBr to the bare plate is about 2.The recommended coating thickness range,electrode depth range,and bias angle are 100～50 nm,1.5 D～3D,and 12 °,respectively.
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