Performance of a large-area microchannel plate photon counting intensifier

A 75 mm diameter microchannel plate (MCP) intensifier has been developed for astronomical applications. The intensifier incorporates a semi-transparent photocathode, three MCPs in a Z- stack configuration, and a P20 phosphor screen in a dual proximity focused arrangement. The input MCP is a thin 40:1 channel plate which is conditioned to run at low gain and hence act as an ion barrier for the succeeding 80:1 chevron pair. The intensifier has been incorporated into a CCD readout system and has undergone extensive laboratory testing. The preconditioning of these 75 mm diameter channel plates required a large area, highly uniform electron scrub beam, this has led to the development of a novel electron gun. The design of the 75 mm intensifier and the novel electron gun are described. Results from the laboratory evaluation of the intensifier are presented. Flat field illumination showed the existence of self- exciting channels in a hexagonal pattern. Finally, a future UV or x-ray detector based on this design and incorporating large area MCPs is discussed.