Advances in microchannel plates and photocathodes for ultraviolet photon counting detectors

Abstract

A new method of fabricating microchannel plates has been investigated, employing microcapillary arrays of borosilicate glass that are deposited with resistive and secondary emissive layers using atomic layer deposition. Microchannel plates of this kind have been made in sizes from 33 mm to 200 mm, with pore sizes of 40 μm and 20 μm, pore length to diameter ratios of 60:1, bias angles of 8°, and open areas from 60% to 83%. Tests with single MCPs and MCP pairs have been done and show good imaging quality, gain comparable to conventional MCPs, low background rates (~ 0.085 events sec^-1 cm^-2), fast pulse response, and good ageing characteristics. The quantum efficiency for bare and alkali halide coated MCPs is similar to conventional MCPs, and we have also been able to deposit opaque GaN(Mg) cathodes directly onto these MCPs.