Progress in soft x-ray and UV photocathodes

摘要

We present investigations on the improvements in quantum detection efficiency (QDE) of microchannel plate (MCP) detectors resulting from the application of various photocathode materials. Nine different photocathode materials were deposited and their QDE measured in the soft x-ray and UV region from 12 angstrom to 1850 angstrom. Four of these materials (CsCl, RbCl, RbI, BaCl) significantly enhance the QDE performance of bare MCPs, and five materials were proven unsatisfactory (AgCl, LiCl, LiI, LiF, MgBr). CsCl has very high (greater than 90%) short wavelength QDE and both CsCl and RbI have UV QDE in the region of 40%. Our studies also include life testing of a KBr photocathode for a period of over 5 years. This shows good stability, and the angular response and photoemissive characteristics over time are described. The effects of long wavelength QDE activation of KBr by exposure to 2537 angstrom photons are discussed.