High Efficiency Photon Counting Detectors for the FAUST Spacelab Far Ultraviolet Astronomy Payload

We compare the performance of sealed tube microchannel-plate position sensitive detectors having transmission CsI photocathodes or opaque CsI photocathodes. These devices were developed for the FAUST Spacelab payload to accomplish imaging surveys in the band between 1300Å and 1800Å. We demonstrate that photocathode quantum efficiencies in excess of 40% at 1216Å have been achieved with the transmission and the opaque CsI photocathodes. The effect of the photoelectron trajectory on the spatial resolution is assessed. Spatial resolution of <70μm FWHM has been obtained and is maintained up to event rates of 5×104 sec-1. Background rates of 0.55 events cm-2 sec-1 have been achieved and low distortion (<1%) imaging has been demonstrated.