A large-area VUV photosensor with gain from photoelectron acceleration and concentration

We report the results of the development of a new photosensor with large area and high gain. The photoelectrons from a 48-mm-diameter CsI photocathode are accelerated to high voltage and electrostatically concentrated, rather than imaged, onto the surface of an 8-mm-diameter semiconductor detector. The amplitude of the photoelectron signals initiated by a constant-intensity high-stability (<1%) pulsed xenon lamp is approximately linear with the accelerating voltage in the 10 to 20-kV region. Signal non uniformity over 70% of the photocathode area is below 6%