A large-area VUV photosensor with high gain by means of 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 with 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 pulsed xenon lamp of constant intensity and high stability (instability <1%) is approximately linear with the accelerating voltage in the 10 to 20 kV region. Non uniformity of the signal amplitude over 70% of the photocathode area is below 6%