Abstract
Caesium-antimony photocathodes were processed in a vacuum of the order of 10−9 torr in two types of ultra-high vacuum systems, namely, (i) a conventional rotary pump-three stage glass mercury diffusion pump combination system and (ii) a sorption pump-titanium sputter ion pump combination system. Enhancement in white light sensitivity was observed when the photocathodes were processed in the ion pump uhv system in comparison with the diffusion pump system. A brief discussion is presented in the light of the residual gas contents in evacuated tubes processed in uhv systems. The photoelectric yield of semitransparent caesium-antimony photocathodes depends critically on the thickness of the original antimony film. Hence, the relationship, photoelectric yield (μA/lm) against percentage transmission of antimony film has been established. It is found that thin film caesium-antimony processed from an antimony film with 70% transmission yields an efficient photocathode in both types of uhv systems.
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