A study on the activation technique of GaAs:Cs-0 NEA photocathodes

In this paper, a large activation and analysis system is introduced, which consists of automatic spectral response recording equipment, x-ray photoelectron spectrometer and ultrahigh vacuum chamber. Then, activation and on-line spectral response measurement are described. For the first time, on-line measured spectral response curves of GaAs:Cs-O NEA photocathodes are presented. These curves indicate the typical variation in spectral response caused by the deposition of cesium and oxygen. By the way of comparing and analyzing those curves, some valuable data obtained which are helpful in investigating the mechanism of the activation.