• C. Shonaka, H. Higaki, K. Ito, D. Kubo, M. Kuriki, H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• T. Konomi, T. Nakanishi, S. Okumi, M. Yamamoto
  Nagoya University, Nagoya

High brightness electron source is a key technology for future projects based on advanced accelerators. Although GaAs photo-cathode is very attractive because it can generate highly polarized and extremely high brightness electron beam, the limited operational life time is a technical issue. In Hiroshima University, a photo-cathode test bench is implemented for various studies of GaAs photo-cathode. Super high vacuum, 9E-9Pa, was achieved and the cathode was successfully activated by processes of heat cleaning technique and the alternate evaporation of Cs and oxygen. The quantum efficiency and its lifetime were investigated as a function of cathode temperature, simulating temperature rise by the high power cathode drive laser. Wavelength dependence was also investigated.