CHARACTERIZATION OF A SUPERCONDUCTING Pb PHOTOCATHODE IN A SRF GUN CAVITY

Photocathodes are a limiting factor for the next generation of ultra-high brightness photoinjector driven accelerators. We studied the behavior of a superconducting Pb cathode in the cryogenic environment of a superconducting RF gun cavity related to the quantum efficiency (QE), its spatial distribution and the work function. The cathode surface contaminations can modify the performance of the photocathodeas well as the gun cavity. We discuss the possibilities to remove these contaminants.