Speaker
Description
Photocathodes based on GaAs are used as photo-electron sources to supply spin-polarized, high-current electron beams for accelerator applications. A thin surface layer, typically comprised of Cs and an oxidant, needs to be applied to such photocathodes during an activation process in order achieve negative electron affinity (NEA). The NEA layer and the associated quantum efficiency (QE) deteriorates over time. This decay is characterized by the so-called lifetime, a crucial parameter for photo-electron source operation. An increase of surface layer durability and, hence, lifetime by adding Li during activation has been successfully shown in previous studies.
Recently, lifetime studies of bulk GaAs photocathodes activated with Cs, O$_2$, and Li have been conducted using the activation chamber of the Photo-CATCH setup at the Institut für Kernphysik of Technische Universität Darmstadt. We will present the results of these measurements as well as additional measurements planned in the future.
*Work supported by DFG (GRK 2128 “AccelencE”, project number 264883531)
