SMuK 2023 – scientific programme
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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 1: Particle and Photon Sources
AKBP 1.2: Talk
Monday, March 20, 2023, 16:15–16:30, CHE/0183
Automated Activation Procedure for GaAs Photocathodes at Photo-CATCH* — •Maximilian Herbert, Tobias Eggert, Joachim Enders, Markus Engart, Yuliya Fritzsche, and Vincent Wende — Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Schlossgartenstr. 9, 64289 Darmstadt
Photo-electron sources using GaAs-based photocathodes are used to provide high-brightness and high-current beams of spin-polarized electrons for accelerator applications such as ERLs. Such cathodes require a thin surface layer consisting of Cs and an oxidant in order to achieve negative electron affinity (NEA) for efficient photoemission. The layer is deposited during a so-called activation procedure, whose performance greatly influences the resulting quantum efficiency η of the photocathode and robustness of the layer. An automatization of the activation procedure could simplify and accelerate this process, indipendent from expert input, for operational use in an accelerator. At TU Darmstadt, the dedicated test stand Photo-CATCH is available for GaAs photocathode research. The components of its activation chamber are remote-controlled using EPICS. This contribution will present recent proof-of-principle studies of a basic automated activation procedure at Photo-CATCH. Using a co-deposition scheme with Cs and O2, several automated activations have been performed. A good reproducibility of η has been observed, with a slight reduction in mean η compared to manual activation.
*Work supported by DFG (GRK 2128 AccelencE, project number 264883531) and BMBF (05H18RDRB1)