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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 16: Posters

AKBP 16.1: Poster

Donnerstag, 19. März 2020, 16:30–18:00, P1C

Activation Studies of GaAs Photo-Cathodes at TU Darmstadt* — •Vincent Wende, Joachim Enders, Markus Engart, Yuliya Fritzsche, and Maximilian Herbert — Institut für Kernphysik, Technische Universität Darmstadt, Germany

Spin-polarized electron sources based on GaAs photo-cathodes can be used to supply high-current electron beams for various applications. A thin layer covering the GaAs surface - typically consisting of Cs in combination with an oxidant - is required to achieve negative electron affinity (NEA). The aim of this process is to reach high quantum efficiency η and long surface layer lifetime τ to ensure smooth and sustained operation of a photo-gun in an accelerator. Both parameters strongly depend on the activation procedure. Hence, an optimization of this process is desired. For this purpose, a dedicated test stand for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen Photo-CATCH has been set up at the Institut für Kernphysik at TU Darmstadt [1]. This setup consists of a vacuum system for photo-cathode activation and cleaning, as well as a DC photo-gun test chamber with adjacent 60 keV beamline. Results of ongoing experiments and options for automatizing the activation procedure will be discussed.
[1] N. Kurichiyanil et al., J. Instr. 14, P08025 (2019)
*Work supported by the Deutsche Forschungsgemeinschaft (GRK 2128 "AccelencE") and BMBF (05H18RDRB1)