Dortmund 2021 – wissenschaftliches Programm

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 9: Electron Accelerators and Particle Sources

AKBP 9.7: Vortrag

Mittwoch, 17. März 2021, 18:00–18:15, AKBPb

Automated activation procedures for GaAs-photocathodes — •Markus Engart, Joachim Enders, Yuliya Fritzsche, Maximilian Herbert, Manuel Steinhorst, and Vincent Wende — Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstr. 9, 64289 Darmstadt

Gallium-arsenide-based photocathodes are used for a variety of applications. In particular, they serve in sources of polarized electrons. The source performance depends on the quantum efficiency and lifetimes of the photocathodes, usually activated to negative electron affinity using an alkali metal and an oxidant. Good reproducibility of the activation is desired in order to ensure stable and simple operation of such sources. Hence, an automation of this process is envisaged.

The Photo-CATCH (Photo-Cathode Activation, Test and Cleaning using Atomic Hydrogen) test stand at TU Darmstadt is used for experiments with un-/spinpolarized electrons with energies up to 60 keV. This contribution presents the results of experiments with automated activations following the co-deposition of caesium and oxygen using empirically determined values for the the different activation stages. Results show typical variations in the achieved quantum efficiency of about 20%.

Supported in part by BMBF (05H18RDRB1) and DFG (GRK 2128 AccelencE, project number 264883531).