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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 7: Particle Sources

AKBP 7.2: Vortrag

Dienstag, 29. März 2022, 16:15–16:30, AKBP-H13

Improved Performance of GaAs photo-cathodes activated by Cs, O2 and Li — •Maximilian Herbert, Joachim Enders, Markus Engart, Yuliya Fritzsche, Julian Schulze, and Vincent Wende — Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt

Photo-cathodes based on GaAs can be characterized mainly by two parameters: quantum efficiency η and lifetime τ. The former describes the photo-emission efficiency, while the latter is an indicator for the decay of the surface layer required to achieve negative electron affinity (NEA) for GaAs. This layer typically consists of Cs in combination with an oxidant. Previous studies have suggested that the addition of Li to this layer can significantly increase cathode performance by boosting both η and τ. At the Institut für Kernphysik of the Technische Universität Darmstadt, a dedicated test stand for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen (Photo-CATCH) is available for GaAs photocathode research. This contribution will present recent performance studies at Photo-CATCH of bulk GaAs photo-cathodes activated with Cs, O2, and Li in comparison to activations using Cs and O2 only. An increase in τ by a factor of 7 has been observed without significant reduction of η for Li-enhanced activation.