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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 1: Particle Sources
AKBP 1.3: Vortrag
Montag, 16. März 2020, 15:30–15:45, MOL 213
Improved Performance of GaAs photo-cathodes activated by Cs, Li and NF3* — •Maximilian Herbert1, Joachim Enders1, Matthew Poelker2, and Carlos Hernandez-Garcia2 — 1Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany — 2Thomas Jefferson National Accelerator Facility, Newport News, VA, United States of America
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. Recently, first lifetime studies of bulk GaAs photo-cathodes activated with Cs, NF3, and Li have been conducted using the photo-electron gun of the Upgraded Injector Test Facility (UITF) at the Thomas Jefferson National Accelerator Facility (JLab), extracting beam currents of up to 100 µA. We will present the results of these measurements as well as planned measurements at the Institut für Kernphysik at Technische Universität Darmstadt.
*Work supported by DFG (GRK 2128 "AccelencE"), BMBF (05H18RDRB1), and through the Helmholtz Graduate School for Hadron and Ion Research for FAIR.