Dortmund 2021 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 9: Electron Accelerators and Particle Sources

AKBP 9.3: Talk

Wednesday, March 17, 2021, 17:00–17:15, AKBPb

Development of a GaAs-based photo-electron source with cryogenic components — •Tobias Eggert, Joachim Enders, and Yuliya Fritsche — Institut für Kernphysik, TU Darmstadt, Germany

Polarized electron beams can be generated using the internal photo-effect with GaAs as a photocathode. However, a negative-electron-affinity (NEA) coating consisting of a CsO layer, is necessary when using GaAs. This layer limits the operational lifetime as it gets corroded by oxygen and destroyed by ionized residual gas molecules hitting the surface. The latter is called ion back-bombardment (IBB) and one of the main lifetime limiting factors. Improving the vacuum conditions near the cathode surface is expected to reduce IBB and increase the lifetime. At the Photo-CATCH test facility in Darmstadt, an electron source is developed which uses cryocooling of a sub-volume around the cathode. In addition to the sub-volume, the cathode itself gets cooled.

This project is supported by DFG (GRK 2128) and BMBF (05H18RDRB1).