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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 9: Electron Accelerators and Particle Sources

AKBP 9.5: Vortrag

Mittwoch, 17. März 2021, 17:30–17:45, AKBPb

Preparation of phothocathodes with nitrogen triflouride — •Jennifer Groth — Johannes Gutenberg-Universität Mainz, Institut für Kernphysik, Mainz, Deutschland

In the new, energy-recovering superconducting accelerator MESA in Mainz, spin-polarized electrons are required in the P2 experiment. Here the requirements increase considerably compared to the photocathode for the spin-polarized electrons for the microtron in Mainz.

A very sensitive part of the photocathodes concerns the specially prepared surface. The surface, which has a negative electron affinity, is particularly sensitive to residual gases in vacuum and suffers from ion back bombardment due to the radiation generated. The negative electron affinity of the surface is achieved through a preparation with alkali metals and an oxidizing agent, in the most common case with cesium and oxygen. One aspect of surface preparation that is being pursued takes up the idea of working oxygen-free with nitrogen trifluoride and cesium. It has already been shown in other studies that this method delivers results that are as good as a preparation with oxygen and cesium with regard to the quantum yield.

The aim is to examine the advantages of an oxygen-free preparation, especially with regard to the influence on the evolution of spin polarization during the experiment.