Experimental Materials Research for Photoelectron Sources

This project will focus on the fabrication and testing of metal-semiconductor materials for photocathode applications, to identify materials and preparation techniques that optimise material performance. The project has two strands to the research programme, using;

- laboratory-based instrumentation to prepare, fabricate and characterise materials suitable for photocathodes, including the commissioning of a new deposition system to growth thin alkali antimonide/telluride layers.

- existing metal photocathode preparation facility and the new growth system to produce cathodes for testing in the VELA electron injector, using the extensive suite of machine diagnostics to measure transverse and longitudinal beam properties.

The student will join ASTeC's Accelerator Physics group at Daresbury National Laboratory for the duration of the research. This project is an extension of previous research undertaken in ASTeC which led to significant results both in electrostatic modelling of the Transverse Energy Spread Spectrometer (TESS) and measurement of transverse and longitudinal energy distributions of photocathode materials.

In the first year of the project the student will familiarise themselves with the existing surface analysis equipment and contribute to the commissioning of the new alkali antimonide/telluride growth facility. Complementary data will also be collected using the TESS instrument. In the latter part of the project photocathodes will be produced for testing in the VELA accelerator with pre- and post-testing characterisation. In-accelerator testing will be carried out using the existing suite of diagnostics, including the spectrometer line for measuring energy and energy spread, quad scans for emittance measurements and the transverse deflecting cavity for bunch length (and hence response time) characterisation.

The proposed project has the capacity to generate considerable impact. The data generated will provide invaluable input to support VELA/CLARA accelerator operations, in particular contributing to the establishment of stable and reliable operating conditions. In addition, the results will contribute to the on-going specification of the electron injector for the proposed UK XFEL and FCC prototype, developing the expertise and reducing the risk associated with this critical sub-system of the accelerator. Ultimately, the work will contribute to the ongoing international effort to understand and improve photocathode performance, which is important for both FEL applications and High Energy Physics machines.