Beam Dynamics of CBETA: Developing a Prototype Energy-Recovery Linac for Future Colliders and Light Sources

EMMA (Electron Machine with Many Applications) was the world’s first non-scaling FFAG and was built and operated at Daresbury Laboratory. EMMA successfully demonstrated a new type of acceleration as well as a new type of beam transport. EMMA used the ALICE (Accelerators and Lasers In Combined Experiments) as an injector. ALICE was an energy recovery linac (ERL) accelerator.

A new project is currently underway at Cornell University in the U.S., in collaboration with Brookhaven National Laboratory (BNL). This project combines the non-scaling FFAG concept demonstrated on EMMA together with the idea of energy recovery into one accelerator called CBETA (Cornell-BNL ERL Test Accelerator). CBETA is a prototype for the electron transport part of an electron-ion collider (EIC) and it uses recirculation to increase the electron beam energy by a factor of four. Because the recirculation uses the same non-scaling FFAG style transport that was used on EMMA, all four energy trajectories fit into a single beampipe.

This novel style of recirculation leads to some extremely interesting options for the next phases that an accelerator like CBETA could have. In particular, if the four different energies can easily be separated and the bunch quality preserved, then it should be possible to run four different energies through free electron lasers (FELs) with four output wavelengths. Furthermore, the four different FELs would be perfectly synchronised, thus facilitating pump-probe experiments with biological samples, utilising concepts developed by our group over previous years.

The PhD student would be expected to explore the various possibilities for improving the output bunch as well as forming a central part, as far as a possible CBETA upgrade is concerned, of the wider collaboration outlined below. The student would also be expected to have an active role in the commissioning of the first phase of CBETA. The project results will also inform the ongoing design studies for the future national UK free-electron laser facility (UK-FEL), and may determine its baseline configuration.

This project has simulation, analytical and experimental aspects to it. The focus of the project will be determined according to the student’s interest and aptitude.

The successful candidate will have or expect to obtain a first or upper second-class degree or equivalent (e.g. MPhys, MSci) in physics. Experience of accelerator physics, particle physics or computational physics is desirable but not essential.