Proposal for continuation of the Front End Test Stand

Protons, subatomic particles that are one of the building blocks of matter, can be given large amounts of energy by passing through a machine called a proton accelerator. Such high energy protons can be used in a wide variety of applications, from the production of radioisotopes for the treatment of disease, to the investigation of the structure of matter that benefits both industry and science. The first step in any proton accelerator complex is the so-called proton driver. The Front End Test Stand (FETS), being built at the Rutherford Appleton Laboratory (RAL) in the UK, is a project to create a new state-of-the-art proton driver that will be needed in order to provide proton accelerators with more intense, higher energy beams for future applications.

The FETS produces a beam of negatively-charged hydrogen ions that is chopped up into smaller bunches. This chopping is needed in order to make it safer and easier to accelerate the protons that are obtained by removing the electrons from the hydrogen ion beam. The FETS collaboration involves a dedicated team of scientists and engineers from the UK, and has stimulated collaborations with leading international accelerator institutes such as CERN, FNAL, ESS and CNS.

In this proposal, we seek to complete the construction of the FETS in a timely manner. The hydrogen ion source and initial beam focusing components have already been built and successfully commissioned. The remaining work is to install, test and commission the accelerating structures and chopper systems, and to evaluate the performace of the complete test stand. Upon successful completion of this project, the FETS can be used as a proton driver for further developments in proton accelerator systems for a wide range of applications in industry, medicine and science.

The Front End Test Stand (FETS) under construction at the Rutherford Appleton Laboratory (RAL) is the UK's contribution to research into the next generation of High Power Proton Accelerators (HPPAs). HPPAs are an essential part of any future Spallation Neutron Source, Neutrino Factory, Muon Collider, Accelerator Driven Sub-critical System, Waste Transmuter etc. FETS will demonstrate a high quality, high intensity, chopped H-minus beam and is a collaboration between RAL, Imperial College, the Universities of Warwick and London (Royal Holloway) in the UK, as well as the Universidad del Pais Vasco and ESS-Bilbao in Spain.

Beam chopping will be an important feature of the next generation of HPPAs. The requirement to minimise the need for remote handling of accelerator components dictates that beam loss in future machines must be kept to levels comparable to those of current facilities in order to avoid activation. With beam powers an order of magnitude or more than those currently achieved, fractional beam loss must necessarily be reduced by a similar factor. The FETS project will be able to demonstrate the techology required for beam chopping in future HPPAs.

Originally conceived simply as a chopper beam test, the FETS has since expanded its objectives to become a generic test stand for technologies related to the front end of several proposed projects which require a high-power proton driver, as mentioned above. A secondary objective of FETS was to encourage the study of accelerator technology by a new generation of accelerator engineers and physicists in UK universities. The quality of the work being produced by the (mostly) young team working on FETS is testament to the success of this objective. FETS has also resulted in a fruitful collaboration between RAL/ISIS and the ESS-Bilbao project in Spain. The exchange of ideas, experience and hardware is proving extremely beneficial to both sides. The work undertaken has contributed to the UK's continuing international reputation as a centre of excellence and has stimulated collaborations with leading international accelerator institutes such as CERN, FNAL, ESS and CNS.