A step towards mini accelerators for widespread use

UK scientists and engineers, working at CERN, have helped achieve a world first which could enable widespread use of particle accelerators in labs and hospitals around the world.

In a paper published in journal Nature the ‘AWAKE’ collaboration reports the successful acceleration of electrons using a wave generated by protons zipping through plasma. The acceleration is 40 times higher than that so far recorded using conventional accelerator technologies in CERN’s Large Hadron Collider, meaning that the use of plasma waves or so-called wakefields may offer a new way to build small-size, affordable, high-energy particle accelerators.

AWAKE-UK Scientific Project Manager, Professor Carsten Welsch, commented: "This breakthrough result shows, for the first time, that proton-driven electron beam acceleration offers a promising pathway towards the highest energy beams provided by a very compact accelerator. This has the potential to enable entirely new particle physics experiments.”

In May this year the AWAKE collaboration successfully accelerated electrons in plasma for the first time. Electrons injected into AWAKE at relatively low energies of around 19 MeV ‘rode’ the plasma wave and were accelerated by a factor of around 100; to an energy of almost 2 GeV over a length of 10 metres.

Current state-of-the-art particle accelerator technologies, considered for the next generation of electron accelerators, promise gradients in the range of just 30–100 million volts per metre. These represent today’s most advanced technology for the overall distance over which acceleration can be sustained, on the one hand, and the intensity and quality of accelerated beams, on the other – two important factors required for high-energy physics experiments. However, they have reached their limit. The next steps of AWAKE, which aims to achieve gradients of 1,000 MV/m, include addressing these additional requirements.

While previous experiments have relied on using electrons or lasers to drive the wake, AWAKE is the first to use protons. “Drive beams of protons penetrate deeper into the plasma than drive beams of electrons and lasers,” said Allen Caldwell, Spokesperson of the AWAKE collaboration. “Therefore, wakefield accelerators relying on protons for their drive beams can accelerate electrons for a greater distance, consequently allowing them to attain higher energies.”