Diagram of the AWAKE beam-line (Credits: Edda Gschwendtner, CERN)
Breakthrough results from the AWAKE project have just been published in the prestigious scientific journal ‘Physical Review Letters’, both of them at “editor’s suggestion”.
17 February 2019
Plasma cell in the AWAKE Tunnel (copyright CERN)
The first paper describes experimental evidence for seeded self-modulation of long bunches of protons in a rubidium plasma, using time-resolved Optical Transition Radiation (OTR) images taken with a streak camera, supported by beam core and beam halo images obtained at an imaging station with a scintillating screen.
The second paper reports on transverse self-modulation in a proton bunch, seeded by an intense laser pulse which co-propagates with the protons through a plasma. A linear variation of modulation frequency with plasma density is also observed, showing that the modulation and the plasma frequencies are equal, as expected.
These results are key to achieving the goal of using wakefields, created in a plasma and driven by long proton bunches, for accelerating electrons which are injected to follow these wakefields. Ultimately this technique could achieve extremely high accelerations up to hundreds of GeV or even to TeV in short distances, for the benefit of high-energy physics.
AWAKE is the Advanced Wakefield Experiment, hosted at CERN, which is a collaborative project with significant contributions from the UK through the STFC-funded AWAKE-UK project.
Professor Carsten Welsch from the Cockcroft Institute and scientific project manager of AWAKE-UK said: “These are fantastic results from the AWAKE experiment. They open up a pathways for an entirely new technique for particle beam acceleration which can enable new types of experiments and applications.”
‘Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch’, M. Turner et al., PHYSICAL REVIEW LETTERS 122, 054801 (2019) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.054801
‘Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities’, K. Rieger et al., PHYSICAL REVIEW LETTERS 122, 054802 (2019) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.054802