A5060443976- Particle Accelerators and Free-Electron Lasers
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Particle Detector Development and Performance
- Gyrotron and Vacuum Electronics Research
- Pulsed Power Technology Applications
- Plasma Diagnostics and Applications
- Ion-surface interactions and analysis
- Particle physics theoretical and experimental studies
- Electron and X-Ray Spectroscopy Techniques
- Neutrino Physics Research
- Radiation Therapy and Dosimetry
- Atomic and Molecular Physics
University of Oxford
2021-2025
European Organization for Nuclear Research
2024
Campbell Collaboration
2022
Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use high energy protons drive wakefields in plasma has been demonstrated during Run 1 AWAKE programme at CERN. Protons 400 GeV drove that accelerated electrons 2 under 10 m plasma. collaboration now embarking on with main aims demonstrate stable accelerating gradients 0.5–1 GV/m, preserve emittance electron bunches and develop sources scalable 100s metres beyond. By end 2, scheme should...
We show in experiments that a long, underdense, relativistic proton bunch propagating plasma undergoes the oblique instability, which we observe as filamentation. determine threshold value for ratio between transverse size and skin depth instability to occur. At threshold, outcome of experiment alternates filamentation self-modulation (evidenced by longitudinal modulation into microbunches). Time-resolved images density distribution reveal grows an observable level late along bunch,...
Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven short, misaligned preceding bunch. Hosing develops the plane misalignment, self-modulation perpendicular plane, at frequencies close to electron frequency, and are reproducible. Development depends on misalignment direction, its growth extent proton charge. Results have main characteristics theoretical model, relevant other plasma-based accelerators represent first characterization...
A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton can be seeded by wakefields driven preceding electron bunch. timing reproducibility and control are at level small fraction modulation period. With this seeding method, we independently amplitude seed with charge growth rate Seeding leads larger than instability case.
We show experimentally that an effect of motion ions, observed in a plasma-based accelerator, depends inversely on the plasma ion mass. The appears within single wakefield event and manifests itself as bunch tail, occurring only when sufficient ions suppresses wakefields. Wakefields are driven resonantly by multiple bunches, simulation results indicate ponderomotive force causes ions. In this case, is also expected to depend amplitude wakefields, confirmed through variations drive charge.
We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of long proton bunch in plasma. show experimentally that, with sufficient amplitude [$\ensuremath{\ge}(4.1\ifmmode\pm\else\textpm\fi{}0.4)\text{ }\text{ }\mathrm{MV}/\mathrm{m}$], phase modulation along is reproducible from event event, 3%--7% (of $2\ensuremath{\pi}$) rms variations all bunch. The not lower amplitudes. observe transition between these two regimes. Phase...
Self-modulation is a beam–plasma instability that useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing ratio between initial transverse size of bunch and depth, occurs later along bunch, or not at all, over fixed length because amplitude decreases. show cases for which self-modulation does develop, we introduce simple model discussing conditions it would occur after any length. Changing...
We exploit the coherent emission of Cherenkov diffraction radiation (ChDR) by a relativistic electron beam to sense its position even in presence other particle beams. ChDR is produced alumina inserts embedded vacuum chamber walls and recorded narrow band centered at 30 GHz. This nontrivial solution has been implemented for plasma wakefield accelerators, where be sensed can copropagate with another high-energy proton that generates wakefield. In addition, variance most existing detectors,...
We present numerical simulations and experimental results of the self-modulation a long proton bunch in plasma with linear density gradients along beam path. Simulation agree reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)]: negative gradients, charge modulated is lower than positive gradients. In addition, modulation frequency varies gradient. show that dephasing wakefields respect to relativistic protons main cause for loss charge. The...
Abstract Cherenkov diffraction radiation is generated when a charged particle beam passes in close proximity to dielectric target, and currently being studied developed for various non-invasive instrumentation applications at CERN. One such instrument position monitor (BPM) composed of four cylindrical inserts. A challenge using the conventional stretched wire technique characterize BPM up high frequencies coupling unwanted higher order modes (HOM) into inserts that are dielectric-loaded...
The vertical plane transverse emittance of accelerated electron bunches at the AWAKE experiment CERN has been determined, using three different methods data analysis. This is a proof-of-principle measurement existing spectrometer to validate technique. Large values geometric emittance, compared that injection beam, are observed ($\sim \SI{0.5}{\milli\metre\milli\radian}$ with $\sim \SI{0.08}{\milli\metre\milli\radian}$), which in line expectations growth arising from plasma density ramps and...
A precise characterization of the incoming proton bunch parameters is required to accurately simulate self-modulation process in Advanced Wakefield Experiment (AWAKE). This paper presents an analysis bunches used later stages AWAKE Run 1 data-taking period. The transverse structure observed at multiple positions along beamline using scintillating or optical transition radiation screens. a model that describes dimensions and divergence are fitted represent data Bayesian inference. tested on...
Abstract The Advanced Proton Driven Plasma Wakefield Experiment (AWAKE) at CERN uses 6 cm long proton bunches extracted from the Super Synchrotron (SPS) 400 GeV beam energy to drive high gradient plasma wakefields for acceleration of electron 2 within a 10 m length. Knowledge and control position both copropagating beams is crucial operation experiment. Whilst current monitoring system AWAKE can be used in absence beam, bunch signal dominates when particle are present simultaneously. A new...
Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. Use high energy protons drive wakefields in plasma has been demonstrated during Run 1 AWAKE programme at CERN. Protons 400 GeV drove that accelerated electrons 2 under 10 m plasma. The collaboration now embarking on with main aims demonstrate stable accelerating gradients 0.5-1 GV/m, preserve emittance electron bunches and develop sources scalable 100s metres beyond. By end 2, scheme should...