O. Apsimon
A5051851592- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Particle Detector Development and Performance
- Plasma Diagnostics and Applications
- Particle physics theoretical and experimental studies
- Dust and Plasma Wave Phenomena
- Laser-induced spectroscopy and plasma
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Radiation Therapy and Dosimetry
- Astrophysics and Cosmic Phenomena
- Laser-Matter Interactions and Applications
- Solar and Space Plasma Dynamics
- Diamond and Carbon-based Materials Research
- Radiation Detection and Scintillator Technologies
- Atomic and Molecular Physics
- Plasma and Flow Control in Aerodynamics
- Photocathodes and Microchannel Plates
- Lightning and Electromagnetic Phenomena
- Photonic and Optical Devices
- Electrical Fault Detection and Protection
- Gamma-ray bursts and supernovae
- Terahertz technology and applications
University of Manchester
2017-2025
Cockcroft Institute
2016-2025
University of Liverpool
2021-2023
Sci-Tech Daresbury
2017-2023
European Organization for Nuclear Research
2023
Campbell Collaboration
2020-2022
Lancaster University
2016-2021
Google (United States)
2019
High energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. In order to increase or reduce size accelerator, new acceleration schemes need be developed. Plasma wakefield acceleration, which electrons plasma are excited, leading strong electric fields, is one such promising novel technique. Pioneering experiments shown an intense laser pulse electron bunch traversing plasma, drives fields 10s...
We give direct experimental evidence for the observation of full transverse self-modulation a long, relativistic proton bunch propagating through dense plasma. The exits plasma with periodic density modulation resulting from radial wakefield effects. show that is seeded by ionization front created using an intense laser pulse copropagating bunch. extends over length following seed point. By varying one order magnitude, we frequency scales expected dependence on density, i.e., it equal to...
The seeded self-modulation of a relativistic, charged particle bunch in plasma is shown to grow both along the and plasma, resulting transverse wakefield amplitudes that far exceed initial seed values.
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,...
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...
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...
Wakefield wavelengths associated with solid-state plasmas greatly limit the accelerating length. An alternative approach employs 2D carbon-based nanomaterials, like graphene or carbon nanotubes (CNTs), configured into structured targets. These nanostructures are designed voids low-density regions to effectively reduce overall plasma density. This reduction enables use of longer-wavelength lasers and also extends wavelength acceleration In this study, we present, our knowledge, first...
This paper presents the design and experimental commissioning of a noninvasive electron bunch length monitor based on detection coherent Cherenkov diffraction radiation (ChDR). The measurement technique effectively eliminates influence bunch-by-bunch charge fluctuations, as each detector measures signal from same while mitigating impact position jitter measurements, providing potential real-time diagnostic tool with significant operational advantages. sensitivity measurements to both...
Abstract Recent nanotechnology advances enable fabrication of layered structures with controllable inter-layer gap, giving the ultra-violet (UV) lasers access to solid-state plasmas which can be used as medium for electron acceleration. By using a linearly polarized 3 fs-long laser pulse 100 nm wavelength and 10 $$^{21}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mn>21</mml:mn> </mml:msup> </mml:math> W/cm $$^2$$ <mml:mn>2</mml:mn> peak intensity,...
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.
This document provides detailed information on the status of Advanced and Novel Accelerators techniques describes steps that need to be envisaged for their implementation in future accelerators, particular high energy physics applications. It complements overview prepared update European Strategy particle physics, a description field. The scientific priorities community are described each technique acceleration able achieve accelerating gradient GeV~range or above. ALEGRO working group...
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...
Charged particle acceleration using solid-state nanostructures has attracted attention in recent years as a method of achieving ultra-high-gradient the TV/m domain. More concretely, metallic hollow could be suitable for through excitation wakefields by laser or high-intensity charged beam high-density plasma. For instance, due to their special channelling properties well optoelectronic and thermo-mechanical properties, carbon nanotubes an excellent medium this purpose. This article...
We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. show that wakefields' growth amplitude increase with increasing seed as well charge using maximum radius of distribution measured on screen downstream from externally injecting electrons measuring their final energy. Measurements agree trends predicted theory numerical simulations validate our understanding development self-modulation. Experiments...
Abstract In 2017, AWAKE demonstrated the seeded self-modulation (SSM) of a 400 GeV proton beam from Super Proton Synchrotron at CERN. The angular distribution protons deflected due to SSM is quantitative measure process, which agrees with simulations by two-dimensional (axisymmetric) particle-in-cell code LCODE about 5%. agreement achieved in population scans two selected plasma densities and scan longitudinal density gradient. reached only case wide enough simulation box (several...
The advanced wakefield experiment (AWAKE) at CERN is the first proton beam-driven plasma acceleration experiment. main goal of AWAKE RUN 1 was to demonstrate seeded self-modulation (SSM) beam and electron witness in wakefield. For experiment, a 10-meter-long Rubidium-vapor cell together with high-power laser for ionization used generate plasma. driven by 400 GeV/c extracted from super synchrotron (SPS), which undergoes process probe wakefields generated an S-band RF photo-cathode gun then...
Simulations of proton-driven plasma wakefield accelerators have demonstrated substantially higher accelerating gradients compared to conventional and the viability electrons energy frontier in a single stage. However, due strong intrinsic transverse fields varying both radially time, witness beam quality is still far from suitable for practical application future colliders. Here we demonstrate efficient acceleration wakefields hollow channel. In this regime, bunch positioned region with...
In this article, we briefly summarize the experiments performed during first Run of Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal AWAKE 1 (2013 - 2018) was to demonstrate that \unit[10-20]{MeV} electrons can be accelerated GeV-energies in a plasma wakefield driven by highly-relativistic self-modulated proton bunch. We describe experiment, outline measurement concept and present results. Last, our plans future.
We study experimentally the effect of linear plasma density gradients on self-modulation a 400\,GeV proton bunch. Results show that positive/negative gradient in/decreases number micro-bunches and relative charge per micro-bunch observed after 10\,m plasma. The measured modulation frequency also in/decreases. With largest positive we observe two frequencies in power spectrum. are consistent with changes wakefields' phase velocity due to adding slow during growth predicted by theory.
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...
Proton-driven plasma wakefield acceleration has been demonstrated in simulations to be capable of accelerating particles the energy frontier a single stage, but its potential is hindered by fact that currently available proton bunches are orders magnitude longer than wavelength. Fortunately, micro-bunching allows driving waves resonantly. In this paper, we propose using hollow channel for multiple bunch driven and demonstrate it enables operation nonlinear regime resonant excitation strong...
A plasma beam dump uses the collective oscillations of electrons to absorb kinetic energy a particle beam. In this paper, modified passive scheme is proposed using either gradient or stepped profile maintain higher decelerating compared with uniform plasma. The improvement result wavelength change preventing re-acceleration low particles. Particle-in-cell simulation results show that both and profiles can achieve improved loss for an electron bunch parameters routinely achieved in laser...
Staged acceleration, driven by terahertz (THz) frequency radiation pulses in a lattice with alternating orientation dielectric-lined waveguides and intervening matching optics, is shown to mitigate transverse emittance energy spread growth, opening route multistage THz linacs. Decomposition of the longitudinal field into multipolar components reveals quadrupole component strong radial dependence. As such, it induces correlation beam during acceleration due large variation electric radius...
Abstract High-brightness particle beams generated by advanced accelerator concepts have the potential to become an essential part of future technology. In particular, high-gradient accelerators can generate and rapidly accelerate relativistic energies. The rapid acceleration strong confining fields minimize irreversible detrimental effects beam brightness that occur at low energies, such as emittance growth or pulse elongation caused space charge forces. Due high accelerating gradients,...
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...