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  • Journal article
    Consoli F, De Angelis R, Robinson TS, Giltrap S, Hicks GS, Ditter EJ, Ettlinger OC, Najmudin Z, Notley M, Smith RAet al., 2019,

    Generation of intense quasi-electrostatic fields due to deposition of particles accelerated by petawatt-range laser-matter interactions

    , Scientific Reports, Vol: 9, ISSN: 2045-2322

    We demonstrate here for the first time that charge emitted by laser-target interactions at petawatt peak-powers can be efficiently deposited on a capacitor-collector structure far away from the target and lead to the rapid (tens of nanoseconds) generation of large quasi-static electric fields over wide (tens-of-centimeters scale-length) regions, with intensities much higher than common ElectroMagnetic Pulses (EMPs) generated by the same experiment in the same position. A good agreement was obtained between measurements from a classical field-probe and calculations based on particle-flux measurements from a Thomson spectrometer. Proof-of-principle particle-in-cell simulations reproduced the measurements of field evolution in time, giving a useful insight into the charging process, generation and distribution of fields. The understanding of this charging phenomenon and of the related intense fields, which can reach the MV/m order and in specific configurations might also exceed it, is very important for present and future facilities studying laser-plasma-acceleration and inertial-confinement-fusion, but also for application to the conditioning of accelerated charged-particles, the generation of intense electric and magnetic fields and many other multidisciplinary high-power laser-driven processes.

  • Conference paper
    McIlvenny A, Doria D, Romagnani L, Ahmed H, Martin P, WIlliamson SDR, Ditter EJ, Ettlinger O, Hicks GS, McKenna P, Najmudin Z, Neely D, Kar S, Borghesi Met al., 2019,

    Absolute calibration of microchannel plate detector for carbon ions up to 250 MeV

    , 5th International Conference on Frontiers in Diagnostics Technologies, Publisher: IOP PUBLISHING LTD, ISSN: 1748-0221
  • Journal article
    King M, Butler NMH, Wilson R, Capdessus R, Grays RJ, Powell HW, Dance RJ, Padda H, Gonzalez-Izquierdo B, Rusby DR, Dover NP, Hicks GS, Ettlinger OC, Scullion C, Carroll DC, Najmudin Z, Borghesi M, Neely D, McKenna Pet al., 2019,

    Role of magnetic field evolution on filamentary structure formation in intense laser-foil interactions

  • Journal article
    Papp D, Wood JC, Gruson V, Bionta M, Gruse J-N, Cormier E, Najmudin Z, Legare F, Kamperidis Cet al., 2018,

    Laser wakefield acceleration with high-power, few-cycle mid-IR lasers

  • Journal article
    Warwick JR, Alejo A, Dzelzainis T, Schumaker W, Doria D, Romagnani L, Poder K, Cole JM, Yeung M, Krushelnick K, Mangles SPD, Najmudin Z, Samarin GM, Symes D, Thomas AGR, Borghesi M, Sarri Get al., 2018,

    General features of experiments on the dynamics of laser-driven electron-positron beams

    , Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 909, Pages: 95-101, ISSN: 0168-9002

    The experimental study of the dynamics of neutral electron–positron beams is an emerging area of research, enabled by the recent results on the generation of this exotic state of matter in the laboratory. Electron–positron beams and plasmas are believed to play a major role in the dynamics of extreme astrophysical objects such as supermassive black holes and pulsars. For instance, they are believed to be the main constituents of a large number of astrophysical jets, and they have been proposed to significantly contribute to the emission of gamma-ray bursts and their afterglow. However, despite extensive numerical modelling and indirect astrophysical observations, a detailed experimental characterisation of the dynamics of these objects is still at its infancy. Here, we will report on some of the general features of experiments studying the dynamics of electron–positron beams in a fully laser-driven setup.

  • Journal article
    Behm KT, Cole JM, Joglekar AS, Gerstmayr E, Wood JC, Baird CD, Blackburn TG, Duff M, Harvey C, Ilderton A, Kuschel S, Mangles SPD, Marklund M, McKenna P, Murphy CD, Najmudin Z, Poder K, Ridgers CP, Sarri G, Samarin GM, Symes D, Warwick J, Zepf M, Krushelnick K, Thomas AGRet al., 2018,

    A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV

  • Journal article
    Krushelnick K, Dangor AE, Kaluza M, Mangles SPD, Murphy CD, Najmudin Z, Thomas AGRet al., 2018,

    Observation of anomalous side-scattering in laser waketield accelerators

    , LASER AND PARTICLE BEAMS, Vol: 36, Pages: 391-395, ISSN: 0263-0346
  • Journal article
    Wood JC, Chapman DJ, Poder K, Lopes NC, Rutherford ME, White TG, Albert F, Behm KT, Booth N, Bryant JSJ, Foster PS, Glenzer S, Hill E, Krushelnick K, Najmudin Z, Pollock BB, Rose S, Schumaker W, Scott RHH, Sherlock M, Thomas AGR, Zhao Z, Eakins D, Mangles SPDet al., 2018,

    Ultrafast imaging of laser driven shock waves using Betatron x-rays from a laser Wakefield accelerator

    , Scientific Reports, Vol: 8, ISSN: 2045-2322

    Betatron radiation from laser wakefield accelerators is an ultrashort pulsedsource of hard, synchrotron-like x-ray radiation. It emanates from a centimetrescale plasma accelerator producing GeV level electron beams. In recent yearsbetatron radiation has been developed as a unique source capable of producinghigh resolution x-ray images in compact geometries. However, until now, theshort pulse nature of this radiation has not been exploited. This reportdetails the first experiment to utilise betatron radiation to image a rapidlyevolving phenomenon by using it to radiograph a laser driven shock wave in asilicon target. The spatial resolution of the image is comparable to what hasbeen achieved in similar experiments at conventional synchrotron light sources.The intrinsic temporal resolution of betatron radiation is below 100 fs,indicating that significantly faster processes could be probed in futurewithout compromising spatial resolution. Quantitative measurements of the shockvelocity and material density were made from the radiographs recorded duringshock compression and were consistent with the established shock response ofsilicon, as determined with traditional velocimetry approaches. This suggeststhat future compact betatron imaging beamlines could be useful in the imagingand diagnosis of high-energy-density physics experiments.

  • Journal article
    Schumaker W, Liang T, Clarke R, Cole JM, Grittani G, Kuschel S, Mangles SPD, Najmudin Z, Poder K, Sarri G, Symes D, Thomas AGR, Vargas M, Zepf M, Krushelnick Ket al., 2018,

    Making pions with laser light

    , NEW JOURNAL OF PHYSICS, Vol: 20, ISSN: 1367-2630
  • Journal article
    Poder K, Tamburini M, Sarri G, Di Piazza A, Kuschel S, Baird CD, Behm K, Bohlen S, Cole JM, Corvan J, Duff M, Gerstmayr E, Keitel CH, Krushelnick K, Mangles SPD, McKenna P, Murphy CD, Najmudin Z, Ridgers CP, Samarin GM, Symes DR, Thomas AGR, Warwick J, Zepf Met al., 2018,

    Experimental signatures of the quantum nature of radiation reaction in the field of an ultraintense laser

    , Physical Review X, Vol: 8, ISSN: 2160-3308

    The description of the dynamics of an electron in an external electromagnetic field of arbitrary intensity is one of the most fundamental outstanding problems in electrodynamics. Remarkably, to date, there is no unanimously accepted theoretical solution for ultrahigh intensities and little or no experimental data. The basic challenge is the inclusion of the self-interaction of the electron with the field emitted by the electron itself—the so-called radiation reaction force. We report here on the experimental evidence of strong radiation reaction, in an all-optical experiment, during the propagation of highly relativistic electrons (maximum energy exceeding 2 GeV) through the field of an ultraintense laser (peak intensity of 4×1020  W/cm2). In their own rest frame, the highest-energy electrons experience an electric field as high as one quarter of the critical field of quantum electrodynamics and are seen to lose up to 30% of their kinetic energy during the propagation through the laser field. The experimental data show signatures of quantum effects in the electron dynamics in the external laser field, potentially showing departures from the constant cross field approximation.

  • Journal article
    Streeter M, Kneip S, Bloom M, Bendoyro RA, Chekhlov O, Dangor AE, Doepp A, Hooker CJ, Holloway J, Jiang J, Lopes N, Nakamura H, Norreys PA, Palmer C, Rajeev PP, Schreiber J, Symes D, Wing M, Mangles SPD, Najmudin Zet al., 2018,

    Observation of laser power amplification in a self-injecting laser wakefield accelerator

    , Physical Review Letters, Vol: 120, Pages: 254801-1-254801-6, ISSN: 0031-9007

    We report on the depletion and power ampli cation of the driving laser pulse in a strongly-drivenlaser wake eld accelerator. Simultaneous measurement of the transmitted pulse energy and temporalshape indicate an increase in peak power from 18711 TW to a maximum of 31812 TW after13 mm of propagation in plasma density of 0:91018cm3. The power ampli cation is correlatedwith the injection and acceleration of electrons in the non-linear wake eld. This process is modeledby including localized redshift and subsequent group delay dispersion at the laser pulse front.

  • Journal article
    Cole JM, Symes DR, Lopes NC, Wood JC, Poder K, Alatabi S, Botchway SW, Foster PS, Gratton S, Johnson S, Kamperidis C, Kononenko O, De lazzari M, Palmer CAJ, Rusby D, Sanderson J, Sandholzer M, Sarri G, Szoke-Kovacs Z, Teboul L, Thompson JM, Warwick JR, Westerberg H, Hill MA, Norris DP, Mangles SPD, Najmudin Zet al., 2018,

    High-resolution mu CT of a mouse embryo using a compact laser-driven X-ray betatron source

  • Journal article
    Streeter M, Dann S, Scott JDE, Baird C, Murphy CD, Eardley S, Smith R, Rozario S, Gruse J, Mangles SPD, Najmudin Z, Tata S, Krishnamurthy M, Rahul SV, Hazra D, Pourmoussavi P, Osterhoff J, Hah J, Bourgeois N, Thornton C, Gregory CD, Hooker CJ, Checkhlov O, Hawkes SJ, Parry B, Marshall V, Tang Y, Springate E, Rajeev PP, Thomas AGR, Symes Det al., 2018,

    Temporal feedback control of high-intensity laser pulses to optimize ultrafast heating of atomic clusters

    , Applied Physics Letters, Vol: 112, Pages: 244101-1-244101-5, ISSN: 1077-3118

    We describe how active feedback routines can be applied at limited repetition rate (5 Hz) to optimize high-power (P>10 TW) laser interactions with clustered gases. Optimization of x-ray production from anargon cluster jet, using a genetic algorithm, approximately doubled the measured energy through temporalmodification of the 150 mJ driving laser pulse. This approach achieved an increased radiation yield throughexploration of a multi-dimensional parameter space, without requiring detailedaprioriknowledge of thecomplex cluster dynamics. The optimized laser pulses exhibited a slow rising edge to the intensity profile,which enhanced the laser energy coupling into the cluster medium, compared to the optimally compressedFWHM pulse (40 fs). Our work suggests that this technique can be more widely utilized for control of intensepulsed secondary radiation from petawatt-class laser systems.

  • Journal article
    Yu JQ, Hu RH, Gong Z, Ting A, Najmudin Z, Wu D, Lu HY, Ma WJ, Yan XQet al., 2018,

    The generation of collimated gamma-ray pulse from the interaction between 10 PW laser and a narrow tube target

    , APPLIED PHYSICS LETTERS, Vol: 112, ISSN: 0003-6951
  • Journal article
    McGuffey C, Schumaker W, Matsuoka T, Chvykov V, Dollar F, Kalintchenko G, Kneip S, Najmudin Z, Mangles SPD, Vargas M, Yanovsky V, Maksimchuk A, Thomas AGR, Krushelnick Ket al., 2018,

    On the properties of synchrotron-like X-ray emission from laser wakefield accelerated electron beams

    , PHYSICS OF PLASMAS, Vol: 25, ISSN: 1070-664X
  • Conference paper
    Symes DR, Brenner CM, Rusby DR, Armstrong C, Thornton C, Bourgeois N, Katzir Y, Gregory CD, Neely D, Rajeev PP, Allott R, Wood JC, Lopes NC, Gruse JN, Cole JM, Mangles SPD, Najmudin Z, Murphy CD, Baird CD, Underwood C, Streeter MJV, Cipiccia Set al., 2018,

    Optimisation of compact laser driven accelerator X-ray sources for industrial imaging applications

    Compact laser-driven electron accelerators can produce coherent x-ray beams with high brightness, small source-size and femtosecond duration. We will discuss the suitability of these sources to address challenges in industrial imaging.

  • Journal article
    Cole JM, Behm KT, Blackburn TG, Wood JC, Baird CD, Duff MJ, Harvey C, Ilderton A, Joglekar AS, Krushelnik K, Kuschel S, Marklund M, McKenna P, Murphy CD, Poder K, Ridgers CP, Samarin GM, Sarri G, Symes DR, Thomas AGR, Warwick J, Zepf M, Najmudin Z, Mangles SPDet al., 2018,

    Experimental evidence of radiation reaction in the collision of a high-intensity laser pulse with a laser-wakefield accelerated electron beam

    , Physical Review X, Vol: 8, ISSN: 2160-3308

    The dynamics of energetic particles in strong electromagnetic fields can be heavily influenced by the energy loss arising from the emission of radiation during acceleration, known as radiation reaction. When interacting with a high-energy electron beam, today’s lasers are sufficiently intense to explore the transition between the classical and quantum radiation reaction regimes. We present evidence of radiation reaction in the collision of an ultrarelativistic electron beam generated by laser-wakefield acceleration (ϵ>500  MeV) with an intense laser pulse (a0>10). We measure an energy loss in the postcollision electron spectrum that is correlated with the detected signal of hard photons (γ rays), consistent with a quantum description of radiation reaction. The generated γ rays have the highest energies yet reported from an all-optical inverse Compton scattering scheme, with critical energy ϵcrit>30  MeV.

  • Journal article
    Warwick J, Dzelzainis T, Dieckmann ME, Schumaker W, Doria D, Romagnani L, Poder K, Cole JM, Alejo A, Yeung M, Krushelnick K, Mangles SPD, Najmudin Z, Reville B, Samarin GM, Symes DD, Thomas AGR, Borghesi M, Sarri Get al., 2017,

    Experimental observation of a current-driven instability in a neutral electron-positron beam

    , Physical Review Letters, Vol: 119, ISSN: 0031-9007

    We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (≥1  T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of εB≈10−3 is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.

  • Journal article
    Poder K, Cole JM, Wood JC, Lopes NC, Alatabi S, Foster PS, Kamperidis C, Kononenko O, Palmer CA, Rusby D, Sahai A, Sarri G, Symes DR, Warwick JR, Mangles SPD, Najmudin Zet al., 2017,

    Measurements of self-guiding of ultrashort laser pulses over long distances

    , Plasma Physics and Controlled Fusion, Vol: 60, ISSN: 0741-3335

    We report on the evaluation of the performance of self-guiding over extended distances with $f/20$ and $f/40$ focussing geometries. Guiding over $39\,\mathrm{mm}$ or more than 100 Rayleigh ranges was observed with the $f/20$ optic at ${n}_{e}=1.5\times {10}^{18}\,{\mathrm{cm}}^{-3}$. Analysis of guiding performance found that the extent of the exiting laser spatial mode closely followed the matched spot size predicted by 3D nonlinear theory. Self-guiding with an $f/40$ optic was also characterised, with guided modes observed for a plasma length of $90\,\mathrm{mm}$ and a plasma density of ${n}_{e}=9.5\times {10}^{17}\,{\mathrm{cm}}^{-3}$. This corresponds to self-guided propagation over 53 Rayleigh ranges and is similar to distances obtained with discharge plasma channel guiding.

  • Journal article
    Ridgers CP, Blackburn TG, Del Sorbo D, Bradley LE, Slade-Lowther C, Baird CD, Mangles SPD, McKenna P, Marklund M, Murphy CD, Thomas AGRet al., 2017,

    Signatures of quantum effects on radiation reaction in laser-electron-beam collisions

    , JOURNAL OF PLASMA PHYSICS, Vol: 83, ISSN: 0022-3778
  • Journal article
    Cowley J, Thornton C, Arran C, Shalloo RJ, Corner L, Cheung G, Gregory CD, Mangles SPD, Matlis NH, Symes DR, Walczak R, Hooker SMet al., 2017,

    Excitation and control of plasma wakefields by multiple laser pulses

    , Physical Review Letters, Vol: 119, ISSN: 1079-7114

    We demonstrate experimentally the resonant excitation of plasma waves by trains of laser pulses. We also take an important first step to achieving an energy recovery plasma accelerator by showing that a plasma wave can be damped by an out-of-resonance trailing laser pulse. The measured laser wakefields are found to be in excellent agreement with analytical and numerical models of wakefield excitation in the linear regime. Our results indicate a promising direction for achieving highly controlled, GeV-scale laser-plasma accelerators operating at multikilohertz repetition rates.

  • Conference paper
    Walker PA, Alesini PD, Alexandrova AS, Anania MP, Andreev NE, Andriyash I, Aschikhin A, Assmann RW, Audet T, Bacci A, Barna IF, Beaton A, Beck A, Beluze A, Bernhard A, Bielawski S, Bisesto FG, Boedewadt J, Brandi F, Bringer O, Brinkmann R, Bruendermann E, Buescher M, Bussmann M, Bussolino GC, Chance A, Chanteloup JC, Chen M, Chiadroni E, Cianchi A, Clarke J, Cole J, Couprie ME, Croia M, Cros B, Dale J, Dattoli G, Delerue N, Delferriere O, Delinikolas P, Dias J, Dorda U, Ertel K, Pousa AF, Ferrario M, Filippi F, Fils J, Fiorito R, Fonseca RA, Galimberti M, Gallo A, Garzella D, Gastinel P, Giove D, Giribono A, Gizzi LA, Gruener FJ, Habib AF, Haefner LC, Heinemann T, Hidding B, Holzer BJ, Hooker SM, Hosokai T, Irman A, Jaroszynski DA, Jaster-Merz S, Joshi C, Kaluza MC, Kando M, Karger OS, Karsch S, Khazanov E, Khikhlukha D, Knetsch A, Kocon D, Koester P, Kononenko O, Korn G, Kostyukov I, Labate L, Lechner C, Leemans WP, Lehrach A, Li FY, Li X, Libov V, Lifschitz A, Litvinenko V, Lu W, Maier AR, Malka V, Manahan GG, Mangles SPD, Marchetti B, Marocchino A, De la Ossa AM, Martins JL, Massimo F, Mathieu F, Maynard G, Mehrling TJ, Molodozhentsev AY, Mosnier A, Mostacci A, Mueller AS, Najmudin Z, Nghiem PAP, Nguyen F, Niknejadi P, Osterhoff J, Papadopoulos D, Patrizi B, Pattathil R, Petrillo V, Pocsai MA, Poder K, Pompili R, Pribyl L, Pugacheva D, Romeo S, Rossi AR, Roussel E, Sahai AA, Scherkl P, Schramm U, Schroeder CB, Schwindling J, Scifo J, Serafini L, Sheng ZM, Silva LO, Silva T, Simon C, Sinha U, Specka A, Streeter MJV, Svystun EN, Symes D, Szwaj C, Tauscher G, Thomas AGR, Thompson N, Toci G, Tomassini P, Vaccarezza C, Vannini M, Vieira JM, Villa F, Wahlstrom C-G, Walczak R, Weikum MK, Welsch CP, Wiemann C, Wolfenden J, Xia G, Yabashi M, Yu L, Zhu J, Zigler Aet al., 2017,

    Horizon 2020 EuPRAXIA design study

    , 8th International Particle Accelerator Conference (IPAC), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
  • Journal article
    Mangles SPD, Smid M, Gallardo Gonzalez I, Ekerfelt H, Bjorklund Svensson J, Hansson M, Wood JC, Persson A, Lundh O, Falk Ket al., 2017,

    Highly efficient angularly resolving x-ray spectrometer optimized for absorption measurements with collimated sources

    , Review of Scientific Instruments, Vol: 88, ISSN: 1089-7623

    Highly collimated betatron radiation from a laser wakefield accelerator is a promising tool for spectroscopic measurements. Therefore, there is a requirement to create spectrometers suited to the unique properties of such a source. We demonstrate a spectrometer which achieves an energy resolution of <5 eV at 9 keV (E∕ΔE>1800) and is angularly resolving the x-ray emission allowing the reference and spectrum to be recorded at the same time. The single photon analysis is used to significantly reduce the background noise. Theoretical performance of various configurations of the spectrometer is calculated by a ray-tracing algorithm. The properties and performance of the spectrometer including the angular and spectral resolution are demonstrated experimentally on absorption above the K-edge of a Cu foil backlit by a laser-produced betatron radiation x-ray beam.

  • Journal article
    Alejo A, Krygier AG, Ahmed H, Morrison JT, Clarke RJ, Fuchs J, Green A, Green JS, Jung D, Kleinschmidt A, Najmudin Z, Nakamura H, Norreys P, Notley M, Oliver M, Roth M, Vassura L, Zepf M, Borghesi M, Freeman RR, Kar Set al., 2017,

    High flux, beamed neutron sources employing deuteron-rich ion beams from D2O-ice layered targets

  • Journal article
    Robinson TS, Consoli F, Giltrap S, Eardley S, Hicks G, Ditter E, Ettlinger O, Stuart N, Notley M, De Angelis R, Najmudin Z, Smith Ret al., 2017,

    Low-noise time-resolved optical sensing of electromagnetic pulses from petawatt laser-matter interactions

    , Scientific Reports, Vol: 7, ISSN: 2045-2322

    We report on the development and deployment of an optical diagnostic for single-shot measurement of the electric-field components of electromagnetic pulses from high-intensity laser-matter interactions in a high-noise environment. The electro-optic Pockels effect in KDP crystals was used to measure transient electric fields using a geometry easily modifiable for magnetic field detection via Faraday rotation. Using dielectric sensors and an optical fibre-based readout ensures minimal field perturbations compared to conductive probes and greatly limits unwanted electrical pickup between probe and recording system. The device was tested at the Vulcan Petawatt facility with 1020 W cm−2 peak intensities, the first time such a diagnostic has been used in this regime. The probe crystals were located ~1.25 m from target and did not require direct view of the source plasma. The measured signals compare favourably with previously reported studies from Vulcan, in terms of the maximum measured intra-crystal field of 10.9 kV/m, signal duration and detected frequency content which was found to match the interaction chamber’s horizontal-plane fundamental harmonics of 76 and 101 MHz. Methods for improving the diagnostic for future use are also discussed in detail. Orthogonal optical probes offer a low-noise alternative for direct simultaneous measurement of each vector field component.

  • Conference paper
    Martin P, Doria D, Romagnani L, Ahmed H, McIlvenny A, Scullion C, Williamson SDR, Ditter EJ, Hicks G, Ettlinger OC, Scott GG, Symes DR, Booth N, Sgattoni A, Macchi A, Kar S, McKenna P, Najmudin Z, Neely D, Zepf M, Borghesi Met al., 2017,

    Transition to light sail acceleration using ultraintense femtosecond pulses

    Presented are results from experimental campaigns undertaken on the Gemini laser system at the Central Laser Facility in the UK. In these experiments amorphous carbon targets ranging in thickness from 10nm to 100nm were irradiated with high contrast 40fs pulses with an intensity up to 1021 W/cm2, for both circular and linear polarisations and the resulting proton and ion spectra compared. Examining the highest energies achieved for a given polarisation and target thickness, allows to identify the transition from TNSA to LS. Observations of the optimal target thickness for ion acceleration are compared to analytical predictions from LS theory, in addition to results from Particle in Cell modelling.

  • Journal article
    Sarri G, Warwick J, Schumaker W, Poder K, Cole J, Doria D, Dzelzainis T, Krushelnick K, Kuschel S, Mangles SPD, Najmudin Z, Romagnani L, Samarin GM, Symes D, Thomas AGR, Yeung M, Zepf Met al., 2016,

    Spectral and spatial characterisation of laser-driven positron beams

  • Conference paper
    Scullion C, Doria D, Romagnani L, Ahmed H, Alejo A, Ettlinger OC, Gray RJ, Green J, Hicks GS, Jung D, Naughton K, Padda H, Poder K, Scott GG, Symes DR, Kar S, McKenna P, Najmudin Z, Neely D, Zepf M, Borghesi Met al., 2016,

    Angularly resolved characterization of ion beams from laser-ultrathin foil interactions

    , 4th International Conference on Frontiers in Diagnostics Technologies, Publisher: IOP PUBLISHING LTD, ISSN: 1748-0221
  • Conference paper
    Ting A, Hafizi B, Helle M, Chen Y-H, Gordon D, Kaganovich D, Polyanskiy M, Pogorelsky I, Babzien M, Miao C, Dover N, Najmudin Z, Ettlinger Oet al., 2016,

    Staging and Laser Acceleration of Ions in Underdense Plasma

    , 17th Advanced Accelerator Concepts Workshop (AAC), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Conference paper
    Chen Y-H, Helle M, Ting A, Gordon D, Dover N, Ettlinger O, Najmudin Z, Polyanskiy M, Pogorelsky I, Babzien Met al., 2016,

    Laser Acceleration of Protons with an Optically Shaped, Near-Critical Hydrogen Gas Target

    , 17th Advanced Accelerator Concepts Workshop (AAC), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Journal article
    Smyth AG, Sarri G, Vranic M, Amano Y, Doria D, Guillaume E, Habara H, Heathcote R, Hicks G, Najmudin Z, Nakamura H, Norreys PA, Kar S, Silva LO, Tanaka KA, Vieira J, Borghesi Met al., 2016,

    Erratum: “Magnetic field generation during intense laser channelling in underdense plasma” [Phys. Plasmas 23, 063121 (2016)]

    , Physics of Plasmas, Vol: 23, ISSN: 1089-7674
  • Journal article
    Smyth AG, Sarri G, Vranic M, Amano Y, Doria D, Guillaume E, Habara H, Heathcote R, Hicks G, Najmudin Z, Nakamura H, Norreys PA, Kar S, Silva LO, Tanaka KA, Vieira J, Borghesi Met al., 2016,

    Magnetic field generation during intense laser channelling in underdense plasma

    , Physics of Plasmas, Vol: 23, ISSN: 1089-7674

    Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.

  • Conference paper
    Bracco C, Amorim LD, Assmann R, Batsch F, Bingham R, Burt G, Buttenschoen B, Butterworth A, Caldwell A, Chattopadhyay S, Cipiccia S, Deacon LC, Doebert S, Dorda U, Feldbaumer E, Fonseca RA, Fedossev V, Goddard B, Grebenyuk J, Grulke O, Gschwendtner E, Hansen J, Hessler C, Hofle W, Holloway J, Jaroszynski D, Jenkins M, Jensen L, Jolly S, Jones R, Kasim MF, Lopes N, Lotov K, Mandry SR, Martyanov M, Meddahi M, Mete O, Minakov V, Moody J, Muggli P, Najmudin Z, Norreys PA, Oez E, Pardons A, Petrenko A, Pukhov A, Rieger K, Reimann O, Seryi AA, Shaposhnikova E, Sherwood P, Silva LO, Sosedkin A, Tarkeshian R, Trines RMGM, Velotti FM, Vieira J, Vincke H, Welsch C, Wing M, Xia Get al., 2016,

    AWAKE: A Proton-Driven Plasma Wakefield Acceleration Experiment at CERN

    , 37th International Conference on High Energy Physics (ICHEP), Publisher: ELSEVIER SCIENCE BV, Pages: 175-180, ISSN: 2405-6014
  • Journal article
    Siminos E, Skupin S, Savert A, Cole JM, Mangles SPD, Kaluza MCet al., 2016,

    Modeling ultrafast shadowgraphy in laser-plasma interaction experiments

    , Plasma Physics and Controlled Fusion, Vol: 58, ISSN: 1361-6587

    Ultrafast shadowgraphy is a new experimental technique that uses few cycle laser pulses to imagedensity gradients in a rapidly evolving plasma. It enables structures that move at speeds close tothe speed of light, such as laser driven wakes, to be visualized. Here we study the process of shadowgraphicimage formation during the propagation of a few cycle probe pulse transversely througha laser-driven wake using three-dimensional particle-in-cell simulations. In order to construct syntheticshadowgrams a near-field snapshot of the ultrashort probe pulse is analyzed by means ofFourier optics, taking into account the effect of a typical imaging setup. By comparing syntheticand experimental shadowgrams we show that the generation of synthetic data is crucial for the correctinterpretation of experiments. Moreover, we study the dependence of synthetic shadowgramson various parameters such as the imaging system aperture, the position of the object plane andthe probe pulse delay, duration and wavelength. Finally, we show that time-dependent informationfrom the interaction can be recovered from a single shot by using a broadband, chirped probe pulseand subsequent spectral filtering.

  • Journal article
    Kononenko O, Lopes NC, Cole JM, Kamperidis C, Mangles SPD, Najmudin Z, Osterhoff J, Poder K, Rusby D, Symes DR, Warwick J, Wood JC, Palmer CAJet al., 2016,

    2D hydrodynamic simulations of a variable length gas target for density down-ramp injection of electrons into a laser wakefield accelerator

    , Nuclear Instruments & Methods in Physics Research Section A - Accelerators Spectrometers Detectors and Associated Equipment, Vol: 829, Pages: 125-129, ISSN: 0168-9002

    In this work, two-dimensional (2D) hydrodynamic simulations of a variable length gas cell were performed using the open source fluid code OpenFOAM. The gas cell was designed to study controlled injection of electrons into a laser-driven wakefield at the Astra Gemini laser facility. The target consists of two compartments: an accelerator and an injector section connected via an aperture. A sharp transition between the peak and plateau density regions in the injector and accelerator compartments, respectively, was observed in simulations with various inlet pressures. The fluid simulations indicate that the length of the down-ramp connecting the sections depends on the aperture diameter, as does the density drop outside the entrance and the exit cones. Further studies showed, that increasing the inlet pressure leads to turbulence and strong fluctuations in density along the axial profile during target filling, and consequently, is expected to negatively impact the accelerator stability.

  • Journal article
    Behm KT, Zhao TZ, Cole JM, Maksimchuk A, Mangles SPD, Nees J, Wood JC, Yanovsky V, Krushelnick K, Thomas AGRet al., 2016,

    Ionization injection effects in x-ray spectra generated by betatron oscillations in a laser wakefield accelerator

    , Plasma Physics and Controlled Fusion, Vol: 58, ISSN: 1361-6587
  • Conference paper
    Symes DR, Najmudin Z, Cole JM, Wood JC, Lopes NC, Poder K, Abel P, Abel RL, Alatabi S, Kneip S, Mecseki K, Winkler M, Foster PS, Norris DP, Teboul L, Johnson S, Szoke-Kovacs Z, Sandholzer M, Botchway S, Gratton S, Hill MA, De Lazzari M, Thomson Jet al., 2016,

    High-resolution tomographic imaging using coherent hard x-rays from compact laser driven accelerators

    , Compact EUV & X-ray Light Sources 2016, Publisher: OSA Publishing

    Extremely bright coherent femtosecond x-ray pulses are generated in compact laserdriven electron accelerators. Micro-tomography obtained with the Gemini laser indicates the usefulness of these sources in research and clinical applications.

  • Journal article
    Pogorelsky IV, Babzien M, Ben-Zvi I, Polyanskiy MN, Skaritka J, Tresca O, Dover NP, Najmudin Z, Lu W, Cook N, Ting A, Chen Y-Het al., 2016,

    Extending laser plasma accelerators into the mid-IR spectral domain with a next-generation ultra-fast CO2 laser

  • Conference paper
    Gschwendtner E, Adli E, Amorim L, Apsimon R, Assmann R, Bachmann A-M, Batsch F, Bauche J, Olsen VKB, Bernardini M, Bingham R, Biskup B, Bohl T, Bracco C, Burrows PN, Burt G, Buttenschoen B, Butterworth A, Caldwell A, Cascella M, Chevallay E, Cipiccia S, Damerau H, Deacon L, Dirksen R, Doebert S, Dorda U, Farmer J, Fedosseev V, Feldbaumer E, Fiorito R, Fonseca R, Friebel F, Gorn AA, Grulke O, Hansen J, Hessler C, Hofle W, Holloway J, Huether M, Jaroszynski D, Jensen L, Jolly S, Joulaei A, Kasim M, Keeble F, Li Y, Liu S, Lopes N, Lotov KV, Mandry S, Martorelli R, Martyanov M, Mazzoni S, Mete O, Minakov VA, Mitchell J, Moody J, Muggli P, Najmudin Z, Norreys R, Oez E, Pardons A, Pepitone K, Petrenko A, Plyushchev G, Pukhov A, Rieger K, Ruhl H, Salveter E, Savard N, Schmidt J, Seryi A, Shaposhnikova E, Sheng ZM, Sherwood R, Silva L, Soby L, Sosedkin AP, Spitsyn RI, Trines R, Tuev PV, Turner M, Verzilov V, Vieira J, Vincke H, Wei Y, Welsch CP, Wing M, Xia G, Zhang Het al., 2016,

    AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

    , 2nd Workshop on European Advanced Accelerator Concepts (EAAC), Publisher: ELSEVIER SCIENCE BV, Pages: 76-82, ISSN: 0168-9002
  • Conference paper
    King M, Gray RJ, Powell HW, MacLellan DA, Gonzalez-Izquierdo B, Stockhausen LC, Hicks GS, Dover NP, Rusby DR, Carroll DC, Padda H, Torres R, Kar S, Clarke RJ, Musgrave IO, Najmudin Z, Borghesi M, Neely D, McKenna Pet al., 2016,

    Ion acceleration and plasma jet formation in ultra-thin foils undergoing expansion and relativistic transparency

    , 2nd Workshop on European Advanced Accelerator Concepts (EAAC), Publisher: Elsevier, Pages: 163-166, ISSN: 0168-9002

    At sufficiently high laser intensities, the rapid heating to relativistic velocities and resulting decompression of plasma electrons in an ultra-thin target foil can result in the target becoming relativistically transparent to the laser light during the interaction. Ion acceleration in this regime is strongly affected by the transition from an opaque to a relativistically transparent plasma. By spatially resolving the laser-accelerated proton beam at near-normal laser incidence and at an incidence angle of 30°, we identify characteristic features both experimentally and in particle-in-cell simulations which are consistent with the onset of three distinct ion acceleration mechanisms: sheath acceleration; radiation pressure acceleration; and transparency-enhanced acceleration. The latter mechanism occurs late in the interaction and is mediated by the formation of a plasma jet extending into the expanding ion population. The effect of laser incident angle on the plasma jet is explored.

  • Journal article
    Dover N, Cook N, Tresca O, Ettlinger O, Maharjan C, Polyanskiy M, Shkolnikov P, Pogorelsky I, Najmudin Zet al., 2016,

    Optical shaping of gas targets for laser plasma ion sources

    , Journal of Plasma Physics, Vol: 82, ISSN: 1469-7807

    We report on the experimental demonstration of a technique to generate steep densitygradients in gas jet targets of interest to laser plasma ion acceleration. By using anintentional low energy prepulse, we generated a hydrodynamic blast wave in the gas toshape the target prior to the arrival of an intense CO2 (λ ≈ 10 µm) drive pulse. Thistechnique has been recently shown to facilitate the generation of ion beams by shockwaveacceleration (Tresca et al. 2015). Here, we discuss and introduce a model to understandthe generation of these blast waves and discuss in depth the experimental realisationof the technique, supported by hydrodynamics simulations. With appropriate prepulseenergy and timing, this blast wave can generate steepened density gradients as short asl ≈ 20 µm (1/e), opening up new possibilities for laser-plasma studies with near-criticalgaseous targets.

  • Journal article
    Dover N, Palmer CAJ, Streeter MJV, Ahmed H, Albertazzi B, Borghesi M, Carroll DC, Fuchs J, Heathcote R, Hilz P, Kakolee KF, Kar S, Kodama R, Kon A, MacLellan DA, McKenna P, Nagel SR, Neely D, Notley MM, Nakatsutsumi M, Prasad R, Scott G, Tampo M, Zepf M, Schreiber J, Najmudin Zet al., 2016,

    Buffered high charge spectrally-peaked proton beams in the relativistic-transparency regime

    , New Journal of Physics, Vol: 18, ISSN: 1367-2630

    Spectrally-peaked proton beams of high charge (Ep ≈ 8 MeV, ∆E ≈4 MeV, N ≈ 50 nC ) have been observed from the interaction of an intense laser(> 1019 Wcm−2) with ultrathin CH foils, as measured by spectrally-resolved full beamprofiles. These beams are reproducibly generated for foil thicknesses 5-100 nm, andexhibit narrowing divergence with decreasing target thickness down to ≈ 8◦for 5 nm.Simulations demonstrate that the narrow energy spread feature is a result of bufferedacceleration of protons. The radiation pressure at the front of the target results inasymmetric sheath fields which permeate throughout the target, causing preferentialforward acceleration. Due to their higher charge-to-mass ratio, the protons outrun acarbon plasma driven in the relativistic transparency regime.

  • Journal article
    Caldwell A, Adli E, Amorim L, Apsimon R, Argyropoulos T, Assmann R, Bachmann AM, Batsch F, Bauche J, Berglyd Olsen VK, Bernardini M, Bingham R, Biskup B, Bohl T, Bracco C, Burrows PN, Burt G, Buttenschön B, Butterworth A, Cascella M, Chattopadhyay S, Chevallay E, Cipiccia S, Damerau H, Deacon L, Dirksen P, Doebert S, Dorda U, Elsen E, Farmer J, Fartoukh S, Fedosseev V, Feldbaumer E, Fiorito R, Fonseca R, Friebel F, Geschonke G, Goddard B, Gorn AA, Grulke O, Gschwendtner E, Hansen J, Hessler C, Hillenbrand S, Hofle W, Holloway J, Huang C, Hüther M, Jaroszynski D, Jensen L, Jolly S, Joulaei A, Kasim M, Keeble F, Kersevan R, Kumar N, Li Y, Liu S, Lopes N, Lotov KV, Lu W, Machacek J, Mandry S, Martin I, Martorelli R, Martyanov M, Mazzoni S, Meddahi M, Merminga L, Mete O, Minakov VA, Mitchell J, Moody J, Müller AS, Najmudin Z, Noakes TCQ, Norreys P, Osterhoff J, Öz E, Pardons A, Pepitone K, Petrenko Aet al., 2016,

    Path to AWAKE: Evolution of the concept

    , Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 829, Pages: 3-16, ISSN: 0168-9002

    This paper describes the conceptual steps in reaching the design of the AWAKE experiment currently under construction at CERN. We start with an introduction to plasma wakefield acceleration and the motivation for using proton drivers. We then describe the self-modulation instability - a key to an early realization of the concept. This is then followed by the historical development of the experimental design, where the critical issues that arose and their solutions are described. We conclude with the design of the experiment as it is being realized at CERN and some words on the future outlook. A summary of the AWAKE design and construction status as presented in this conference is given in Gschwendtner et al. [1].

  • Conference paper
    Cook N, Tresca O, Dover NP, Maharjan C, Polyanskiy MN, Najmudin Z, Shkolnikov P, Pogorelsky Iet al., 2016,

    Hydrodynamic Shaping of Gas Jets for Laser Driven Shock Acceleration of Helium Ions

    , 16th Advanced Accelerator Concepts Workshop, Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Conference paper
    Najmudin Z, Fiuza F, Fernandez JC, 2016,

    Summary of Working Group 6: Ion Acceleration with Lasers

    , 16th Advanced Accelerator Concepts Workshop, Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Journal article
    Turcu ICE, Negoita F, Jaroszynski DA, Mckenna P, Balascuta S, Ursescu D, Dancus I, Cernaianu MO, Tataru MV, Ghenuche P, Stutman D, Boianu A, Risca M, Toma M, Petcu C, Acbas G, Yoffe SR, Noble A, Ersfeld B, Brunetti E, Capdessus R, Murphy C, Ridgers CP, Neely D, Mangles SPD, Gray RJ, Thomas AGR, Kirk JG, Ilderton A, Marklund M, Gordon DF, Hafizi B, Kaganovich D, Palastro JP, D'Humieres E, Zepf M, Sarri G, Gies H, Karbstein F, Schreiber J, Paulus GG, Dromey B, Harvey C, Di Piazza A, Keitel CH, Kaluza MC, Gales S, Zamfir NVet al., 2016,


    , ROMANIAN REPORTS IN PHYSICS, Vol: 68, Pages: S145-S231, ISSN: 1221-1451
  • Journal article
    Cole JM, Wood JC, Lopes NC, Poder K, Abel RL, Alatabi S, Bryant JSJ, Jin A, Kneip S, Mecseki K, Parker S, Symes DR, Sandholzer MA, Mangles SPD, Najmudin Zet al., 2016,

    Tomography of human trabecular bone with a laser-wakefield driven x-ray source

    , Plasma Physics and Controlled Fusion, Vol: 58, ISSN: 1361-6587

    A laser-wakefield driven x-ray source is used for the radiography of human bone. The betatron motion of accelerated electrons generates x-rays which are hard (critical energy ${{E}_{\text{crit}}}>30$ keV), have small source size (<3 μm) and high average brightness. The x-rays are generated from a helium gas cell which is near-instantly replenishable, and thus the average photon flux is limited by the repetition rate of the driving laser rather than the breakdown of the x-ray source. A tomograph of a human bone sample was recorded with a resolution down to 50 μm. The photon flux was sufficiently high that a radiograph could be taken with each laser shot, and the fact that x-ray beams were produced on 97% of shots minimised failed shots and facilitated full micro-computed tomography in a reasonable time scale of several hours, limited only by the laser repetition rate. The x-ray imaging beamline length (not including the laser) is shorter than that of a synchrotron source due to the high accelerating fields and small source size. Hence this interesting laboratory-based source may one day bridge the gap between small microfocus x-ray tubes and large synchrotron facilities.

  • Journal article
    Doria D, Kar S, Ahmed H, Alejo A, Fernandez J, Cerchez M, Gray RJ, Hanton F, MacLellan DA, McKenna P, Najmudin Z, Neely D, Romagnani L, Ruiz JA, Sarri G, Scullion C, Streeter M, Swantusch M, Willi O, Zepf M, Borghesi Met al., 2015,

    Calibration of BAS-TR image plate response to high energy (3-300 MeV) carbon ions

  • Journal article
    Deas RM, Wilson LA, Rusby D, Alejo A, Allott R, Black PP, Black SE, Borghesi M, Brenner CM, Bryant J, Clarke RJ, Collier JC, Edwards B, Foster P, Greenhalgh J, Hernandez-Gomez C, Kar S, Lockley D, Moss RM, Najmudin Z, Pattathil R, Symes D, Whittle MD, Wood JC, McKenna P, Neely Det al., 2015,

    A laser driven pulsed X-ray backscatter technique for enhanced penetrative imaging

    , Journal of X-Ray Science and Technology, Vol: 23, Pages: 791-797, ISSN: 1095-9114

    X-ray backscatter imaging can be used for a wide range of imaging applications, in particular for industrial inspection and portal security. Currently, the application of this imaging technique to the detection of landmines is limited due to the surrounding sand or soil strongly attenuating the 10s to 100s of keV X-rays required for backscatter imaging. Here, we introduce a new approach involving a 140 MeV short-pulse (< 100 fs) electron beam generated by laser wakefield acceleration to probe the sample, which produces Bremsstrahlung X-rays within the sample enabling greater depths to be imaged. A variety of detector and scintillator configurations are examined, with the best time response seen from an absorptive coated BaF2 scintillator with a bandpass filter to remove the slow scintillation emission components. An X-ray backscatter image of an array of different density and atomic number items is demonstrated. The use of a compact laser wakefield accelerator to generate the electron source, combined with the rapid development of more compact, efficient and higher repetition rate high power laser systems will make this system feasible for applications in the field.

  • Journal article
    Powell HW, King M, Gray RJ, MacLellan DA, Gonzalez-Izquierdo B, Stockhausen LC, Hicks G, Dover NP, Rusby DR, Carroll DC, Padda H, Torres R, Kar S, Clarke RJ, Musgrave IO, Najmudin Z, Borghesi M, Neely D, McKenna Pet al., 2015,

    Proton acceleration enhanced by a plasma jet in expanding foils undergoing relativistic transparency

    , New Journal of Physics, Vol: 17, ISSN: 1367-2630

    Ion acceleration driven by the interaction of an ultraintense (2 × 1020 W cm−2) laser pulse with an ultrathin ($\leqslant 40$ nm) foil target is experimentally and numerically investigated. Protons accelerated by sheath fields and via laser radiation pressure are angularly separated and identified based on their directionality and signature features (e.g. transverse instabilities) in the measured spatial-intensity distribution. A low divergence, high energy proton component is also detected when the heated target electrons expand and the target becomes relativistically transparent during the interaction. 2D and 3D particle-in-cell simulations indicate that under these conditions a plasma jet is formed at the target rear, supported by a self-generated azimuthal magnetic field, which extends into the expanded layer of sheath-accelerated protons. Electrons trapped within this jet are directly accelerated to super-thermal energies by the portion of the laser pulse transmitted through the target. The resulting streaming of the electrons into the ion layers enhances the energy of protons in the vicinity of the jet. Through the addition of a controlled prepulse, the maximum energy of these protons is demonstrated experimentally and numerically to be sensitive to the picosecond rising edge profile of the laser pulse.

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