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    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

    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

    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

    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

    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
    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.

    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
    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
    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

    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.,

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

    , Physical Review Letters, 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.

    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
    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.,

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

    , Applied Physics Letters, 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.

    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
    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 beheavily influenced by the energy loss arising from the emission of radiationduring acceleration, known as radiation reaction. When interacting with ahigh-energy electron beam, today's lasers are sufficiently intense to explorethe transition between the classical and quantum radiation reaction regimes. Wereport on the observation of radiation reaction in the collision of anultra-relativistic electron beam generated by laser wakefield acceleration($\varepsilon > 500$ MeV) with an intense laser pulse ($a_0 > 10$). We measurean energy loss in the post-collision electron spectrum that is correlated withthe detected signal of hard photons ($\gamma$-rays), consistent with a quantum(stochastic) description of radiation reaction. The generated $\gamma$-rayshave the highest energies yet reported from an all-optical inverse Comptonscattering scheme, with critical energy $\varepsilon_{\rm crit} > $ 30 MeV.

    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

    © OSA 2018. 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.

    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.

    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.

    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
    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.

    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
    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.

    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

    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.

    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

    © 2017 IOP Publishing Ltd. 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.

    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

    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
    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
    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
    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
    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.

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