Imperial College London

ProfessorZulfikarNajmudin

Faculty of Natural SciencesDepartment of Physics

Professor of Physics
 
 
 
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Contact

 

z.najmudin Website

 
 
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Location

 

736Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

284 results found

Gruse JN, Streeter MJV, Thornton C, Armstrong CD, Baird CD, Bourgeois N, Cipiccia S, Finlay OJ, Gregory CD, Katzir Y, Lopes NC, Mangles SPD, Najmudin Z, Neely D, Pickard LR, Potter KD, Rajeev PP, Rusby DR, Underwood CID, Warnett JM, Williams MA, Wood JC, Murphy CD, Brenner CM, Symes DRet al., 2020, Application of compact laser-driven accelerator X-ray sources for industrial imaging, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 983, ISSN: 0168-9002

© 2020 X-rays generated by betatron oscillations of electrons in a laser-driven plasma accelerator were characterised and applied to imaging industrial samples. With a 125TW laser, a low divergence beam with 5.2±1.7 × 107photonsmrad−2 per pulse was produced with a synchrotron spectrum with a critical energy of 14.6±1.3keV. Radiographs were obtained of a metrology test sample, battery electrodes, and a damage site in a composite material. These results demonstrate the suitability of the source for non-destructive evaluation applications. The potential for industrial implementation of plasma accelerators is discussed.

Journal article

Dover NP, Nishiuchi M, Sakaki H, Kondo K, Lowe HF, Alkhimova MA, Ditter EJ, Ettlinger OC, Faenov AY, Hata M, Hicks GS, Iwata N, Kiriyama H, Koga JK, Miyahara T, Najmudin Z, Pikuz TA, Pirozhkov AS, Sagisaka A, Schramm U, Sentoku Y, Watanabe Y, Ziegler T, Zeil K, Kando M, Kondo Ket al., 2020, Demonstration of repetitive energetic proton generation by ultra-intense laser interaction with a tape target, High Energy Density Physics, Vol: 37, ISSN: 1574-1818

© 2020 Elsevier B.V. High power laser systems are an attractive driver for compact energetic ion sources. We demonstrate repetitive acceleration at 0.1 Hz of proton beams up to 40 MeV from a reeled tape target irradiated by ultra-high intensities up to 5 × 1021 Wcm−2 and laser energies ≈ 15 J using the J-KAREN-P laser system. We investigate the stability of the source and its behaviour with laser spot focal size. We compare the scaling of proton energy with laser energy to a recently developed analytical model, and also demonstrate that it is possible to reach energies up to 50 MeV on a single shot with a lower laser energy ≈ 10 J by using a thinner target, motivating development of high repetition targetry suitable for thinner targets.

Journal article

Kondo K, Nishiuchi M, Sakaki H, Dover NP, Lowe HF, Miyahara T, Watanabe Y, Ziegler T, Zeil K, Schramm U, Ditter EJ, Hicks GS, Ettlinger OC, Najmudin Z, Kiriyama H, Kando M, Kondo Ket al., 2020, High-intensity laser-driven oxygen source from cw laser-heated titanium tape targets, Crystals, Vol: 10, Pages: 1-10

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The interaction of high-intensity laser pulses with solid targets can be used as a highly charged, energetic heavy ion source. Normally, intrinsic contaminants on the target surface suppress the performance of heavy ion acceleration from a high-intensity laser–target interaction, resulting in preferential proton acceleration. Here, we demonstrate that CW laser heating of 5 µm titanium tape targets can remove contaminant hydrocarbons in order to expose a thin oxide layer on the metal surface, ideal for the generation of energetic oxygen beams. This is demonstrated by irradiating the heated targets with a PW class high-power laser at an intensity of 5 × 1021 W/cm2, showing enhanced acceleration of oxygen ions with a non-thermal-like distribution. Our new scheme using a CW laser-heated Ti tape target is promising for use as a moderate repetition energetic oxygen ion source for future applications.

Journal article

Streeter MJV, Najmudin Z, 2020, Compton recoil effects in staging of laser wakefield accelerators, Physical Review Accelerators and Beams, Vol: 23

Journal article

Bloom MS, Streeter MJV, Kneip S, Bendoyro RA, Cheklov O, Cole JM, Doepp A, Hooker CJ, Holloway J, Jiang J, Lopes NC, Nakamura H, Norreys PA, Rajeev PP, Symes DR, Schreiber J, Wood JC, Wing M, Najmudin Z, Mangles SPDet al., 2020, Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator

We show that the properties of the electron beam and bright X-rays producedby a laser wakefield accelerator can be predicted if the distance over whichthe laser self-focuses and compresses prior to self-injection is taken intoaccount. A model based on oscillations of the beam inside a plasma bubble showsthat performance is optimised when the plasma length is matched to the laserdepletion length. With a 200~TW laser pulse this results in an X-ray beam withmedian photon energy of 20 keV, $> 10^{9}$ photons per shot and a peakbrightness of $4 \times 10^{23}$ photons s$^{-1}$ mrad$^{-2}$ mm$^{-2}$ (0.1 %BW)$^{-1}$.

Working paper

Mangles S, 2020, Bright x-ray radiation from plasma bubbles in an evolving laser wakefield accelerator, Physical Review Accelerators and Beams, Vol: 23, Pages: 061301 – 1-061301 – 6, ISSN: 2469-9888

We show that the properties of the electron beam and bright x rays produced by a laser wakefield accelerator can be predicted if the distance over which the laser self-focuses and compresses prior to self-injection is taken into account. A model based on oscillations of the beam inside a plasma bubble shows that performance is optimized when the plasma length is matched to the laser depletion length. With a 200 TW laser pulse, this results in an x-ray beam with a median photon energy of 20 keV, >6×108  photons above 1 keV per shot, and a peak brightness of 3×1022  photons s−1 mrad−2 mm−2 (0.1%  BW)−1.

Journal article

Hussein AE, Senabulya N, Ma Y, Streeter MJV, Kettle B, Dann SJD, Albert F, Bourgeois N, Cipiccia S, Cole JM, Finlay O, Gerstmayr E, González IG, Higginbotham A, Jaroszynski DA, Falk K, Krushelnick K, Lemos N, Lopes NC, Lumsdon C, Lundh O, Mangles SPD, Najmudin Z, Rajeev PP, Schlepütz CM, Shahzad M, Smid M, Spesyvtsev R, Symes DR, Vieux G, Willingale L, Wood JC, Shahani AJ, Thomas AGRet al., 2020, Author Correction: Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures, Scientific Reports, Vol: 10, ISSN: 2045-2322

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Journal article

Passalidis S, Ettlinger OC, Hicks GS, Dover NP, Najmudin Z, Benis EP, Kaselouris E, Papadogiannis NA, Tatarakis M, Dimitriou Vet al., 2020, Hydrodynamic computational modelling and simulations of collisional shock waves in gas jet targets, HIGH POWER LASER SCIENCE AND ENGINEERING, Vol: 8, ISSN: 2095-4719

Journal article

Weikum MK, Akhter T, 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, Brandi F, Bringer O, Brinkmann R, Bründermann E, Büscher 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, Crump P, Dattoli G, Delerue N, Delferriere O, Delinikolas P, De Nicola S, Dias J, Dorda U, Fedele R, Pousa AF, Ferrario M, Filippi F, Fils J, Fiore G, Fonseca RA, Galimberti M, Gallo A, Garzella D, Gastinel P, Giove D, Giribono A, Gizzi LA, Grüner FJ, Habib AF, Heinemann T, Hidding B, Holzer BJ, Hooker SM, Hosokai T, Hübner M, Irman A, Jafarinia F, 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, Kruchinin K, Labate L, Lechner C, Leemans WP, Lehrach A, Li FY, Li X, Libov V, Lifschitz A, Litvinenko V, Lu W, Lundh O, Maier AR, Malka V, Manahan GG, Mangles SPD, Marchetti B, Marocchino Aet al., 2019, EuPRAXIA - A compact, cost-efficient particle and radiation source, ISSN: 0094-243X

© 2019 Author(s). Plasma accelerators present one of the most suitable candidates for the development of more compact particle acceleration technologies, yet they still lag behind radiofrequency (RF)-based devices when it comes to beam quality, control, stability and power efficiency. The Horizon 2020-funded project EuPRAXIA ("European Plasma Research Accelerator with eXcellence In Applications") aims to overcome the first three of these hurdles by developing a conceptual design for a first international user facility based on plasma acceleration. In this paper we report on the main features, simulation studies and potential applications of this future research infrastructure.

Conference paper

Kurup A, Pasternak J, Taylor R, Murgatroyd L, Ettlinger O, Shields W, Nevay L, Gruber S, Pozimski J, Lau HT, Long K, Blackmore V, Barber G, Najmudin Z, Yarnold Jet al., 2019, Simulation of a radiobiology facility for the Centre for the Clinical Application of Particles, Physica Medica, Vol: 65, Pages: 21-28, ISSN: 1120-1797

The Centre for the Clinical Application of Particles’ Laser-hybrid Accelerator for Radiobiological Applications (LhARA) facility is being studied and requires simulation of novel accelerator components (such as the Gabor lens capture system), detector simulation and simulation of the ion beam interaction with cells. The first stage of LhARA will provide protons up to 15 MeV for in vitro studies. The second stage of LhARA will use a fixed-field accelerator to increase the energy of the particles to allow in vivo studies with protons and in vitro studies with heavier ions.BDSIM, a Geant4 based accelerator simulation tool, has been used to perform particle tracking simulations to verify the beam optics design done by BeamOptics and these show good agreement. Design parameters were defined based on an EPOCH simulation of the laser source and a series of mono-energetic input beams were generated from this by BDSIM. The tracking results show the large angular spread of the input beam (0.2 rad) can be transported with a transmission of almost 100% whilst keeping divergence at the end station very low (<0.1 mrad). The legacy of LhARA will be the demonstration of technologies that could drive a step-change in the provision of proton and light ion therapy (i.e. a laser source coupled to a Gabor lens capture and a fixed-field accelerator), and a system capable of delivering a comprehensive set of experimental data that can be used to enhance the clinical application of proton and light ion therapy.

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.

Journal article

Dann SJD, Baird CD, Bourgeois N, Chekhlov O, Eardley S, Gregory CD, Gruse J-N, Hah J, Hazra D, Hawkes SJ, Hooker CJ, Krushelnick K, Manles SPD, Marshall VA, Murphy CD, Najmudin Z, Nees JA, Osterhoff J, Parry B, Pourmoussavi P, Rahul S, Rajeev PP, Rozario S, Scott JDE, Smith RA, Springate E, Tang Y, Tata S, Thomas AGR, Thornton C, Symes DR, Streeter MJet al., 2019, Laser wakefield acceleration with active feedback at 5 Hz, Physical Review Accelerators and Beams, Vol: 22, ISSN: 2469-9888

We describe the use of a genetic algorithm to apply active feedback to a laser wakefield accelerator at a higher power (10 TW) and a lower repetition rate (5 Hz) than previous work. The temporal shape of the drive laser pulse was adjusted automatically to optimize the properties of the electron beam. By changing the software configuration, different properties could be improved. This included the total accelerated charge per bunch, which was doubled, and the average electron energy, which was increased from 22 to 27 MeV. Using experimental measurements directly to provide feedback allows the system to work even when the underlying acceleration mechanisms are not fully understood, and, in fact, studying the optimized pulse shape might reveal new insights into the physical processes responsible. Our work suggests that this technique, which has already been applied with low-power lasers, can be extended to work with petawatt-class laser systems.

Journal article

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

Conference paper

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, HIGH POWER LASER SCIENCE AND ENGINEERING, Vol: 7, ISSN: 2095-4719

Journal article

Hussein AE, Senabulya N, Ma Y, Streeter MJV, Kettle B, Dann SJD, Albert F, Bourgeois N, Cipiccia S, Cole JM, Finlay O, Gerstmayr E, Gonzalez IG, Higginbotham A, Jaroszynski DA, Falk K, Krushelnick K, Lemos N, Lopes NC, Lumsdon C, Lundh O, Mangles SPD, Najmudin Z, Rajeev PP, Schleputz CM, Shahzad M, Smid M, Spesyvtsev R, Symes DR, Vieux G, Willingale L, Wood JC, Shahani AJ, Thomas AGRet al., 2019, Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures, Scientific Reports, Vol: 9, Pages: 1-13, ISSN: 2045-2322

Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials can provide insight into their processing, structure, and performance. To demonstrate the imaging capability of X-rays from an LWFA we have examined an irregular eutectic in the aluminum-silicon (Al-Si) system. The lamellar spacing of the Al-Si eutectic microstructure is on the order of a few micrometers, thus requiring high spatial resolution. We present comparisons between the sharpness and spatial resolution in phase contrast images of this eutectic alloy obtained via X-ray phase contrast imaging at the Swiss Light Source (SLS) synchrotron and X-ray projection microscopy via an LWFA source. An upper bound on the resolving power of 2.7 ± 0.3 μm of the LWFA source in this experiment was measured. These results indicate that betatron X-rays from laser wakefield acceleration can provide an alternative to conventional synchrotron sources for high resolution imaging of eutectics and, more broadly, complex microstructures.

Journal article

Nghiem PAP, Alesini D, Aschikhin A, Assmann RW, Audet T, Beck A, Chance A, Chen M, Chiadroni E, Cianchi A, Clarke JA, Couprie ME, Croia M, Cros B, Dattoli G, Del Dotto A, Delerue N, Dorda U, Pousa AF, Ferrario M, Fonseca RA, Ghaith A, Giribono A, Gizzi LA, Helm A, Hidding B, Hooker SM, Ibison MG, Jaroszynski DA, Kruchinin KO, Labate L, Lee P, Li X, Li FY, Libov V, Marchetti B, de la Ossa AM, Marx D, Massimo F, Mathieu F, Maynard G, Mazzotta Z, Mehrling TJ, Molodozhentsev AY, Mosnier A, Mostacci A, Najmudin Z, Nguyen F, Niknejadi P, Espinos DO, Pattathil R, Pompili R, Romeo S, Rossi AR, Schaper L, Sheng ZM, Shpakov V, Silva LO, Silva T, Simon C, Specka A, Stella A, Streeter MJV, Svystun EN, Symes D, Terzani D, Toci G, Tomassini P, Vaccarezza C, Vieira JM, Vujanovic M, Walczak R, Walker PA, Weikum MK, Welsch CP, Weng SM, Wiggins SM, Wolfenden J, Yoffe S, Zhu Jet al., 2019, EuPRAXIA, A STEP TOWARD A PLASMA-WAKEFIELD BASED ACCELERATOR WITH HIGH BEAM QUALITY, 10th International Particle Accelerator Conference (IPAC), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588

Conference paper

Najmudin Z, 2019, Laser Wakefield Accelerators: Plasma Wave Growth and Acceleration, Pages: 51-70, ISSN: 0930-8989

© 2019, Springer Nature Switzerland AG. Laser wakefield accelerators are now becoming established as indispensable laboratory tools. This is because of their ability to produce high energy electron beams in compact configurations. Here we outline the basic theory of laser wakefield acceleration. One dimensional plasma waves are considered and the differential equation for wakefield generation is derived. The case of wakefield generation at low laser intensity ((formula presented)) is considered to demonstrate the relation between the laser driver and the generated plasma wave. Finally acceleration in the plasma wave is considered. The importance of non-linear and three dimensional effects on the plasma wave growth are discussed.

Conference paper

Weikum MK, Akhter T, Alesini D, Alexandrova AS, Anania MP, Andreev NE, Andriyash IA, Aschikhin A, Assmann RW, Audet T, Bacci A, Barna IF, Beaton A, Beck A, Beluze A, Bernhard A, Bielawski S, Bisesto FG, Brandi F, Brinkmann R, Bruendermann E, Buescher M, Bussmann MH, Bussolino G, Chance A, Chen M, Chiadroni E, Cianchi A, Clarke JA, Cole J, Couprie ME, Croia M, Cros B, Crump PA, Dattoli G, Del Dotto A, Delerue N, De Nicola S, Dias JM, Dorda U, Fedele R, Pousa AF, Ferrario M, Filippi F, Fiore G, Fonseca RA, Galimberti M, Gallo A, Ghaith A, Giove D, Giribono A, Gizzi LA, Gruener FJ, Habib AF, Haefner C, Heinemann T, Hidding B, Holzer BJ, Hooker SM, Hosokai T, Huebner M, Irman A, Jafarinia FJ, Jaroszynski DA, Joshi C, Kaluza M, Kando M, Karger OS, Karsch S, Khazanov E, Khikhlukha D, Knetsch A, Kocon D, Koester P, Kononenko OS, Korn G, Kostyukov I, Kruchinin KO, Labate L, Le Blanc C, Lechner C, Leemans W, Lehrach A, Li X, Libov V, Lifschitz A, Litvinenko V, Lu W, Lundh O, Maier AR, Malka V, Manahan GG, Mangles SPD, Marchetti B, de la Ossa AM, Martins JL, Mason PD, Massimo F, Mathieu F, Maynard G, Mazzotta Z, Molodozhentsev AY, Mostacci A, Mueller A-S, Murphy CD, Najmudin Z, Nghiem PAP, Nguyen F, Niknejadi P, Osterhoff J, Espinos DO, Papadopoulos DN, Patrizi B, Petrillo V, Pocsai MA, Poder K, Pompili R, Pribyl L, Pugacheva D, Rajeev PP, Romeo S, Conti MR, Rossi AR, Rossmanith R, Roussel E, Sahai AA, Sarri G, Schaper L, Scherkl P, Schramm U, Schroeder CB, Scifo J, Serafini L, Sheng ZM, Siders C, Silva LO, Silva T, Simon C, Sinha U, Specka A, Streeter MJV, Svystun EN, Symes D, Szwaj C, Tauscher GE, Terzani D, Thompson N, Toci G, Tomassini P, Torres R, Ullmann D, Vaccarezza C, Vannini M, Vieira JM, Villa F, Wahlstrom C-G, Walczak R, Walker PA, Wang K, Welsch CP, Wiggins SM, Wolfenden J, Xia G, Yabashi M, Zhu J, Zigler Aet al., 2019, Status of the Horizon 2020 EuPRAXIA conceptual design study, 10th International Particle Accelerator Conference (IPAC), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588

Conference paper

Spesyvtsev R, Brunetti E, Vieux G, Shahzad M, Maitrallain A, Yoffe S, Ersfeld B, Kornaszewski A, Streeter MJ, Finlay O, Ma Y, Kettle B, Dann SJD, Albert F, Bourgeois N, Cipiccia S, Cole JM, Gerstmayr E, Gonzalez IG, Higginbotham A, Hussein AE, Falk K, Krushelnick K, Lemos N, Lopes NC, Lumsdon C, Lundh O, Mangles SPD, Najmudin Z, Rajeev PP, Smid M, Symes DR, Thomas AGR, Jaroszynski DAet al., 2019, Generation of electron high energy beams with a ring-like structure by a dual stage laser wakefield accelerator, Conference on Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X

Conference paper

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

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, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 909, Pages: 145-148, ISSN: 0168-9002

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, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 89, ISSN: 0034-6748

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

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

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

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, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 115, Pages: 6335-6340, ISSN: 0027-8424

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

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

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