Publications


Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics

PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 084013

R Assmann, R Bingham, T Bohl, C Bracco, B Buttenschoen, A Butterworth, A Caldwell, S Chattopadhyay, S Cipiccia, E Feldbaumer, RA Fonseca, B Goddard, M Gross, O Grulke, E Gschwendtner, J Holloway, C Huang, D Jaroszynski, S Jolly, P Kempkes, N Lopes, K Lotov, J Machacek, SR Mandry, JW McKenzie, M Meddahi, BL Militsyn, N Moschuering, P Muggli, Z Najmudin, TCQ Noakes, PA Norreys, E Oez, A Pardons, A Petrenko, A Pukhov, K Rieger, O Reimann, H Ruhl, E Shaposhnikova, LO Silva, A Sosedkin, R Tarkeshian, RMGN Trines, T Tueckmantel, J Vieira, H Vincke, M Wing, G Xia


Modelling gamma-ray photon emission and pair production in high-intensity laser-matter interactions

Journal of Computational Physics 260 (2014) 273-285

CP Ridgers, JG Kirk, R Duclous, TG Blackburn, CS Brady, K Bennett, TD Arber, AR Bell

In high-intensity (>1021 Wcm -2) laser-matter interactions gamma-ray photon emission by the electrons can strongly affect the electron's dynamics and copious numbers of electron-positron pairs can be produced by the emitted photons. We show how these processes can be included in simulations by coupling a Monte Carlo algorithm describing the emission to a particle-in-cell code. The Monte Carlo algorithm includes quantum corrections to the photon emission, which we show must be included if the pair production rate is to be correctly determined. The accuracy, convergence and energy conservation properties of the Monte Carlo algorithm are analysed in simple test problems. © 2013 Elsevier Inc.


The ATLAS(3D) project - XXV. Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 444 (2014) 3357-3387

T Naab, L Oser, E Emsellem, M Cappellari, D Krajnovic, RM McDermid, K Alatalo, E Bayet, L Blitz, M Bois, F Bournaud, M Bureau, A Crocker, RL Davies, TA Davis, PT de Zeeuw, P-A Duc, M Hirschmann, PH Johansson, S Khochfar, H Kuntschner, R Morganti, T Oosterloo, M Sarzi, N Scott, P Serra, G van de Ven, A Weijmans, LM Young


Observations of strong ion-ion correlations in dense plasmas

PHYSICS OF PLASMAS 21 (2014) ARTN 056302

T Ma, L Fletcher, A Pak, DA Chapman, RW Falcone, C Fortmann, E Galtier, DO Gericke, G Gregori, J Hastings, OL Landen, S Le Pape, HJ Lee, B Nagler, P Neumayer, D Turnbull, J Vorberger, TG White, K Wuensch, U Zastrau, SH Glenzer, T Doeppner


Performance of the K-band multi-object spectrograph (KMOS) on the ESO VLT

GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V 9147 (2014)

R Sharples, R Bender, AA Berbel, R Bennett, N Bezawada, R Castillo, M Cirasuolo, P Clark, G Davidson, R Davies, R Davies, M Dubbeldam, A Fairley, G Finger, NF Schreiber, R Genzel, R Haefner, A Hess, I Jung, I Lewis, D Montgomery, J Murray, B Muschielok, J Pirard, S Ramsey, P Rees, J Richter, D Robertson, I Robson, S Rolt, R Saglia, I Saviane, J Schlichter, L Schmidtobreik, A Segovia, A Smette, M Tecza, S Todd, M Wegner, E Wiezorrek


Evidence for a glassy state in strongly driven carbon.

Scientific reports 4 (2014) 5214-

CR Brown, DO Gericke, M Cammarata, BI Cho, T Döppner, K Engelhorn, E Förster, C Fortmann, D Fritz, E Galtier, SH Glenzer, M Harmand, P Heimann, NL Kugland, DQ Lamb, HJ Lee, RW Lee, H Lemke, M Makita, A Moinard, CD Murphy, B Nagler, P Neumayer, KU Plagemann, R Redmer, D Riley, FB Rosmej, P Sperling, S Toleikis, SM Vinko, J Vorberger, S White, TG White, K Wünsch, U Zastrau, D Zhu, T Tschentscher, G Gregori

Here, we report results of an experiment creating a transient, highly correlated carbon state using a combination of optical and x-ray lasers. Scattered x-rays reveal a highly ordered state with an electrostatic energy significantly exceeding the thermal energy of the ions. Strong Coulomb forces are predicted to induce nucleation into a crystalline ion structure within a few picoseconds. However, we observe no evidence of such phase transition after several tens of picoseconds but strong indications for an over-correlated fluid state. The experiment suggests a much slower nucleation and points to an intermediate glassy state where the ions are frozen close to their original positions in the fluid.


Local dependence of ion temperature gradient on magnetic configuration, rotational shear and turbulent heat flux in MAST

ArXiv (0)

Y-C Ghim, AR Field, AA Schekochihin, EG Highcock, C Michael, TMAST Team

Experimental data from the Mega Amp Spherical Tokamak (MAST) is used to show that the inverse gradient scale length of the ion temperature R/LTi (normalized to the major radius R) has its strongest local correlation with the rotational shear and the pitch angle of the magnetic field (or, equivalently, an inverse correlation with q/{\epsilon}, the safety factor/the inverse aspect ratio). Furthermore, R/LTi is found to be inversely correlated with the gyro-Bohm-normalized local turbulent heat flux estimated from the density fluctuation level measured using a 2D Beam Emission Spectroscopy (BES) diagnostic. These results can be explained in terms of the conjecture that the turbulent system adjusts to keep R/LTi close to a certain critical value (marginal for the excitation of turbulence) determined by local equilibrium parameters (although not necessarily by linear stability).


Do high-redshift quasars have powerful jets?

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 442 (2014) L81-L84

AC Fabian, SA Walker, A Celotti, G Ghisellini, P Mocz, KM Blundell, RG McMahon


A photon-photon collider in a vacuum hohlraum

Nature Photonics 8 (2014) 434-436

OJ Pike, F MacKenroth, EG Hill, SJ Rose

The ability to create matter from light is amongst the most striking predictions of quantum electrodynamics. Experimental signatures of this have been reported in the scattering of ultra-relativistic electron beams with laser beams, intense laser-plasma interactions and laser-driven solid target scattering. However, all such routes involve massive particles. The simplest mechanism by which pure light can be transformed into matter, Breit-Wheeler pair production (' 3' 3' €2 ' †' e + e ∼'), has never been observed in the laboratory. Here, we present the design of a new class of photon-photon collider in which a gamma-ray beam is fired into the high-temperature radiation field of a laser-heated hohlraum. Matching experimental parameters to current-generation facilities, Monte Carlo simulations suggest that this scheme is capable of producing of the order of 10 5 Breit-Wheeler pairs in a single shot. This would provide the first realization of a pure photon-photon collider, representing the advent of a new type of high-energy physics experiment. © 2014 Macmillan Publishers Limited.


The ATLAS(3D) project - XXVI. H I discs in real and simulated fast and slow rotators

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 444 (2014) 3388-3407

P Serra, L Oser, D Krajnovic, T Naab, T Oosterloo, R Morganti, M Cappellari, E Emsellem, LM Young, L Blitz, TA Davis, P-A Duc, M Hirschmann, A-M Weijmans, K Alatalo, E Bayet, M Bois, F Bournaud, M Bureau, AF Crocker, RL Davies, PT de Zeeuw, S Khochfar, H Kuntschner, P-Y Lablanche, RM McDermid, M Sarzi, N Scott


Compact laser accelerators for X-ray phase-contrast imaging

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372 (2014)

Z Najmudin, S Kneip, MS Bloom, SPD Mangles, O Chekhlov, AE Dangor, A Dopp, K Ertel, SJ Hawkes, J Holloway, CJ Hooker, J Jiang, NC Lopes, H Nakamura, PA Norreys, PP Rajeev, C Russo, MJV Streeter, DR Symes, M Wing

Advances in X-ray imaging techniques have been driven by advances in novel X-ray sources. The latest fourth-generation X-ray sources can boast large photon fluxes at unprecedented brightness. However, the large size of these facilities means that these sources are not available for everyday applications. With advances in laser plasma acceleration, electron beams can now be generated at energies comparable to those used in light sources, but in university-sized laboratories. By making use of the strong transverse focusing of plasma accelerators, bright sources of betatron radiation have been produced. Here, we demonstrate phase-contrast imaging of a biological sample for the first time by radiation generated by GeV electron beams produced by a laser accelerator. The work was performed using a greater than 300TW laser, which allowed the energy of the synchrotron source to be extended to the 10100 keV range. © 2014 The Author(s) Published by the Royal Society. All rights reserved.


Quantum radiation reaction in laser-electron-beam collisions.

Phys Rev Lett 112 (2014) 015001-

TG Blackburn, CP Ridgers, JG Kirk, AR Bell

It is possible using current high-intensity laser facilities to reach the quantum radiation reaction regime for energetic electrons. An experiment using a wakefield accelerator to drive GeV electrons into a counterpropagating laser pulse would demonstrate the increase in the yield of high-energy photons caused by the stochastic nature of quantum synchrotron emission: we show that a beam of 10(9) 1 GeV electrons colliding with a 30 fs laser pulse of intensity 10(22)  W cm(-2) will emit 6300 photons with energy greater than 700 MeV, 60× the number predicted by classical theory.


Optimizing stellarators for large flows

PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 094003

I Calvo, FI Parra, J Arturo Alonso, J Luis Velasco


Firehose and Mirror Instabilities in a Collisionless Shearing Plasma

PHYSICAL REVIEW LETTERS 112 (2014) ARTN 205003

MW Kunz, AA Schekochihin, JM Stone


Focus on high energy density physics

New Journal of Physics 16 (2014)

R Paul Drake, P Norreys

High-energy-density physics concerns the behavior of systems at high pressure, often involving the interplay of plasma, relativistic, quantum mechanical and electromagnetic effects. The field is growing rapidly in its scope of activity thanks to advances in experimental, laser and computational technologies. This 'focus on' collection presents papers discussing forefront research that spans the field, providing a sense of its breadth and of the interlinking of its parts. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Why stellar feedback promotes disc formation in simulated galaxies

Monthly Notices of the Royal Astronomical Society 443 (2014) 2092-2111

H Übler, T Naab, L Oser, M Aumer, LV Sales, SDM White

We study how feedback influences baryon infall on to galaxies using cosmological, zoom-in simulations of haloes with present mass Mvir = 6.9 × 1011 to 1.7 × 1012M⊙. Starting at z = 4 from identical initial conditions, implementations of weak and strong stellar feedback produce bulge- and disc-dominated galaxies, respectively. Strong feedback favours disc formation: (1) because conversion of gas into stars is suppressed at early times, as required by abundance matching arguments, resulting in flat star formation histories and higher gas fractions; (2) because 50 per cent of the stars form in situ from recycled disc gas with angular momentum only weakly related to that of the z = 0 dark halo; (3) because late-time gas accretion is typically an order of magnitude stronger and has higher specific angular momentum, with recycled gas dominating over primordial infall; (4) because 25-30 per cent of the total accreted gas is ejected entirely before z ̃ 1, removing primarily low angular momentum material which enriches the nearby intergalactic medium. Most recycled gas roughly conserves its angular momentum, but material ejected for long times and to large radii can gain significant angular momentum before re-accretion. These processes lower galaxy formation efficiency in addition to promoting disc formation. © 2014 The Authors.Published by Oxford University Press on behalf of the Royal Astronomical Society.


Dynamical friction in a relativistic plasma

Physical Review E 89 (2014)

OJ Pike, SJ Rose


Effects of Large-Angle Coulomb Collisions on Inertial Confinement Fusion Plasmas

Physical Review Letters 112 (2014)

AE Turrell, M Sherlock, SJ Rose


Molecular gas properties of the giant molecular cloud complexes in the arms and inter-arms of the spiral galaxy NGC 6946

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 437 (2014) 1434-1455

S Topal, E Bayet, M Bureau, TA Davis, W Walsh


Suppression of local heat flux in a turbulent magnetized intracluster medium

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 440 (2014) 1153-1164

SV Komarov, EM Churazov, AA Schekochihin, JA ZuHone