Publications


A current-driven electromagnetic mode in sheared and toroidal configurations

PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 035011

I Pusztai, PJ Catto, FI Parra, M Barnes


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

Plasma Physics and Controlled Fusion 56 (2014)

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

New acceleration technology is mandatory for the future elucidation of fundamental particles and their interactions. A promising approach is to exploit the properties of plasmas. Past research has focused on creating large-amplitude plasma waves by injecting an intense laser pulse or an electron bunch into the plasma. However, the maximum energy gain of electrons accelerated in a single plasma stage is limited by the energy of the driver. Proton bunches are the most promising drivers of wakefields to accelerate electrons to the TeV energy scale in a single stage. An experimental program at CERN - the AWAKE experiment - has been launched to study in detail the important physical processes and to demonstrate the power of proton-driven plasma wakefield acceleration. Here we review the physical principles and some experimental considerations for a future proton-driven plasma wakefield accelerator. © 2014 IOP Publishing Ltd.


Turbulent amplification of magnetic fields in laboratory laser-produced shock waves

NATURE PHYSICS 10 (2014) 520-524

J Meinecke, HW Doyle, F Miniati, AR Bell, R Bingham, R Crowston, RP Drake, M Fatenejad, M Koenig, Y Kuramitsu, CC Kuranz, DQ Lamb, D Lee, MJ MacDonald, CD Murphy, H-S Park, A Pelka, A Ravasio, Y Sakawa, AA Schekochihin, A Scopatz, P Tzeferacos, WC Wan, NC Woolsey, R Yurchak, B Reville, G Gregori


Equivalence of two independent calculations of the higher order guiding center Lagrangian

PHYSICS OF PLASMAS 21 (2014) ARTN 104506

FI Parra, I Calvo, JW Burby, J Squire, H Qin


Resolving ultrafast heating of dense cryogenic hydrogen.

Physical review letters 112 (2014) 105002-

U Zastrau, P Sperling, M Harmand, A Becker, T Bornath, R Bredow, S Dziarzhytski, T Fennel, LB Fletcher, E Förster, S Göde, G Gregori, V Hilbert, D Hochhaus, B Holst, T Laarmann, HJ Lee, T Ma, JP Mithen, R Mitzner, CD Murphy, M Nakatsutsumi, P Neumayer, A Przystawik, S Roling, M Schulz, B Siemer, S Skruszewicz, J Tiggesbäumker, S Toleikis, T Tschentscher, T White, M Wöstmann, H Zacharias, T Döppner, SH Glenzer, R Redmer

We report on the dynamics of ultrafast heating in cryogenic hydrogen initiated by a ≲300  fs, 92 eV free electron laser x-ray burst. The rise of the x-ray scattering amplitude from a second x-ray pulse probes the transition from dense cryogenic molecular hydrogen to a nearly uncorrelated plasmalike structure, indicating an electron-ion equilibration time of ∼0.9  ps. The rise time agrees with radiation hydrodynamics simulations based on a conductivity model for partially ionized plasma that is validated by two-temperature density-functional theory.


Actions, angles and frequencies for numerically integrated orbits

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 441 (2014) 3284-3295

JL Sanders, J Binney


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


Non-linear mirror instability

Monthly Notices of the Royal Astronomical Society: Letters 447 (2014) L45-L49

F Rincon, F Rincon, AA Schekochihin, AA Schekochihin, SC Cowley, SC Cowley

© 2014 The Author. Slow dynamical changes in magnetic-field strength and invariance of the particles' magnetic moments generate ubiquitous pressure anisotropies in weakly collisional, magnetized astrophysical plasmas. This renders them unstable to fast, small-scale mirror and firehose instabilities, which are capable of exerting feedback on the macroscale dynamics of the system. By way of a new asymptotic theory of the early non-linear evolution of the mirror instability in a plasma subject to slow shearing or compression, we show that the instability does not saturate quasi-linearly at a steady, low-amplitude level. Instead, the trapping of particles in small-scale mirrors leads to non-linear secular growth of magnetic perturbations, δB/Bt2/3. Our theory explains recent collisionless simulation results, provides a prediction of the mirror evolution in weakly collisional plasmas and establishes a foundation for a theory of non-linear mirror dynamics with trapping, valid up to δB/B = O(1).


AMS-02 data confronts acceleration of cosmic ray secondaries in nearby sources

ArXiv (2014)

P Mertsch, S Sarkar

We revisit the model proposed earlier to account for the observed increase in the positron fraction in cosmic rays with increasing energy, in the light of new data from the Alpha Magnetic Spectrometer (AMS-02) experiment. The model accounts for the production and acceleration of secondary electrons and positrons in nearby supernova remnants which results in an additional, harder component that becomes dominant at high energies. By fitting this to AMS-02 data we can calculate the expected concomitant rise of the boron-to-carbon ratio, as well as of the fraction of antiprotons. If these predictions are confirmed by the forthcoming AMS-02 data it would conclusively rule out all other proposed explanations, in particular dark matter annihilations or decays.


On the maximum energy of shock-accelerated cosmic rays at ultra-relativistic shocks

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 439 (2014) 2050-2059

B Reville, AR Bell


Observation of the cosmic-ray shadow of the Moon with IceCube

ArXiv (2013)

I Collaboration, MG Aartsen, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, JJ Beatty, S Bechet, JB Tjus, K-H Becker, M Bell, ML Benabderrahmane, S BenZvi, J Berdermann, P Berghaus, D Berley, E Bernardini, A Bernhard, D Bertrand, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, S Bohaichuk, C Bohm, D Bose, S Böser, O Botner, L Brayeur, H-P Bretz, AM Brown, R Bruijn, J Brunner, M Carson, J Casey, M Casier, D Chirkin, A Christov, B Christy, K Clark, F Clevermann, S Coenders, S Cohen, DF Cowen, AHC Silva, M Danninger, J Daughhetee, JC Davis, CD Clercq, SD Ridder, P Desiati, MD With, T DeYoung, JC Díaz-Vélez, M Dunkman, R Eagan, B Eberhardt, J Eisch, RW Ellsworth, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, R Franke, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, JA Goodman, D Góra, DT Grandmont, D Grant, A Groß, C Ha, AH Ismail, P Hallen, A Hallgren, F Halzen, K Hanson, D Heereman, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, K Jagielski, GS Japaridze, K Jero, O Jlelati, B Kaminsky, A Kappes, T Karg, A Karle, JL Kelley, J Kiryluk, F Kislat, J Kläs, SR Klein, J-H Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, K Krings, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leute, J Lünemann, J Madsen, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Mészáros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, L Paul, JA Pepper, CPDL Heros, C Pfendner, D Pieloth, E Pinat, N Pirk, J Posselt, PB Price, GT Przybylski, L Rädel, M Rameez, K Rawlins, P Redl, R Reimann, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, H-G Sander, M Santander, S Sarkar, K Schatto, M Scheel, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, A Schönwald, A Schukraft, L Schulte, O Schulz, D Seckel, Y Sestayo, S Seunarine, C Sheremata, MWE Smith, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, A Tepe, S Ter-Antonyan, G Tešić, S Tilav, PA Toale, S Toscano, M Usner, DVD Drift, NV Eijndhoven, AV Overloop, JV Santen, M Vehring, M Voge, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, R Wasserman, C Weaver, M Wellons, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, C Xu, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, M Zoll

We report on the observation of a significant deficit of cosmic rays from the direction of the Moon with the IceCube detector. The study of this "Moon shadow" is used to characterize the angular resolution and absolute pointing capabilities of the detector. The detection is based on data taken in two periods before the completion of the detector: between April 2008 and May 2009, when IceCube operated in a partial configuration with 40 detector strings deployed in the South Pole ice, and between May 2009 and May 2010 when the detector operated with 59 strings. Using two independent analysis methods, the Moon shadow has been observed to high significance (> 6 sigma) in both detector configurations. The observed location of the shadow center is within 0.2 degrees of its expected position when geomagnetic deflection effects are taken into account. This measurement validates the directional reconstruction capabilities of IceCube.


How do galaxies build up their spin in the cosmic web?

ArXiv (2014)

C Welker, Y Dubois, J Devriendt, C Pichon, S Peirani

Using the Horizon-AGN simulation we find a mass dependent spin orientation trend for galaxies: the spin of low-mass, rotation-dominated, blue, star-forming galaxies are preferentially aligned with their closest filament, whereas high-mass, velocity dispersion- supported, red quiescent galaxies tend to possess a spin perpendicular to these filaments. We explore the physical mechanisms driving galactic spin swings and quantify how much mergers and smooth accretion re-orient them relative to their host filaments and impact their shape. In particular, we analyze the effect of dispersion and morphology of galaxies and discuss potential tracers for prospective surveys.


Intrinsic momentum transport in up-down asymmetric tokamaks

PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 095014

J Ball, FI Parra, M Barnes, W Dorland, GW Hammett, P Rodrigues, NF Loureiro


Synchrotron radiation, pair production, and longitudinal electron motion during 10-100 PW laser solid interactions

PHYSICS OF PLASMAS 21 (2014) ARTN 033108

CS Brady, CP Ridgers, TD Arber, AR Bell


REVIEW OF PARTICLE PHYSICS Particle Data Group

CHINESE PHYSICS C 38 (2014) ARTN 090001

KA Olive, K Agashe, C Amsler, M Antonelli, J-F Arguin, DM Asner, H Baer, HR Band, RM Barnett, T Basaglia, CW Bauer, JJ Beatty, VI Belousov, J Beringer, G Bernardi, S Bethke, H Bichsel, O Biebel, E Blucher, S Blusk, G Brooijmans, O Buchmueller, V Burkert, MA Bychkov, RN Cahn, M Carena, A Ceccucci, A Cerri, D Chakraborty, M-C Chen, RS Chivukula, K Copic, G Cowan, O Dahl, G D'Ambrosio, T Damour, D de Florian, A de Gouvea, T DeGrand, P de Jong, G Dissertori, BA Dobrescu, M Doser, M Drees, HK Dreiner, DA Edwards, S Eidelman, J Erler, VV Ezhela, W Fetscher, BD Fields, B Foster, A Freitas, TK Gaisser, H Gallagher, L Garren, H-J Gerber, G Gerbier, T Gershon, T Gherghetta, S Golwala, M Goodman, C Grab, AV Gritsan, C Grojean, DE Groom, M Grunewald, A Gurtu, T Gutsche, HE Haber, K Hagiwara, C Hanhart, S Hashimoto, Y Hayato, KG Hayes, M Heffner, B Heltsley, JJ Hernandez-Rey, K Hikasa, A Hoecker, J Holder, A Holtkamp, J Huston, JD Jackson, KF Johnson, T Junk, M Kado, D Karlen, UF Katz, SR Klein, E Klempt, RV Kowalewski, F Krauss, M Kreps, B Krusche, YV Kuyanov, Y Kwon, O Lahav, J Laiho, P Langacker, A Liddle, Z Ligeti, C-J Lin, TM Liss, L Littenberg, KS Lugovsky, SB Lugovsky, F Maltoni, T Mannel, AV Manohar, WJ Marciano, AD Martin, A Masoni, J Matthews, D Milstead, P Molaro, K Moenig, F Moortgat, MJ Mortonson, H Murayama, K Nakamura, M Narain, P Nason, S Navas, M Neubert, P Nevski, Y Nir, L Pape, J Parsons, C Patrignani, JA Peacock, M Pennington, ST Petcov, A Piepke, A Pomarol, A Quadt, S Raby, J Rademacker, G Raffelt, BN Ratcliff, P Richardson, A Ringwald, S Roesler, S Rolli, A Romaniouk, LJ Rosenberg, JL Rosner, G Rybka, CT Achrajda, Y Sakai, GP Salam, S Sarkar, F Sauli, O Schneider, K Scholberg, D Scott, V Sharma, SR Sharpe, M Silari, T Sjostrand, P Skands, JG Smith, GF Smoot, S Spanier, H Spieler, C Spiering, A Stah, T Stanev, SL Stone, T Sumiyoshi, MJ Sphers, F Takahashi, M Tanabashi, J Terning, L Tiator, M Titov, NP Tkachenko, NA Tornqvist, D Tovey, G Valencia, G Venanzoni, MG Vincter, P Vogel, A Vogt, SP Wakely, W Walkowiak, CW Walter, DR Ward, G Weiglein, DH Weinberg, EJ Weinberg, M White, LR Wiencke, CC Woh, L Wofenstein, J Womersley, CL Woody, RL Workman, A Yamamoto, W-M Yao, GP Zeller, OV Zenin, J Zhang, R-Y Zhu, F Zimmermann, PA Zyla, G Harper, VS Lugovsky, P Schaffner, PD Grp


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.


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


FINGERPRINTS OF GALACTIC LOOP I ON THE COSMIC MICROWAVE BACKGROUND

ASTROPHYSICAL JOURNAL LETTERS 789 (2014) ARTN L29

H Liu, P Mertsch, S Sarkar


Producing bright X-rays for imaging applications using a laser wakefield accelerator

Optics InfoBase Conference Papers (2014)

SPD Mangles, MS Bloom, J Bryant, JM Cole, A Döpp, S Kneip, H Nakamura, K Poder, MJV Streeter, J Wood, Z Najmudin, R Bendoyro, J Jiang, NC Lopes, C Russo, O Cheklov, O Ertel, S Hawkes, CJ Hooker, D Neely, PA Norreys, PP Rajeev, DR Rusby, RHH Scott, DR Symes, J Holloway, M Wing, JF Seely

We report on the generation of bright multi-keV betatron X-ray radiation using a GeV laser wakefield accelerator and investigate the use of these X-rays for various imaging applications. © 2014 Optical Society of America.


When omnigeneity fails

ArXiv (2014)

FI Parra, I Calvo, JL Velasco, JA Alonso

A generic non-symmetric magnetic field does not confine magnetized charged particles for long times due to secular magnetic drifts. Stellarator magnetic fields should be omnigeneous (that is, designed such that the secular drifts vanish), but perfect omnigeneity is technically impossible. There always are small deviations from omnigeneity that necessarily have large gradients. The amplification of the energy flux caused by a deviation of size $\epsilon$ is calculated and it is shown that the scaling with $\epsilon$ of the amplification factor can be as large as linear. In opposition to common wisdom, most of the transport is not due to particles trapped in ripple wells, but to the perturbed motion of particles trapped in the omnigeneous magnetic wells around their bounce points.