title: Ultrahigh Brilliance Multi-MeV γ-Ray Beams from Nonlinear Relativistic Thomson Scattering.
abstract: We report on the generation of a narrow divergence (θ_{γ}<2.5  mrad), multi-MeV (E_{max}≈18  MeV) and ultrahigh peak brilliance (>1.8×10^{20}  photons s^{-1} mm^{-2}  mrad^{-2} 0.1% BW) γ-ray beam from the scattering of an ultrarelativistic laser-wakefield accelerated electron beam in the field of a relativistically intense laser (dimensionless amplitude a_{0}≈2). The spectrum of the generated γ-ray beam is measured, with MeV resolution, seamlessly from 6 to 18 MeV, giving clear evidence of the onset of nonlinear relativistic Thomson scattering. To the best of our knowledge, this photon source has the highest peak brilliance in the multi-MeV regime ever reported in the literature.
authors.affiliation: School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom.
authors.forename: G
authors.initials: G
authors.lastname: Sarri
authors.affiliation: School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom.
authors.forename: D J
authors.initials: DJ
authors.lastname: Corvan
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.
authors.forename: W
authors.initials: W
authors.lastname: Schumaker
authors.affiliation: The John Adams Institute for Accelerator Science, Imperial College of Science, Technology and Medicine, London SW7 2AZ, United Kingdom.
authors.forename: J M
authors.initials: JM
authors.lastname: Cole
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Di Piazza
authors.affiliation: School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Ahmed
authors.affiliation: School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Harvey
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: C H
authors.initials: CH
authors.lastname: Keitel
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.
authors.forename: K
authors.initials: K
authors.lastname: Krushelnick
authors.affiliation: The John Adams Institute for Accelerator Science, Imperial College of Science, Technology and Medicine, London SW7 2AZ, United Kingdom.
authors.forename: S P D
authors.initials: SP
authors.lastname: Mangles
authors.affiliation: The John Adams Institute for Accelerator Science, Imperial College of Science, Technology and Medicine, London SW7 2AZ, United Kingdom.
authors.forename: Z
authors.initials: Z
authors.lastname: Najmudin
authors.affiliation: Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Symes
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.
authors.forename: A G R
authors.initials: AG
authors.lastname: Thomas
authors.affiliation: Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Yeung
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: School of Mathematics and Physics, The Queen's University of Belfast, BT7 1NN Belfast, United Kingdom and Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Zepf