Speaker
Thomas George Blackburn
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.2018.pdf
Launching electromagnetic cascades in high-intensity laser fields
T. G. Blackburn1 , A. Ilderton2 , S. P. D. Mangles3 , C. D. Murphy4 , C. P. Ridgers4 , M. Marklund1
1 Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
2 Centre for Mathematical Sciences, Plymouth University, Plymouth, UK
3 The John Adams Institute for Accelerator Science, Imperial College London, London, UK
4 York Plasma Institute, Department of Physics, University of York, York, UK
A cascade of photon emission and electron-positron pair creation is launched when a high-
energy electron or photon traverses a region of sufficiently strong electromagnetic field, such as
at the focus of a high-power laser. Cascades in the highly nonlinear regime, where the laser
strength parameter a0 1 and the quantum parameter χ ∼ 1, are relevant to the study of
astrophysical plasmas, such as in pulsar magnetospheres, and will be a ubiquitous feature of
high-intensity experiments at the next generation of laser facilities. When combined with the
ultrarelativistic, ultrashort electron beams available from laser-wakefield acceleration, today’s
high-intensity lasers have the capability to probe this regime, where the recoil from emission of
multiple photons (radiation reaction) dominates the electron dynamics [1, 2].
If the fields are strong enough that χ ∼ 1, the photons will produce electron-positron pairs,
and the daughter electrons and positrons will lose energy to secondary radiation. We discuss
the prospects for observation of such a cascade in two experimental geometries: one in which a
multi-GeV, laser-wakefield accelerated electron beam collides directly with a laser pulse, pro-
ducing photons via nonlinear Compton scattering [3]; and one in which the electron beam first
collides with a high-Z foil, producing GeV photons via bremsstrahlung that go on to collide
with a high-intensity laser pulse [4].
References
[1] J. M. Cole et al., Experimental Evidence of Radiation Reaction in the Collision of a High-Intensity Laser
Pulse with a Laser-Wakefield Accelerated Electron Beam, Phys. Rev. X 8, 011020 (2018)
[2] K. Poder et al., Evidence of strong radiation reaction in the field of an ultra-intense laser, arXiv:1709:01861
(2017)
[3] T. G. Blackburn, A. Ilderton, C. D. Murphy and M. Marklund, Scaling laws for positron production in laser–
electron-beam collisions, Phys. Rev. A 96, 022128 (2017)
[4] T. G. Blackburn and M. Marklund, Nonlinear Breit-Wheeler pair creation with bremsstrahlung γ rays,
arXiv:1802.06612 (2018)
