Narrowing of the emission angle in high-intensity Compton scattering

C. N. Harvey, A. Gonoskov, M. Marklund, and E. Wallin

Phys. Rev. A 93, 022112 – Published 16 February 2016

Abstract

We consider the emission spectrum of high-energy electrons in an intense laser field. At high intensities ( $a_{0} \sim 200$ ) we find that the QED theory predicts a narrower angular spread of emissions than the classical theory. This is due to the classical theory overestimating the energy loss of the particles, resulting in them becoming more susceptible to reflection in the laser pulse.

Received 27 July 2015

DOI:https://doi.org/10.1103/PhysRevA.93.022112

Physics Subject Headings (PhySH)

Quantum electrodynamics

Compton scattering

Atomic, Molecular & Optical

Authors & Affiliations

C. N. Harvey^1,*, A. Gonoskov^1,2,3,†, M. Marklund^1,‡, and E. Wallin^4,§

¹Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
²Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
³Lobachevsky State University of Nizhni Novgorod, Nizhny Novgorod 603950, Russia
⁴Department of Physics, Umeå University, SE-90187 Umeå, Sweden

^*christopher.harvey@chalmers.se
^†arkady.gonoskov@chalmers.se
^‡mattias.marklund@chalmers.se
^§erik.wallin@physics.umu.se

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Vol. 93, Iss. 2 — February 2016

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Figure 1
Diagrams showing the relationship between the laser momentum and the peak scattering angle of the emitted photons. (a) $a_{0} ≪ γ$ ; the peak emissions will be forward scattered relative to the laser axis. (b) $a_{0} \sim 2 γ$ defines the “center-of-mass” frame for the collision where the peak emissions will be at $90^{\circ}$ . (c) $a_{0} ≫ γ$ ; the peak emissions will be backscattered relative to the laser axis. See Ref. [21] for further details.
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Figure 2
Diagram showing how the $γ$ factor of the particle decreases due to RR losses throughout its interaction with the laser pulse. The dynamics can be roughly divided into three regimes: (i) initially $γ ≫ a (ϕ)$ ; (ii) as the particle approaches the peak field it loses energy due to RR, resulting in $γ \sim a (ϕ)$ ; (iii) after the peak field there will be a period where $γ < a (ϕ)$ .
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Figure 3
Integrated frequency spectra (left panel) and angular spectra (right panel) for the case of an electron with initial $γ_{0} = 800$ colliding with a laser of intensity $a_{0} = 200, λ = 0.8 μ m$ , and duration 30 fs. Blue line: classical. Red line: QED.
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Figure 4
Density plot showing how the electron $γ$ factor changes with time (statistical distribution generated by recording the paths of 500 QED electrons all with the same initial condition $γ_{0} = 800$ ). Parameters are $a_{0} = 200, λ = 0.8 μ m$ , and duration 30 fs. The white line shows the $γ$ factor for a classical electron.
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Figure 5
Details of the setup for a more realistic example. Top left panel: we consider a bunch of 1000 electrons randomly distributed in transverse space according to a Gaussian distribution of $5 μ m$ FWHM. Top right panel: initial energy distribution of the electron bunch. Bottom panel: plot showing the laser intensity (color scale shows $a_{0}$ ) together with the electron bunch in the $z - x$ plane. The solid black lines show how the laser waist varies as the pulse propagates (note that in the simulations the collision occurs at the origin).
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Figure 6
Emission spectrum for the realistic case ( $a_{0} = 250$ ) described in Fig. 5. The center panel shows the radiation intensity as a function of frequency and angle. This panel is split into two, the top half showing the emissions for the QED simulation and the bottom half the classical. The right-hand panel shows the total angular rate summed over all frequencies (both classical and QED for all angles), and the bottom panel the total frequency rate summed over all angles. Red lines: QED. Blue lines: classical.
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Physical Review A

covering atomic, molecular, and optical physics and quantum information

Narrowing of the emission angle in high-intensity Compton scattering

C. N. Harvey, A. Gonoskov, M. Marklund, and E. Wallin

Phys. Rev. A 93, 022112 – Published 16 February 2016

Abstract

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Physical Review A

covering atomic, molecular, and optical physics and quantum information

Narrowing of the emission angle in high-intensity Compton scattering

C. N. Harvey, A. Gonoskov, M. Marklund, and E. Wallin

Phys. Rev. A 93, 022112 – Published 16 February 2016

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

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