Mainz 2017 – scientific programme
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A: Fachverband Atomphysik
A 8: XUV/X-ray spectroscopy II
A 8.4: Talk
Monday, March 6, 2017, 18:15–18:30, N 2
Theoretical investigation of X-ray nonlinear Compton scattering — •Dietrich Krebs1,2, David A. Reis3, and Robin Santra1,2 — 1Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany — 2Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany — 3Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
Motivated by a recent experiment [1], we theoretically investigate the process of X-ray nonlinear Compton scattering. Our approach is based on the time-dependent Schrödinger equation for an atomic system subject to an intense X-ray pulse and explicitly accounts for the spontaneous scattering into a quantized photonic mode. To the best of our knowledge, this is the first time a time-dependent QED description has been attempted for a realistic system. We validate our implementation by calculating the linear Compton scattering signal for Helium at 500 eV photon energy and verify the dominance of the first-order A2 mechanism. Subsequently, we explore the processes underlying X-ray nonlinear Compton scattering within the same framework. In contrast to the second-order mechanism that experience with linear Compton scattering would suggest, we find that X-ray two-photon Compton scattering in the soft X-ray regime is dominated by certain third-order processes. Moreover, our calculations demonstrate that the nonlinear Compton spectrum extends to much lower energies than would be expected from analogy with the sharply peaked linear case.
[1] M. Fuchs et al., Nature Physics 11, 964-970 (2015)