Laser assisted Compton scattering of X-ray photons

TL;DR

This paper investigates laser-assisted Compton scattering of X-ray photons, revealing complex spectral features, polarization effects, and providing analytic formulas, with potential for experimental validation at major X-ray facilities.

Contribution

It introduces a detailed analysis of laser-assisted Compton scattering, including the formation of side-lines and polarization rotation, with an analytic expression for the plateau width.

Findings

Main Klein-Nishina line with side-lines forming a broad plateau

Frequency-dependent polarization rotation of scattered X-rays

Analytic formula for the width of the scattering plateau

Abstract

The Compton scattering of X-ray photons, assisted by a short intense optical laser pulse, is discussed. The differential scattering cross section reveals the interesting feature that the main Klein-Nishina line is accompanied by a series of side-lines forming a broad plateau where up to ${\cal O} (10^3)$ laser photons participate simultaneously in a single scattering event. An analytic formula for the width of the plateau is given. Due to the non-linear mixing of X-ray and laser photons a frequency dependent rotation of the polarization of the final state X-ray photons relative to the scattering plane emerges. A consistent description of the scattering process with short laser pulses requires to work with X-ray pulses. An experimental investigation can be accomplished, e.g., at LCLS or the European XFEL in the near future.