Anomalous nonlinear X-ray Compton scattering

Authors

• Matthias Fuchs, University of Nebraska-LincolnFollow
• Mariano Trigo, SLAC National Accelerator LaboratoryFollow
• Jian Chen, SLAC National Accelerator LaboratoryFollow
• Shambhu Ghimire, SLAC National Accelerator LaboratoryFollow
• Sharon Shwartz, Bar Ilan UniversityFollow
• Michael Kozina, SLAC National Accelerator LaboratoryFollow
• Mason Jiang, SLAC National Accelerator Laboratory
• Thomas Henighan, SLAC National Accelerator LaboratoryFollow
• Crystal Bray, SLAC National Accelerator LaboratoryFollow
• Georges Ndabashimiye, SLAC National Accelerator Laboratory
• Philip H. Bucksbaum, SLAC National Accelerator LaboratoryFollow
• Yiping Feng, SLAC National Accelerator LaboratoryFollow
• Sven Herrmann, SLAC National Accelerator LaboratoryFollow
• Gabriella A. Carini, SLAC National Accelerator LaboratoryFollow
• Jack Pines, SLAC National Accelerator Laboratory
• Philip Hart, SLAC National Accelerator Laboratory
• Christopher Kenney, SLAC National Accelerator LaboratoryFollow
• Serge Guillet, SLAC National Accelerator LaboratoryFollow
• Sébastien Boutet, SLAC National Accelerator LaboratoryFollow
• Garth J. Williams, SLAC National Accelerator Laboratory
• Marc Messerschmidt, SLAC National Accelerator LaboratoryFollow
• M. Marvin Seibert, SLAC National Accelerator Laboratory
• Stefan Moeller, SLAC National Accelerator LaboratoryFollow
• Jerome B. Hastings, SLAC National Accelerator LaboratoryFollow
• David A. Reis, SLAC National Accelerator LaboratoryFollow

Document Type

Article

Date of this Version

2015

Citation

Published in Nature Physics 11 (2015), pp 964–970. doi 10.1038/nphys3452

Comments

© 2015 Macmillan Publishers Limited. Used by permission.

Abstract

X-ray scattering is typically used as a weak linear atomic-scale probe of matter. At high intensities, such as produced at free-electron lasers, nonlinearities can become important, and the probe may no longer be considered weak. Here we report the observation of one of the most fundamental nonlinear X-ray–matter interactions: the concerted nonlinear Compton scattering of two identical hard X-ray photons producing a single higher-energy photon. The X-ray intensity reached 4 × 10²⁰ W cm⁻², corresponding to an electric field well above the atomic unit of strength and within almost four orders of magnitude of the quantum-electrodynamic critical field. We measure a signal from solid beryllium that scales quadratically in intensity, consistent with simultaneous non-resonant two-photon scattering from nearly-free electrons. The high-energy photons show an anomalously large redshift that is incompatible with a free-electron approximation for the ground-state electron distribution, suggesting an enhanced nonlinearity for scattering at large momentum transfer.