Anomalous nonlinear X-ray Compton scattering

Matthias Fuchs, Mariano Trigo, Jian Chen, Shambhu Ghimire, Sharon Shwartz, Michael Kozina, Mason Jiang, Thomas Henighan, Crystal Bray, Georges Ndabashimiye, Philip H. Bucksbaum, Yiping Feng, Sven Herrmann, Gabriella A. Carini, Jack Pines, Philip Hart, Christopher Kenney, Serge Guillet, Sébastien Boutet, Garth J. WilliamsMarc Messerschmidt, M. Marvin Seibert, Stefan Moeller, Jerome B. Hastings, David A. Reis

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


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 4×10 20 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.

Original languageEnglish (US)
Pages (from-to)964-970
Number of pages7
JournalNature Physics
Issue number11
StatePublished - Nov 3 2015
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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