Highly collimated betatron radiation from a laser wakefield accelerator is a promising tool for spectroscopic measurements. Therefore, there is a requirement to create spectrometers suited to the unique properties of such a source. We demonstrate a spectrometer which achieves an energy resolution of <5 eV at 9 keV (E∕ΔE>1800) and is angularly resolving the x-ray emission allowing the reference and spectrum to be recorded at the same time. The single photon analysis is used to significantly reduce the background noise. Theoretical performance of various configurations of the spectrometer is calculated by a ray-tracing algorithm. The properties and performance of the spectrometer including the angular and spectral resolution are demonstrated experimentally on absorption above the K-edge of a Cu foil backlit by a laser-produced betatron radiation x-ray beam.

Department of Physics Lund University P O Box 118 S 22100 Lund Sweden

Institute of Physics of the ASCR ELI Beamlines 18221 Prague Czech Republic

John Adams Institute for Accelerator Science Imperial College London SW7 2AZ London United Kingdom

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X-ray spectroscopy station for sample characterization at ELI Beamlines