X-ray free electron lasers (XFELs) generate sequences of ultra-short, spatially coherent pulses of x-ray radiation. We propose the diffraction focusing spectrometer (DFS), which is able to measure the whole energy spectrum of the radiation of a single XFEL pulse with an energy resolution of ΔE/E≈2×10−6. This is much better than for most modern x-ray spectrometers. Such resolution allows one to resolve the fine spectral structure of the XFEL pulse. The effect of diffraction focusing occurs in a single crystal plate due to dynamical scattering, and is similar to focusing in a Pendry lens made from the metamaterial with a negative refraction index. Such a spectrometer is easier to operate than those based on bent crystals. We show that the DFS can be used in a wide energy range from 5 keV to 20 keV.
@article{arxiv.1211.3723,
title = {Spectrometer for Hard X-Ray Free Electron Laser Based on Diffraction Focusing},
author = {V. G. Kohn and O. Y. Gorobtsov and I. A. Vartanyants},
journal= {arXiv preprint arXiv:1211.3723},
year = {2013}
}