Superradiant Parametric Mössbauer Radiation Source

Future applications of the spectrally narrow x-ray resonances in Mössbauer nuclei require x-ray sources with exceptionally high peak and average spectral flux. Here, we introduce a superradiant parametric Mössbauer radiation (SPMR) source, which utilizes the scattering of spatially microstructured electron bunches produced in x-ray free-electron laser (XFEL) accelerators on crystals. The spatial structuring leads to a coherent add-up of the radiation from different electrons, thereby enhancing the Mössbauer radiation by many orders of magnitude. We find that the performance is optimized at qualitatively different operation conditions than considered so far. For a focused electron beam with parameters based on the European XFEL facility, our approach predicts the generation of more than 900 SPMR photons per pulse within one linewidth of the _{26}^{57}Fe Mössbauer resonance. This opens up new opportunities for precision metrology, and for hard x-ray pump-probe spectroscopy techniques via the parallel use of the bunched XFEL electron and photon beams.