Author: Shvyd'ko, Yu.
Paper Title Page
MOP086 Novel Opportunities for Sub-meV Inelastic X-Ray Scattering Experiments at High-Repetition Rate Self-seeded XFELs 257
  • O.V. Chubar
    BNL, Upton, Long Island, New York, USA
  • G. Geloni, A. Madsen
    XFEL. EU, Hamburg, Germany
  • V. Kocharyan, E. Saldin, S. Serkez
    DESY, Hamburg, Germany
  • Yu. Shvyd'ko
    ANL, Argonne, Ilinois, USA
  • J. Sutter
    DLS, Oxfordshire, United Kingdom
  Inelastic x-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25/nm spectral and momentum Transfer resolutions, respectively*. However, further improvements down to 0.1 meV and 0.02/nm are required to close the gap in energy-momentum space between high and low frequency probes. We Show that this goal can be achieved by further improvements in x-ray optics and by increasing the spectral flux of the incident x-ray pulses. UHRIX performs best at energies from 5 to 10 keV, where a combination of self-seeding and undulator tapering at the SASE2 beamline of the European XFEL promises up to a hundred-fold increase in average spectral flux compared to nominal SASE pulses at saturation, or three orders of magnitude more than possible with storage-ring based radiation sources. Wave-optics propagation shows that about 7·1012 ph/s in a 90-microeV bandwidth can be achieved on the sample. This will provide unique new possibilities for IXS. Extended information about our work can be found in**.
* Y. Shvyd'ko et al., Nature Communications 5:4219 (2014).
** O. Chubar et al., ‘Novel opportunities for sub-meV inelastic X-ray scattering at high-repetition rate self-seeded X-ray free-electron lasers',, DESY 15-140, (2015).
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Progress Towards an X-ray FEL Oscillator  
  • K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, S. Stoupin
    ANL, Argonne, Ilinois, USA
  • J. Arthur, Y. Ding, W.M. Fawley, J.C. Frisch, J.B. Hastings, Z. Huang, J. Krzywinski, G. Marcus, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  Funding: Work at ANL supported under US Department of Energy contract DE-AC02-76SF00515 and at SLAC by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO2-O6CH11357
Issues and progress in R&D toward realizing an X-ray FEL oscillator will be discussed, including electron injector optimization, X-ray power density evolution on Bragg crystals throughout the lasing process, experimental efforts for testing radiation damage, evaluating the performance of compound refractive lenses (CRLs) as the focusing elements, and the basic considerations for mechanical layout. These will be discussed in the context of a concrete implementation scheme [*] using the 4 GeV superconducting linac to be constructed at the LCLS-II. Time-dependent simulations of harmonic XFELO performance is discussed in another contribution to this conference by Zemella, et al.
[*] T. J. Maxwell et al., Feasibility study for an X-ray free electron laser oscillator, IPAC 2015, Richmond, Virginia, USA
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