Since the first lasing of the Linac Coherent Light Source in the hard X-ray spectral region and FLASH and FERMI in the soft X-ray region, many other X-ray Free-Electron Lasers (X-FELs) have been designed, built and commissioned, in Asia, USA and Europe to explore atomic and molecular science at the Ångström-femtosecond space and time scales. Great progress has been made in improving their performance and extending the capabilities of X-FELs, improving the peak power and longitudinal coherence, generating pulses with femtosecond and shorter duration. At the same time, the X-FEL user community has made tremendous progress in developing experimental techniques that exploit the unique properties of X-FELs to explore atomic and molecular systems of interest to physics, chemistry, biology and material sciences, at the Ångström-femtosecond space and time scales. After the early proof-of-principle experiments, FEL-based X-ray science has been growing at a rapid rate, continuously adding new technical and experimental capabilities. As a result, our knowledge of atomic and molecular science has been largely extended. New results, possible only using X-ray FELs, have been obtained also in materials science and high energy density science, including phenomena relevant to the state of matter in the interior of planets and stars.
Even if great progress has been made, there is still much to be accomplished, and the potential for discovery with X-FELs is still largely unexplored. To take advantage of the unmatched flexibility of X-FELs, the next generation of scientists will have to be well versed in both particle beams/FEL physics and X-ray photon science.
The Italian Physical Society International School of Physics “Enrico Fermi”, on “Physics of and Science with X-ray Free Electron Lasers”, will be the seed of this approach to X-FEL based science. The multidisciplinary program includes basic accelerator and FEL physics, as well as an introduction to the main research topics in X-FEL based Biology, Atomic Molecular Optical Science, Material Sciences, High Energy Density Physics and Chemistry. The lectures presented at the school will introduce graduate students and young scientists to this fast growing and exciting scientific area and help bridge the gap between accelerator/FEL physicists and scientists working in all these disciplines, encouraging collaboration across different fields of X-FEL based science.
The lectures start with a discussion of the physics and technology of X-ray free-electron lasers, then cover the interaction of X-ray with matter and results obtained in different fields using X-ray FELs, including some very recent work, giving a wide view of the research being actively done.
We wish to express our gratitude to the Italian Physical Society, SLAC National Accelerator Laboratory, Sincrotrone Trieste, European X-FEL for supporting the course. Our gratitude and thanks go to the staff of the Varenna School for their help and assistance during the course and our memorable stay in Varenna.
J. Hastings, C. Pellegrini and A. Marinelli