UK XFEL - Scientific Case Project
22 May 2019







Science Case - Final version published

STFC formally launched the process to create an updated science case for a UK based X-ray Free Electron Laser (UK-XFEL) in July 2019 at the Royal Society (more details of this event can be found here). The resulting draft document formed the basis of a consultation with the scientific community and comments received during this time have now been incorporated into a final version published in October. This final version of the science case was subject to a formal independent review in November.

​The science case can be downloaded in Full, or just the Executive Summary  (Final version published 5th October 2020)​.

​​The science case seeks to address:

  • Over the coming decades how will the technological and scientific opport​unities enabled by XFELs develop?
  • What specific impact might there be from a UK machine aimed at offering new capabilities and adding to the capacity available internationally.​ 

STFC, Prof Marangos and the Science Team are still actively soliciting feedback, Please send any comments or thoughts to

April 2021 - ​A community support letter for the “UK XFEL” project

To explore the UK and International community appetite for a next generation XFEL we are conducting a survey to gather information and sample support for the UK XFEL project (which seeks to deliver such next generation capability). You are invited to complete a survey which includes an opportunity to join a community endorsement that reads as follows:

“X-ray free electron lasers (XFELS) have emerged as important and wide-ranging tools for advanced science over the last decade. Their impact has been extensive (from catalysis and energy research to structural biology and laboratory astrophysics) and has opened-up a new era in research in structural dynamics. In the UK and around the world significant numbers of scientists have begun to engage with these opportunities, and many more are hoping to do so as the capabilities are developed, and as capacity grows so that it becomes easier to secure access.

The UK XFEL Science Case ( examines the transformative scientific opportunities that will be created with a Next Generation XFEL i.e. one that can deliver near transform limited pulses, high reproducibility, and synchronised to a wide range of external beams (e.g. lasers, THz and electrons) all delivered at a high repetition rate with a pulse structure matching state-of-the-art sample delivery and detector technologies. We strongly endorse this scientific vision, and fully support the next stage in the efforts to ensure that there is an overall capacity increase and that these new capabilities can be made available over the next decade for advancing science and technology."

​The survey link is:

​UK XFEL - Scientific Case Project - 2019-2020 User Consultation exercise

This initial phase of the consultation process has now concluded. However details of the original science meetings including presentations by the various speakers from academia and industry can still be found here: UK XFEL - Scientific Case Project - 2019 User Consultation exercise

​​UK XFEL - Science Opportunities

High brightness ultra-fast x-ray pulses from an X-ray FEL allow the simultaneous imaging of atomic scale structure, electronic state and dynamics in a material. There is no other technology that can do that. The unique science opportunities that these machines can open-up include:

  • Access to structural dynamics: Dynamical phenomena can be probed on a time scale down to femtoseconds thus covering electronic dynamics, lattice dynamics and chemical bonds breaking/forming. This capability can be applied to: chemical reactions (for optimisation of e.g. catalysis, water-splitting, hydrogen storage mechanisms), energy materials (for optimisation of photovoltaics, battery technology), engineering materials (to understand/ mitigate mechanisms of corrosion, radiation damage, shock damage), and biochemistry (to unravel photosynthesis, light sensitive protein activity).

  • New modes of nanoscopic imaging: These can be used for seeing the nanoscopic arrangements in nanotechnology and life-sciences free from radiation damage and adverse effects of sample preparation (e.g. in situ imaging of the function of biomolecular assemblies at operating temperature).

  • Access to transient states: Matter can be probed under conditions which are only transiently achieved, such as: extreme pressure, high E & B fields, laser dressing and high energy density (important to astrophysics, planetary science, geophysics, defence and quantum materials).

  • The potential to capture rare events: In physical, chemical and biological systems critical processes often proceed through rare events arising from intrinsic fluctuations and an XFEL opens the possibility to directly visualize these (e.g. can capture natural chemical/biochemical reactions in the act).

These are broadly applicable capabilities that provide a completely new window into matter and dynamics with impact across a wide landscape of science and technology. They will be used alongside other modalities (optical, neutron, cryo EM, UED, synchrotron X-ray, NMR etc.) to increase our abilities to probe and control matter.

A unique UK X-ray FEL

An XFEL consists of a linear electron accelerator and undulators to generate very bright and ultra-short pulses of X-rays via the self-amplified spontaneous emission (SASE) process.  What is now needed is a machine with much better control of the X-ray properties than with the current generation of intrinsically noisy SASE machines. This will enable new classes of measurements. Building one of these in the UK would make us an international centre for the next generation of X-ray FEL science. Building a state-of-the-art SASE machine with a unique combination of end-station capability could also lead to compelling new science. The UK could also continue to invest substantially in the international array of X-ray FELs and use this as leverage to ensure those facilities, especially exciting new projects like Euro XFEL and LCLS II HE, are steered in directions that match best our science needs.

Contact our Science Team for further information:​

  • Matter in extreme conditions: Andy Higginbotham (York), Andy Comley (AWE), Malcolm McMahon (Edinburgh), Justin Wark (Oxford)

  • Nano/Quantum materials: Ian Robinson (UCL/Brookhaven), Anna Regoutz (IC), Simon Wall (ICFO)

  • Materials: David Rugg (RR), Sven Schroeder (Leeds), David Dye (IC)

  • Life sciences: Allen Orville (DLS), Jasper van Thor (IC)

  • Chemical sciences: Julia Weinstein (Sheffield), Russell Minns (Soton), Sofia Diaz-Moreno (DLS), Tom Penfold (Newcastle)

  • Ultrafast physics: Adam Kirrander (Edinburgh), Amelle Zair (KCL)
Contact: Green, James (STFC,RAL,CLF)