UK XFEL - Scientific Case Project
22 May 2019



The UK XFEL Conceptual Design Report is building on the Science Case to explore options for UK researchers to have access to next-generation XFEL capabilities.




UK XFEL - Sc​​​ience Case

The comprehensive, peer-reviewed, science case for a UK XFEL addresses:

  • Over the coming decades how will the technological and scientific opportunities 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?  

A formal process to develop the science case for a UK based X-ray Free Electron Laser (UK-XFEL), was launched by STFC at the Royal Society (more details of this event can be found here) in 2019. The resulting draft formed the basis of a consultation with the scientific community and comments received were incorporated into a final version of the science case, published in late 2020.

The Science Case clearly sets out the important future opportunities and strategic need for UK science to have access to such a capability over the coming decades. It proposed a dedicated UK based next generation XFEL to achieve this. 

Download the science case in full, or read the executive summary.

UK XFEL - Conceptual Design Report

The next phase of UK XFEL is to produce a 'UK XFEL Conceptual Design Report' (CDR).

To deliver the world leading science highlighted by the Science Case, UK academics will need access to next generation XFEL capability, the key question which the CDR aims to answer is 'how best to achieve this?' To do that the CDR will fully evaluate different options to enable UK researchers' access to next generation XFEL capability, including their costs, benefits, risks and sustainability.

The conceptual design and options to build a UK XFEL will be investigated during this CDR, along with other options, including making significant investments into overseas XFELs to enhance thei​r current capabilities as part of a strategic development to create a next generation XFEL.

The CDR will enable the UK to make an informed decision on how access to next generation XFELs for UK researchers should best be achieved. The next phase for UK XFEL will be led by ASTeC with significant input also from the CLF and Technology Department, as well as from colleagues across the wider light source and accelerator communities.

It is currently planned that the science case will also undergo a refresh during this period along with research and development into new technologies required to deliver a sustainable next generation XFEL. We therefore expect during this period to continue to work closely with academia as well as our colleagues at other institutions around the world.

UK XFEL - Scien​ce 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 F​​​EL

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.

UK XFEL  - Communit​y consultations

In 2019-2021 a series of consultations took place with the UK and International user community, exploring the appetite for a next-generation XFEL facility.

Read more about the consultations here.

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)