Workshop on Emerging Ultrafast Diffraction facilities in the UK: 'LUXD, EPAC and RUEDI'

Date: Thursday 20 November 2025

Location: Central Laser Facility, Rutherford Appleton Laboratory Visitor Centre (Building R112),
Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX

Register at https://indico.stfc.ac.uk/event/1535

Summary

The Imperial College Laboratory for Ultrafast X-ray Diffraction (LUXD), The Extreme Photonics Applications Centre (EPAC) and The Relativistic Ultrafast Electron Diffraction and Imaging facility (RUEDI) are currently in the various stages of design, building and commissioning and will provide complementary capabilities for ultrafast diffraction studies of structural dynamics in the UK.

LUXD, EPAC and RUEDI are jointly organising a one-day workshop to engage with the UK community working in the area of ultrafast diffraction. The aim of the workshop is to present these new facilities to the UK community and discuss their capabilities, to identify technical requirements and scientific applications, to stimulate collaboration and develop the future user communities.

Programme

The outline for the workshop is as follows:

Summary of diffraction facilities

LUXD

The Imperial College Laboratory for Ultrafast X-ray Diffraction (LUXD) is a laser driven plasma hard X-ray source, producing an incoherent line emission pulse train of Cu-Kα radiation at 1.542 Å wavelength and ~100 fs duration. Taking advantage of novel OPCPA technology the mid-infrared laser driver is at 5µm wavelength, 45 fs, 1  KHz repetition rate and 10 mJ pulse energy(10 W power) and is focussed in vacuum on a moving thin copper tape which generates a bright line source calculated at 10¹³-5*10¹³ photons/sr/s. A custom and optimised multilayer focussing Montel optic delivers between 6*10⁹  and 3*10¹⁰ photons/s (6*10⁶  and 3*10⁷ photons per shot at 1 KHz) on the sample with a 10 mrad convergence and 80 µm FWHM focus Cu-Kα radiation at 1.542Å. Pump-probe time resolved XRD will be possible with UV, visible, near-IR, mid-IR and THz excitation, with an approximate time resolution of 100fs. A Jungfrau 1M area detector will allow 1 KHz frame rate femtosecond time resolved XRD.

https://www.imperial.ac.uk/LUXD/

EPAC

The Extreme Photonics Applications Centre (EPAC) is a new large-scale user facility under construction at the Central Laser Facility (CLF) at STFC Rutherford Appleton Laboratory. Using diode pumped solid-state laser (DPSSL) technology developed at the CLF, the EPAC CPA laser will produce 1 PW peak power, 30 fs pulses at 10 Hz repetition rate. The laser will be focused to ~ 8 x 10¹⁸ Wcm^-2 (a₀ ~ 2) into gas targets to generate multi-GeV electrons through laser wakefield acceleration. The electrons oscillating in the plasma accelerator emit high energy x-rays with a synchrotron-like spectrum, extremely high brightness, micron-scale source size, and ultrashort duration (few fs). Based on previous experiments and simulation, we predict that the beam will contain of order 10¹¹ photons/s/0.1%BW , or 10⁶ photons/s/eV BW, in a few mrad divergence with a critical energy tuneable in the 0.1 – 2.5 Å region. Using this source, EPAC aims to develop an ultrafast x-ray diffraction capability, taking advantage of its brightness for single-shot measurements. We have started to design a beamline incorporating bandwidth limiting and focusing optics, sample stages, and detectors, with a view to first experiments in 2027. Through this workshop, we welcome input from the user community to guide our design, and explore applications that could be supported by this new technology.  

https://www.clf.stfc.ac.uk/Pages/EPAC.aspx

RUEDI

RUEDI is a national facility that has been designed to advance ultrafast science using bright, ultrashort-pulse relativistic electron beams. The facility is based at Daresbury National Laboratory and will consist of two beamlines, diffraction and imaging.For the diffraction beamline, the acceleration voltage will be a few MeV and the minimum pulse widths is aimed to be sub-10 femtosecond. The beamline will consist of an RF gun, a pulse compressor, post-specimen magnifying lens and an electron detector.For applications, both a stroboscopic method and a single shot method will be possible, enabling the elucidation of irreversible processes.The electron pulse width will have two modes: about 10 femtoseconds and several hundred femtoseconds They cover dynamics from the femtosecond to the nanosecond regime. A wide range of sample excitation methods will be available, from ultraviolet to infrared, as well as high-frequency and THz excitation. Sample environments will also be abundant, including gas phase, liquid phase and cryogenic temperatures of mK. The workshop will be jointly organised with related diffraction techniques. They are different in terms of the electron/Xray photon probes, the probe wavelengths and excitation powers. We hope to have constructive discussions from both the user community and the system design community.

https://www.liverpool.ac.uk/relativistic-ultrafast-electron-diffraction-and-imaging/