Conclusions from the UK XFEL conceptual design and options analysis study

UK XFEL is a multi-stage project to pursue ‘next-generation’ XFEL capabilities, either through developing a new facility in the UK or by investing at existing machines. The project’s Science Case envisages a step-change increase in the number of simultaneous experiments, with transform-limited (‘laser-like’) x-rays across a wide range of pulse durations and photon energies (up to ~20 keV) being delivered together with an array of synchronised sources, at high repetition rate to approximately ten FELs (evenly spaced pulses at approximately 100 kHz per experiment, with flexibility). A subset of applications require increased pulse energy and higher photon energies at low repetition rate or in short bursts. The project is now in the final year of its three-year conceptual design and options analysis phase, in which it has produced a conceptual design to efficiently meet these requirements, as well as conducting an analysis of the costs, socio-economic factors, and sustainability of the different investment options. The conclusions of this study are expected to be of general interest to the community.