XFELin

XFELin is a conceptual international facility designed to advance X-ray free-electron laser science by delivering ultra-bright, ultrafast X-ray pulses for time-resolved experiments in chemistry, biology, and materials science. The project envisions a linear accelerator that feeds multiple undulator lines, enabling simultaneous experiments and flexible beam delivery. XFELin would provide both hard and soft X-ray beams, with pulse durations ranging from tens of femtoseconds toward the attosecond regime and photon energies spanning roughly 0.3 to 25 keV depending on the beamline. The design emphasizes precise timing synchronization between X-ray pulses and external optical lasers, high repetition rates, and user-friendly instrumentation to support pump–probe and coherent diffractive imaging experiments.

In operation, XFELin would enable time-resolved structural biology, single-particle imaging, catalysis studies, and materials science under extreme conditions. Researchers could observe reaction dynamics in enzymes, track chemical transformations in real time, and study phase transitions in novel materials at atomic length scales. The facility would be complemented by advanced detectors, data analytics, and software for real-time feedback and modeling.

The XFELin concept arose from an international collaboration of universities, national laboratories, and research agencies in the early 2020s, with discussions on site, funding, and governance conducted through feasibility studies. As a proposed facility, it remains subject to design optimization, funding approvals, and construction planning.

Governance would involve a multi-national consortium, with an open-user program, peer-reviewed beam time allocation, and partnerships with industry for instrumentation development. Data management would emphasize open-access principles, with repositories for raw data, metadata, and analysis results.