The next-generation x-ray source LCLS-II-HE will deliver unprecedented capabilities as an 8 GeV superconducting XFEL, covering photon energies from 250 eV to 13 keV at repetition rates up to 1 MHz. In parallel, an integration of the existing copper-based XFEL with the FACET test facility could become a 2 km accelerator producing 30 GeV electron beams at up to 360 Hz. This development would extend XFEL photon energies to the 1–50 keV range, pushing well beyond current state-of-the-art limits.
This workshop will explore the transformative scientific opportunities enabled by these advances. By combining high photon energies—offering deep penetration and access to large regions of reciprocal space—with full beam coherence, extreme brightness, and ultrafast (1-100 fs) single-shot capabilities, entirely new experimental regimes become accessible. These include probing dynamics in industrially relevant materials, resolving buried functional interfaces, and observing processes within realistic devices. Such capabilities open new pathways for studying disordered and complex systems whose structure and evolution remain largely inaccessible with conventional hard x-ray techniques.
