High-brightness self-seeded X-ray free-electron laser covering the 3.5 keV to 14.6 keV range

A self-seeded X-ray free-electron laser (XFEL) is a promising approach to realize bright, fully coherent (FEL) sources in the hard domain that have been long-standing issue with longitudinal coherence remaining challenging. At Pohang Accelerator Laboratory XFEL, we demonstrated XFEL peak brightness of 3.2 × 1035 photons s–1 mm–2 mrad–2 0.1% bandwidth (BW)–1 at 9.7 keV. The (0.19 eV) about 1/70 times as wide (close Fourier transform limit) and spectral 40 higher than self-amplified spontaneous emission (SASE), substantial improvements stability self-seeding noticeably suppressed pedestal effects. We could reach an excellent performance photon energy 3.5 keV (lowest) 14.6 (highest) same self-seeding. seeded FEL was 0.32 eV, 1.3 0.1%BW–1. show use pulses reproducibility cleaner spectrum results serial femtosecond crystallography data superior quality compared collected using SASE mode. provides 0.1%BW–1 very small shot-to-shot electron jitter 0.012%.