A beam branching method for timing and spectral characterization of hard X-ray free-electron lasers

• Main Authors: Tetsuo Katayama, Shigeki Owada, Tadashi Togashi, Kanade Ogawa, Petri Karvinen, Ismo Vartiainen, Anni Eronen, Christian David, Takahiro Sato, Kyo Nakajima, Yasumasa Joti, Hirokatsu Yumoto, Haruhiko Ohashi, Makina Yabashi
• Format: Article
• Language: English
• Published: AIP Publishing LLC and ACA 2016-05-01
• Series: Structural Dynamics
• Online Access: http://dx.doi.org/10.1063/1.4939655

We report a method for achieving advanced photon diagnostics of x-ray free-electron lasers (XFELs) under a quasi-noninvasive condition by using a beam-splitting scheme. Here, we used a transmission grating to generate multiple branches of x-ray beams. One of the two primary diffracted branches (+1st-order) is utilized for spectral measurement in a dispersive scheme, while the other (−1st-order) is dedicated for arrival timing diagnostics between the XFEL and the optical laser pulses. The transmitted x-ray beam (0th-order) is guided to an experimental station. To confirm the validity of this timing-monitoring scheme, we measured the correlation between the arrival timings of the −1st and 0th branches. The observed error was as small as 7.0 fs in root-mean-square. Our result showed the applicability of the beam branching scheme to advanced photon diagnostics, which will further enhance experimental capabilities of XFEL.