A self-referenced in-situ arrival time monitor for X-ray free-electron lasers

Diez, Michael; Galler, Andreas; Schulz, Sebastian; Boemer, Christina; Coffee, Ryan N.; Hartmann, Nick; Heider, Rupert; Wagner, Martin S.; Helml, Wolfram; Katayama, Tetsuo; Sato, Tokushi; Sato, Takahiro; Yabashi, Makina und Bressler, Christian (2021): A self-referenced in-situ arrival time monitor for X-ray free-electron lasers. In: Scientific Reports, Bd. 11, Nr. 1, 3562

Abstract

We present a novel, highly versatile, and self-referenced arrival time monitor for measuring the femtosecond time delay between a hard X-ray pulse from a free-electron laser and an optical laser pulse, measured directly on the same sample used for pump-probe experiments. Two chirped and picosecond long optical supercontinuum pulses traverse the sample with a mutually fixed time delay of 970 fs, while a femtosecond X-ray pulse arrives at an instant in between both pulses. Behind the sample the supercontinuum pulses are temporally overlapped to yield near-perfect destructive interference in the absence of the X-ray pulse. Stimulation of the sample with an X-ray pulse delivers non-zero contributions at certain optical wavelengths, which serve as a measure of the relative arrival time of the X-ray pulse with an accuracy of better than 25 fs. We find an excellent agreement of our monitor with the existing timing diagnostics at the SACLA XFEL with a Pearson correlation value of 0.98. We demonstrate a high sensitivity to measure X-ray pulses with pulse energies as low as 30 mu J. Using a free-flowing liquid jet as interaction sample ensures the full replacement of the sample volume for each X-ray/optical event, thus enabling its utility even at MHz repetition rate XFEL sources.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 2045-2322
• Sprache: Englisch