Electro-optic time profile monitors for femtosecond electron bunches at the soft x-ray free-electron laser FLASH

B. Steffen, V. Arsov, G. Berden, W. A. Gillespie, S. P. Jamison, A. M. MacLeod, A. F. G. van der Meer, P. J. Phillips, H. Schlarb, B. Schmidt, P. Schmüser

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    Precise measurements of the temporal profile of ultrashort electron bunches are of high interest for the optimization and operation of ultraviolet and x-ray free-electron lasers. The electro-optic (EO) technique has been applied for a single-shot direct visualization of the time profile of individual electron bunches at FLASH. This paper presents a thorough description of the experimental setup and the results. An absolute calibration of the EO technique has been performed utilizing simultaneous measurements with a transverse-deflecting radio-frequency structure that transforms the longitudinal bunch charge distribution into a transverse streak. EO signals as short as 60 fs (rms) have been observed using a gallium-phosphide (GaP) crystal, which is a new record in the EO detection of single electron bunches and close to the physical limit imposed by the EO material properties. The data are in quantitative agreement with a numerical simulation of the EO detection process.

    Original languageEnglish
    Article number032802
    Pages (from-to)-
    Number of pages16
    JournalPhysical Review Special Topics - Accelerators and Beams
    Issue number3
    Publication statusPublished - Mar 2009



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