Temporal diagnostics from photons: the experience with the PALM

The Photon Arrival and Length Monitor (PALM), a THz streak camera device developed by PSI for non-destructive hard x-ray measurements of photon pulse length and arrival time versus a pump laser[1], was brought to the SACLA XFEL[2] in Japan in a cross-calibration temporal diagnostics campaign after an initial experiment where only the PALM was being used[3]. The device was used with 9 keV pink beam and a 9.0 and 8.8 keV two-color mode, successfully measuring the temporal ifnromation of the pulses for several different FEL operating conditions. The most interesting achievement is the PALM’s ability to measure two arrival times of the two colorors as tey are shifted against each other by the FEL, opening up new possibilities in temporal accuracy for two-color experiments. SwissFEL will employ two such devices at the end stations for use by both operators and experimenters to improve the operation of the FEL and to better interpret experimental data. References [1]P. N. Juranic et. al, Journal of Instrumentation (2014) 9. [2]T. Ishikawa et. al., Nature Photonics (2012) 6(8). [3] P. N. Juranic et. al., Optics Express (2014) 22.