title: A multi-MHz single-shot data acquisition scheme with high dynamic range: pump-probe X-ray experiments at synchrotrons.
abstract: The technical implementation of a multi-MHz data acquisition scheme for laser-X-ray pump-probe experiments with pulse limited temporal resolution (100 ps) is presented. Such techniques are very attractive to benefit from the high-repetition rates of X-ray pulses delivered from advanced synchrotron radiation sources. Exploiting a synchronized 3.9 MHz laser excitation source, experiments in 60-bunch mode (7.8 MHz) at beamline P01 of the PETRA III storage ring are performed. Hereby molecular systems in liquid solutions are excited by the pulsed laser source and the total X-ray fluorescence yield (TFY) from the sample is recorded using silicon avalanche photodiode detectors (APDs). The subsequent digitizer card samples the APD signal traces in 0.5 ns steps with 12-bit resolution. These traces are then processed to deliver an integrated value for each recorded single X-ray pulse intensity and sorted into bins according to whether the laser excited the sample or not. For each subgroup the recorded single-shot values are averaged over ∼107pulses to deliver a mean TFY value with its standard error for each data point, e.g. at a given X-ray probe energy. The sensitivity reaches down to the shot-noise limit, and signal-to-noise ratios approaching 1000 are achievable in only a few seconds collection time per data point. The dynamic range covers 100 photons pulse-1and is only technically limited by the utilized APD.
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Alexander
authors: A
authors: Britz
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Tadesse A
authors: TA
authors: Assefa
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Andreas
authors: A
authors: Galler
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Wojciech
authors: W
authors: Gawelda
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Michael
authors: M
authors: Diez
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Peter
authors: P
authors: Zalden
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Dmitry
authors: D
authors: Khakhulin
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Bruno
authors: B
authors: Fernandes
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Patrick
authors: P
authors: Gessler
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Hamed
authors: H
authors: Sotoudi Namin
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Andreas
authors: A
authors: Beckmann
authors: Deutsches Elektronen-Synchrotron (PETRA III), Notkestraße 85, 22607 Hamburg, Germany.
authors: Manuel
authors: M
authors: Harder
authors: Deutsches Elektronen-Synchrotron (PETRA III), Notkestraße 85, 22607 Hamburg, Germany.
authors: Hasan
authors: H
authors: Yavaş
authors: European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
authors: Christian
authors: C
authors: Bressler
keywords: data acquisition instrumentation; multi-photon counting; time-resolved X-ray absorption spectroscopy; ultrafast detection