title: Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates.
abstract: Understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systems and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.
authors.affiliation: Helmholz Zentrum Dresden Rossendorf , Bautzner Landstr. 400, 01328 Dresden, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kovalev
authors.affiliation: Helmholz Zentrum Dresden Rossendorf , Bautzner Landstr. 400, 01328 Dresden, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Green
authors.affiliation: Deutsches Elektronen Synchrotron , Notkestr. 85, 22607 Hamburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Golz
authors.affiliation: Fritz-Haber-Institut der Max Planck Gesellschaft , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Maehrlein
authors.affiliation: Deutsches Elektronen Synchrotron , Notkestr. 85, 22607 Hamburg, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Stojanovic
authors.affiliation: SLAC National Accelerator Laboratory , 2575 Sand Hill Rd, Menlo Park, California 94025, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Fisher
authors.affiliation: Fritz-Haber-Institut der Max Planck Gesellschaft , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kampfrath
authors.affiliation: Helmholz Zentrum Dresden Rossendorf , Bautzner Landstr. 400, 01328 Dresden, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Gensch