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Timing Experiments at PETRA IV

Europe/Berlin
DESY Hamburg

DESY Hamburg

Description
Time-resolved experiments at a diffraction limited storage ring
Present-day third-generation synchrotron radiation sources enable a wide range of experiments that exploit the time-structure of the radiation. These include time-of-flight measurements of secondary particles, the study of non-equilibrium phenomena via pump-probe-experiments and nuclear resonant scattering, covering scientific fields that range from the study of gas-phase interactions to the electronic and magnetic properties of correlated materials. All these experiments rely on the short bunch length and the bunch separation in the different operation modi of PETRA III.
In a diffraction-limited storage ring like PETRA IV, the bunch charge will have to be distributed more evenly over the circumference as compared to present-day sources in order to reach a diffraction-limited low emittance.
It is the goal of this workshop to discuss the timing properties that are required for the different fields of applications to make optimum use of PETRA IV. In the ideal case one wishes to compromise as few methods as possible while benefitting as many experiments as possible by combining timing and time-resolution with the outstanding properties of a diffraction limited storage ring.
Invited speakers include:
Ercan Alp (Argonne National Lab)
Christian Bressler (European XFEL GmbH)
Henry Chapman (CFEL - DESY)
Stefan Eisebitt (Max-Born-Institut)
Michael Meyer (European XFEL GmbH)
Michael Rübhausen (U Hamburg)
Tim Salditt (U Göttingen)
Markus Schoeffler (U Frankfurt/M.)
Gerd Schönhense (U Mainz)
Organized by Jens Viefhaus and Ralf Röhlsberger

For organizational issues please contact petra4-workshops-orga@desy.de

    • 13:00 15:30
      Registration and Welcome

      Registration and Welcome for the Workshop on Timing Experiments at PETRA IV

      • 14:00
        Science at PETRA IV: Conditions and Opportunities 30m
        Science at PETRA IV: Conditions and Opportunities
        Speaker: Christian Schroer (DESY Photon Science)
      • 14:30
        Status of the PETRA IV Accelerator Studies 30m
        Status of the PETRA IV Accelerator Studies
        Speaker: Ilya Agapov (DESY Accelerators)
    • 15:30 16:00
      Coffee Break 30m

      Coffee Break

    • 16:00 18:00
      Timing keynote talks

      Timing keynote talks

      • 16:00
        Timing for nuclear resonant scattering 30m
        Timing for nuclear resonant scattering
        Speaker: Ercan Alp (Advanced Photon Source, Argonne National Lab, USA)
      • 16:30
        Pump-probe experiments 30m
        Pump-probe experiments
        Speaker: Christian Bressler (European XFEL)
      • 17:00
        k-Space Microscopy with ToF-Recording and Spin-Filtering – Towards the “Complete” Photoemission Experiment 30m
        Electronic bandstructure, topology of the Fermi surface and the Fermi velocity distribution vF(kF) are key factors in design of materials. They determine the electronic and transport properties and thermodynamics of the electron system and are of high interest for the development of electronic devices. In this talk a novel method (termed k-microscopy) will be presented that has the potential to measure the full electronic structure in a single experiment. This opens the path towards the “complete” photoemission experiment for surfaces and solids, adopting a concept described by Kessler [1] for photoionization of free atoms. k-microscopy is based on high-resolution imaging of the Fourier plane of a cathode lens, with (kx,ky) exceeding the first Brillouin zone. Time-of-flight (ToF) recording of the binding energy EB establishes maximal parallelization. Tunable soft X-rays allow variation of kz via direct transitions to free-electron-like final states. This combination yields 10^8 resolved data points of the 4D spectral density function I(EB,kx,ky,kz) which contains the full information on the electronic structure. First measurements for the prototypical high-Z bcc metal tungsten [2] revealed the full bulk electronic structure, as well as a time-reversal invariant surface state with Dirac-like dispersion and spin texture, measured by an imaging spin filter. For this approach a suitable time structure of the photon pulses is crucial. [1] J. Kessler, Comments Atom. Mol. Phys. 10, 47 (1981) [2] K. Medjanik et al., Nature Materials in print, DOI 10.1038/NMAT4875 (2017)
        Speaker: Prof. Gerd Schoenhense (University of Mainz, Inst fuer Physik)
    • 19:00 21:00
      Dinner at the DESY Bistro 2h

      Dinner at the DESY Bistro

    • 09:00 10:30
      Timing for Nuclear Resonant Scattering

      Timing for Nuclear Resonant Scattering

      Convener: Ercan Alp
      • 09:00
        Fast Shutters for Nuclear Resonant Scattering 30m
        Fast Shutters for Nuclear Resonant Scattering
        Speaker: Tom Toellner (Advanced Photon Source, Argonne National Lab, USA)
      • 09:30
        Non-equilibrium lattice dynamics via NRS 30m
        Non-equilibrium lattice dynamics via NRS
        Speaker: Volker Schünemann (Universität Kaiserslautern)
      • 10:00
        Time-resolved nuclear quantum optics 30m
        Time-resolved nuclear quantum optics
        Speaker: Jörg Evers (Max-Planck Institut für Kernphysik, Heidelberg)
    • 10:30 11:00
      Coffee Break 30m

      Coffee Break

    • 11:00 13:00
      Pump-Probe Experiments

      Pump-Probe Experiments

      Convener: Christian Bressler (European XFEL Facility)
      • 11:00
        tbd 30m
        tbd
        Speaker: Tim Salditt (Universität Göttingen)
      • 11:30
        tbd 30m
        tbd
        Speaker: Stefan Eisebitt (Max-Born Institut, Berlin)
      • 12:00
        tbd 30m
        tbd
        Speaker: Michael Rübhausen (Universität Hamburg)
    • 13:00 14:30
      Lunch 1h 30m

      Lunch break

    • 14:30 15:00
      Pump-Probe Experiments

      Pump-Probe Experiments

      Convener: Christian Bressler (European XFEL Facility)
      • 14:30
        Serial crystallography at a low-emittance storage ring 30m
        Serial crystallography at a low-emittance storage ring
        Speaker: Henry Chapman (DESY CFEL, Hamburg)
    • 15:00 16:00
      Contributed session

      Contributed session

      Conveners: Dr Jens Viefhaus (DESY, FS-PE) , Dr Ralf Roehlsberger Röhlsberger (DESY)
      • 15:00
        Timing experiments at current BSRF and future HEPS 20m
        High Energy Photon Source (HEPS), a near diffraction-limited light source, is planned to be constructed in Beijing in 2018. We will firstly introduce the timing experiment devleopments in current Beijing Synchrotron Radiatino Facility (BSRF), then we will envision the timing experiments in the HEPS with a proposed time-resolved beamline.
        Speaker: Dr Ye Tao (Institute of High Energy Physics)
      • 15:20
        Applied pump-probe X-ray diffraction at synchrotrons 20m
        Synchrotron X-ray sources are among most conventient radiation sources for carrying out time-resolved pump-probe X-ray scattering experiments. Many synchrotron beamlines are currently being equipped with ps and fs lasers to enable laser pump X-ray probe diffraction experiments. At most advanced femtoslicing beamlines the time resolutions below one picosecond is currently achieved. With the progress in X-ray detector technology and the possibility of an electronic detector gating the number of beamlines that offer capability of carrying-out pump-probe experiments is now rapidly increasing. In the talk we will show several examples of pump-probe X-ray diffraction experiments applied to studies of coherent lattice excitations in solids and in surface science applications. We will disclose the technical details of the XPP beamline (BESSY, Berlin) designed for high-repetition rate pump-probe X-ray diffraction experiments. A newly built mobile nanosecond surface X-ray diffraction setup will be described and recent data from the ESRF ID03 beamline demosntrating the proof-of-concept will be presented. Technical questions such as preferred synchrotron bunch structure, laser repetition rate, data acquisition pipeline etc. will be discussed in the context of pump-probe X-ray diffraction.
        Speaker: Dr Roman Shayduk (DESY)
    • 16:00 16:20
      Coffee Break 20m

      Coffee Break

    • 16:20 18:00
      Contributed session

      Contributed session

      Conveners: Dr Jens Viefhaus (DESY, FS-PE) , Dr Ralf Roehlsberger Röhlsberger (DESY)
      • 16:20
        Spatio-temporal coherent control of lattice dynamcis for time-resolved x-ray diffraction 20m
        We employ femtosecond transient grating (TG) spectroscopy to generate and control thermally induced surface deformations. Our sample consists of 60nm Stronthium Titanate on 150 nm Stronthium Ruthenate which is grown on Dysprosium Scandate substrate. We excite the sample with a commercial Titan:Sapphir laser amplifier. The transient grating is generated by imaging a transmission phase mask onto the surface of the sample with the femtosecond laser puls. The optically induced periodic surface distortion, which results from absorption of the excitation laser in Stronthium Ruthenate, allows for in-plane momentum transfer to an incident hard x-ray beam. Thus x-ray photons scatter into high orders of the surface phase grating. We present measurements of the time-dependent dynamics at the surface. The distortion can be decomposed into a thermal background and coherent surface acoustic waves. Based on our data we developped a diffraction model which predicts a peak diffraction efficiency of 33% into the first order of the surface grating. The incoherent thermal background is the main contribution to the surface distortion. By employing a second TG excitation, we perform spatio-temporal cohernt control of diffraction from the surface. We demonstrate enhancment and complete suppression of diffraction from the surface by changing the temporal and spatial overlap between multiple TG excitations. This flexible experimental scheme allows for spanning variable temporal gates for hard x-ray pulses.
        Speaker: Dr Peter Gaal (Institute for Nanostructure and Solid State Physics)
      • 16:40
        Time resolved Scanning X-ray Microcopy of Magnetic Nano Structures 20m
        Pump and Probe dynamic imaging utilizing the stroboscopic nature of synchrotron light as probe is a powerful tool for investigation of magnetization dynamics. To utilize this method we have built, and since 2010 put in user operation, a soft x-ray transmission microscope at an APPLE II undulator beamline at BESSY II. It combines spatial resolutions of up to 15 nm (limited by zone plate optics) and time resolutions down to 40 ps (limited by synchrotron pulse lengths). Sophisticated photon detection and sorting hardware and fast APD point detectors that can operate at 500MHz photon rates not only allow time-resolved measurements using the complete filling pattern of the synchrotron, but also make every synchrotron bucket contribute to each time channel equally and interleaved, yielding shot-noise limited fidelity for dynamic acquisitions. The pump is performed using linear and rotating magnetic fields created by currents through striplines, where synchronization hardware can provide repetition rates from the 400KHz to 30GHz with both RF and patterned excitation shapes. The unique combination of time and spatial resolution and high magnetic sensitivity of XMCD make this method perfectly suited to cover a wide range of magnetic phenomena, as we will present in examples. In particular we will demonstrate results of imaging intense and fast propagating spin-waves (vg > 1 km/sec) with sub 100 nm wavelength, which are expected play a key role for the realization of future magnonic nano devices. Finally we will illustrate how time resolved STXM as a brilliance limited technique can profit from future high brilliance light sources compared to current 3rd generation storage rings.
        Speaker: Dr Markus Weigand (Max Planck Institute for Intelligent Systems)
    • 18:00 19:00
      Session

      Session

      Conveners: Dr Jens Viefhaus (DESY, FS-PE) , Dr Ralf Roehlsberger Röhlsberger (DESY)
    • 19:00 21:00
      Barbecue 2h

      Barbecue Dinner

    • 09:00 10:30
      Time-of-flight methods

      Time-of-flight methods

      Convener: Prof. Gerd Schoenhense (University of Mainz, Inst fuer Physik)
      • 09:00
        tbd 30m
        tbd
        Speaker: Markus Drescher (Universität Hamburg)
      • 09:30
        Atoms & molecules under the reaction microscope 30m
        To investigate the complicated dynamics in atoms and molecules, the measurement of all particles (at least the contributing) ones is favored. With the COLTRIMS reaction microscope technique, we have a complex and powerful tool to measure all charged fragments (electrons and ions) in coincidence. This allows to measure processes of tiny fractions, which are buried underneath 5-6 order of magnitude likelier, competing processes. The technique has developed tremendously and has proven the capability of measuring 5 ions in coincidence (to determine the absolute configuration of a chiral molecule), directly measure high energetic electrons with >500 eV and even in coincidence with a low energetic second electron (<10 eV). We will highlight a few examples and discuss these experiments in the context of our future experimental needs.
        Speaker: Dr Markus Schöffler (Institut für Kernphysik, Goethe-Universität, Frankfurt)
      • 10:00
        tbd 30m
        tbd
        Speaker: Michael Meyer (European XFEL)
    • 10:30 11:00
      Coffee break 30m

      Coffee break

    • 11:00 13:00
      Discussion and Conclusions

      Discussion and Conclusions

      • 11:00
        Reports of the discussion leaders 1h
        Speakers: Christian Bressler (European XFEL Facility) , Ercan Alp, Prof. Gerd Schoenhense (University of Mainz, Inst fuer Physik)
      • 12:00
        Discussion and conclusions 30m
        Speakers: Dr Jens Viefhaus (DESY, FS-PE) , Dr Ralf Roehlsberger Röhlsberger (DESY)
      • 12:30
        Closing remarks 20m
        Speakers: Dr Jens Viefhaus (DESY, FS-PE) , Dr Ralf Roehlsberger Röhlsberger (DESY)