Author: Grünert, J.
Paper Title Page
K-Monochromator for Undulator Commissioning at the European XFEL  
  • W. Freund, J. Grünert, A. Koch
    XFEL. EU, Hamburg, Germany
  Photon beam based commissioning of the European XFEL undulators requires variable 4-bounce monochromator systems equipped with Si(111) channel-cut crystals. With two different methods we will measure the K-parameters of each segment of the SASE undulators (e.g. SASE1 has 35 segments) which has to be tuned to a precision of better than 2·10-4 in order to achieve lasing conditions. Precise magnetic K-tuning of the undulator segments is performed in the magnetic lab, but this measurement is not available after undulator installation in the tunnel. We will describe the K-monochromator system for the first undulator beamline SASE1, which is planned to be installed this year. The system consists of three main components, a chamber with filter foils, a monochromator chamber with two goniometers carrying the channel-cut crystals, and a detection chamber with an imager and a photodiode. For the imaging system we will use a highly sensitive sCMOS camera with tandem lens optics for high numerical aperture and up to three different scintillation screens.  
MOP012 Implementation Phase of the European XFEL Photon Diagnostics 41
  • J. Grünert, J. Buck, F. Dietrich, W. Freund, A. Koch, M. Planas
    XFEL. EU, Hamburg, Germany
  The European XFEL facility with 3 undulators and initially 6 experimental end-stations requires an extensive set of photon beam diagnostics for commissioning and user operation, capable of handling the extreme brilliance and its inherent damage potential, and the high intra bunch train repetition rate of 4.5MHz, potentially causing additional damage by high heat loads and making shot-to-shot diagnostics very demanding [1]. After extensive design [2-4] and prototype studies, in 2014 the installation of the photon beam devices starts with the equipment in the first photon tunnel XTD2 which is where the SASE1 hard X-ray undulator is located. This contribution reports on the device construction progress by focusing on the XTD2 tunnel devices and their implementation into the tunnel environment. [1] J.Grünert, Framework for X-Ray Photon Diagnostics at the European XFEL, TR-2012-003, 04/2012 [2] J.Buck, Online Photoemission Time-of-Flight Spectrometer for X-ray Photon Diagnostics, TR-2012-002, 06/2012 [3] C.Ozkan, Conceptual design report for Imaging Stations at the European XFEL, TR-2012-004, 02/2012 [4] W.Freund, The European XFEL Undulator Commissioning Spectrometer, XFEL. EU 05/2011  
Design of Invasive X-ray Beam Diagnostic Devices for the European XFEL Employing Scintillators for Imaging  
  • A. Koch, W. Freund, J. Grünert
    XFEL. EU, Hamburg, Germany
  The European XFEL facility requires diagnostics of its x-ray photon beam. Imaging stations will be employed for invasive characterisations of beam properties like position, profile, and pointing. In combination with monochromators or dispersive devices, imagers can also deliver spectral information. This contribution will describe the design of different imaging stations, their expected performance and first characterisations, especially in terms of signal-to-noise properties, spatial resolution and radiation hardness. The challenge in the design is to deal with a wide range of beam properties: photon energies from 0.26 – 36 keV, beam sizes from several 100 um to mm, pulse durations of 10 fs and pulse energies up to 10 mJ which may destroy materials by single pulses. The main components of these imaging stations are: scintillators for conversion of x-rays to visible light, mirrors - both in vacuum - specialised optics and CCD / CMOS cameras for image recording.  
MOP014 X-ray Photon Temporal Diagnostics for the European XFEL 45
  • J. Liu, J. Buck, F. Dietrich, W. Freund, J. Grünert, M. Meyer
    XFEL. EU, Hamburg, Germany
  European XFEL (XFEL. EU) that will commissioning in 2016 shows great features on its extremely high number of light bullets (27000 p/s) and extremely high average brilliance. The FEL pulses in XFEL. EU are produced in a 10 Hz bunch trains that contains 2700 sub-pulses within the 600 μs time intervals, corresponding to a 220 ns sub-pulse separation and 4.5 MHz repetition rate. Characterizing the temporal properties of the high repetition rate FEL pulses that implicitly different from shot to shot is important for “pump and probe” experiments and data interpretation. Here we report the concept and recent progress about temporal diagnostic for XFEL. EU. THz streaking technique and spectral encoding will be implemented considering the high repetition rate and high brilliance of XFEL. EU. Laser based THz generation, optimization and numerical simulation for streaking FEL electrons with different photon energies will be presented. High repetition rate diagnostic requirements and solutions will also be discussed.