Author: Leuschner, N.
Paper Title Page
Synchrotron Radiation Monitor for Beam Energy Measurements at the European XFEL  
  • M. Sachwitz, N. Leuschner, F. Perlick
    DESY Zeuthen, Zeuthen, Germany
  • C. Gerth, H. Huegelmann
    DESY, Hamburg, Germany
  Monitoring of the electron beam energies after the various accelerating sections of the European XFEL is essential for an optimal beam delivery system. Synchrotron radiation that is emitted in the dispersive section of the magnetic chicanes employed for longitudinal bunch compression can be used to determine the energy spectrum of the electron bunches. At European XFEL, vacuum chambers with an aperture of 400 mm will be installed for flexible operation of different bunch compression scenarios. Therefore, the in-vacuum mirror deflecting the visible light through a vacuum window to a camera is located on a motor driven carrier. An additional mover allows an angular adjustment of the mirror. In this paper we report on the conceptual design of the synchrotron monitor. Results obtained with a prototype setup in the laboratory are presented and several options for the synchrotron light detection are discussed.  
Installation and First Measurements of an Electron Beam Detector at the FLASH II Beam Dump  
  • F. Perlick, N. Leuschner, M. Sachwitz
    DESY Zeuthen, Zeuthen, Germany
  • G. Kube, M. Schmitz, K. Wittenburg, T. Wohlenberg
    DESY, Hamburg, Germany
  For the electron absorber at FLASH II a detector has been developed to control the position, dimensions and profile of the electron beam. Scintillation light, emitted from a luminescent screen in front of the dump window, is reflected by a mirror, located in two meter distance from the screen, and passes through a vacuum window. For optical analysis, the beam image is then transferred by an optical fibre bundle to a CCD camera, which is located in one meter distance from the beam line. To test the survivability of the fibre bundle in such a highly radioactive environment, an irradiation test was performed by installing a similar fibre bundle onto a radioactive hot spot at FLASH. The test revealed that the fibre’s optical qualities after irradiation of approximately one megagray degraded by less than ten percent. After the optical system had been simulated in an experimental setup in the lab, showing satisfactory results, the monitor has recently been installed and adjusted at FLASH II. The results of the first measurements will be presented in the paper.