Author: Leuschner, N.
Paper Title Page
WEPF05 An Electron Beam Detector for the FLASH II Beam Dump 814
  • F. Perlick, J.D. Good, 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 is 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 2 m distance from the screen, and passes through a vacuum window. Two different optical systems will be installed redundantly for beam image transfer: a conventional lens-mirror-system and a system using a radiation-hard optical fibre bundle. A CCD camera, located in one and a half meter distance from the beam line, is used for the optical analysis. An experimental setup, where the terms of installation of the components correspond to the FLASH accelerator, has been built up in a lab to coordinate the interaction of the screen with the components of the optical system. It was shown that the resolution of the lens-mirror-system is about one line pair per millimeter. An experiment is set up to test the impact of radiation on the optical qualities of the fibre optic bundle by installing it onto a “radioactive hot spot” at the bunch compressor in the FLASH accelerator.  
poster icon Poster WEPF05 [1.926 MB]  
WEPF06 A Fast Switching Mirror Unit at FLASH 818
  • F. Perlick, J.D. Good, N. Leuschner, A.S. Ontoso, M. Sachwitz, L.V. Vu
    DESY Zeuthen, Zeuthen, Germany
  • H. Schulte-Schrepping
    DESY, Hamburg, Germany
  The Free Electron Laser (FLASH) at DESY Hamburg is a linac providing unique experimental opportunities to investigate the atomic structure and the properties of materials, nanoparticles, viruses and cells. At the experimental hall, the incoming FEL beam can be deflected towards five test sites by silicon mirrors mounted into vacuum vessels, of which one is operated in permanent switching mode, allowing the simultaneous use of the light at two different test sites. So far, the entire vacuum vessel with the mirror inside is moved into the beam by a linear motor. This results in high translatory inertia and, to compensate the vessel motion, requires vacuum bellows, which have a limited lifetime especially at higher switching frequencies. Therefore, in the recent design the mirror is shifted by piezo motors operated inside the vessel under ultra-high vacuum conditions. However, temperature measurements revealed that during continuous operation the motor reaches up to 90°C only when exposed to air, necessitating long breaks to allow it to cool. Therefore suitable cooling methods are being investigated to guarantee continuous operation of the motor under ultra-high vacuum conditions.  
poster icon Poster WEPF06 [2.431 MB]