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Han, J. H.

Paper Title Page
WEPPH048 XPS Studies of Cs2Te Photocathodes 457
 
  • H. A. Duerr, R. Ovsyannikov, M. Sperling, A. Vollmer
    BESSY GmbH, Berlin
  • J. H. Han, S. Schreiber, S. Lederer
    DESY, Hamburg
  • P. Michelato, L. Monaco, C. Pagani, D. Sertore
    INFN/LASA, Segrate (MI)
  • F. Stephan
    DESY Zeuthen, Zeuthen
 
  Cesium Telluride (Cs2Te) photocathodes are used as sources for electron beams because of their high quantum efficiency (QE) and their ability to release high peak current electron bunches in a high gradient RF-gun. Starting from a high QE level of about 10% the quantum efficiency of these cathodes decreases during operation in a photo-injector to below 0.5%. To understand this behaviour, XPS investigations on the chemical composition were performed at BESSY. In this contribution we compare two fresh cathodes from INFN with one used under normal operation at FLASH and one used at PITZ at a higher than usual RF-gradient of 60 MV/m.  
WEPPH049 Test of a Wiresanner in the Diagnostic Section of PITZ 461
 
  • G. Asova, J. W. Baehr, J. H. Han, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, V. Miltchev, A. Oppelt, B. Petrosyan, M. Sachwitz, L. Staykov, F. Stephan, H.-J. Grabosch
    DESY Zeuthen, Zeuthen
 
  The Photo Injector Test facility at Zeuthen (PITZ) has been established to optimize electron beams of high brilliance needed for short wavelength FELs. In a first step one wire scanner station, developed and used in the undulator section of FLASH at DESY, was tested in the diagnostic section of PITZ. Measurements of the beam-profile and the beam-position were performed to test the useability of such type of wire scanner at PITZ. The obtained results are presented and discussed. The test has shown that wire scanners of this type can be used successfully as complementary measurement device for beam-profile measurements at PITZ. In the final state of extension of PITZ , two wire scanners are foreseen as standard diagnostic tools.