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Iversen, J.I.

Paper Title Page
MOPCH154 Dry-ice Cleaning on SRF Cavities 418
 
  • A. Brinkmann, J.I. Iversen, D. Reschke, J. Ziegler
    DESY, Hamburg
  
  High pressure rinsing with ultra-pure water is the well-proven standard cleaning step after chemical or electrochemical surface treatment of SRF cavities. Dry-ice cleaning (DIC) is a powerful additional cleaning option which depends on the sublimation-impulse method. Particles and film contaminations, especially hydro-carbons, are removed without residues. Furthermore DIC offers the possibility of a final horizontal cleaning of a fully equipped cavity because water is not present in the cleaning process. Horizontal cleaning tests on single-cell cavities showed promising high gradient, high Q-value performances, but field emission is still the limiting effect. On the basis of these tests a new IR-heater module is installed to keep a high temperature gradient between the CO2 jet and the cavity surface. New test results for this optimized cleaning set-up will be presented.  
THPLS092 Nb-Pb Superconducting RF-Gun 3493
 
  • J.S. Sekutowicz, J.I. Iversen, D. Klinke, D. Kostin, W.-D. Möller
    DESY, Hamburg
  • I. Ben-Zvi, A. Burrill, T. Rao, J. Smedley
    BNL, Upton, Long Island, New York
  • M. Ferrario
    INFN/LNF, Frascati (Roma)
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • K. Ko, L. Xiao
    SLAC, Menlo Park, California
  • J. Langner, P. Strzyzewski
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  • R.S. Lefferts, A.R. Lipski
    SBUNSL, Stony Brook, New York
  • J.B. Rosenzweig
    UCLA, Los Angeles, California
  • K. Szalowski
    University of Lodz, Lodz
  
  We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper.