Author: Grosso, D. R.
Paper Title Page
TUPS009 SEY of Al Samples from the Dipole Chamber of PETRA III at DESY 1533
 
  • D. R. Grosso, R. Cimino, M. Commisso
    INFN/LNF, Frascati (Roma), Italy
  • R. Flammini
    CNR-IMIP, Monterotondo Stazione RM, Italy
  • R. Larciprete
    ISM-CNR, Rome, Italy
  • R. Wanzenberg
    DESY, Hamburg, Germany
 
  At the synchrotron radiation facility PETRA III, tune spectra have been measured with some characteristics which are typically observed at other storage rings in connection with electron cloud effects. For some bunch filling patterns, an increase of the vertical emittance has been observed. To estimate such effects with the available e-cloud simulation codes, the detailed knowledge of the SEY (Secondary Electron Yield) of the Al chamber, is required. To the purpose, representative PETRA III Al samples, were studied in detail at the INFN-LNF Surface Science Laboratory. XPS (X-ray photoelectron spectroscopy) and SEY measurements were performed as a function of electron and argon ion conditioning. The SEY of the as received samples shows a maximum value of δmax ≅ 2.8. Electron conditioning at 500 eV kinetic energy, reduces the SEY to values between δmax ≅ 1.8 to 1.4 (depending on the actual sample analyzed). The XPS characterization of the sample surface, after several cycles of argon ion sputtering, shows clearly that the SEY variation is closely related to the oxidation state of the Al sample, reaching a δmax value as low as 1.3 for our cleanest surface.