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Wendt, M.

Paper Title Page
PS02 Chromaticity Measurements at HERA-P Using the Head-Tail Technique with Chirp Excitation 103
 
  • M. Wendt, F. Willeke
    DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
  • A. Boudsko
    TRIUMF, Vancouver, Canada
  • O.R. Jones, H. Schmickler
    CERN, Geneva, Switzerland
  
  Experiments have been performed in the HERA proton ring (HERA-p) to test a quasi non-destructive method of chromaticity measurements for protons. The method is based on the detection of the head-tail phase shift of coherend betatron oscillations using a broadband beam position pickup and a commercial “fast-frame” oscilloscope. Previous experiments have relied on a single kick for transverse excitation, whereas the results presented here were carried out using swept frequency “chirp” excitation. The tests proved to be successful, and the method seems to be a good candidate for chromaticity measurement in new large hadron accelerators, such as LHC.  
PT11 Dipole modes study by means of HOM couplers at SBTF 183
 
  • N. Baboi, M. Dohlus, A. Jöstingmeier, N. Holtkamp, M. Wendt, M. Nagl, J. Boster, H. Hartwig
    DESY, Deutsches Elektronen Synchrotron, Hamburg, Germany
  
  High order modes (HOM) are generated by the interaction of a bunched beam with an accelerator environment. They may act destructively on following particle bunches, leading to an increase of the transverse oscillation amplitude and finally to the deterioration of the emittance. Dipole modes have been studied at the S-Band Test Facility at DESY. One accelerating structure, specially designed for this test linac, is equipped with waveguide pick-ups for measuring the HOMs. For one part of the experiments, a modulation of the transverse offset of the bunches at the structure entrance has been induced using a fast broadband kicker and the effect was measured with a precise stripline BPM. No high impedance modes were clearly found in the structure, which has been detuned and damped by both the tapered geometry of the structure and an absorbing stainless steel coating applied on the iris tips.