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heavy-ion

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IT09 Diagnostics in Heavy Ion Machines ion, diagnostics, electron, linac 28
 
  • P. Strehl
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  An overview of the measurements of most important beam parameters in heavy ion machines is given. The special characteristics of heavy ions concerning the great variety of parameters with respect to the type of accelerator (linac, circular machine), the species of accelerated ions as well as their energy, beam intensity, beam emittance and time structure are considered. The consequences for the design of beam diagnostic systems are discussed. Typical examples of measuring systems are given. Experimental results taken during the long operating time of the GSI facilities, covering a wide range of parameters, are reported.  
 
PS05 Recent Improvements of a Cryogenic Current Comparator for nA Ion Beams with High Intensity Dynamics ion, pick-up, instrumentation, linac 109
 
  • A. Peters, H. Reeg, P. Forck
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  • W. Vodel, R. Neubert
    FSU Jena, Institut für Festkörperphysik, Friedrich Schiller Universität, Jena, Germany
  Former measurements of extracted ion beams from the GSI heavy ion synchrotron SIS showed large current fluctuations in the microsecond region with a high peak-to-average ratio. To adapt our Cryogenic Current Comparator (CCC) to this time structure the detector’s electronics have been carefully modified. The most important improvement of the new DC SQUID system affects the enlargement of the bandwidth and the slew rate of the measuring system. In addition the existing data acquisition system for e.g. SEMs (Secondary Emission Monitors) was extended to digitize the CCC signals simultaneously. Measurements of Argon beams will be shown to demonstrate the improved capabilities of the upgraded Cryogenic Current Comparator.  
 
PS12 Performance of the new SPS beam position orbit system (MOPOS) ion, pick-up, proton, extraction 126
 
  • C. Boccard, T. Bogey, J. de Vries, S. Jackson, R. Jones, J.P. Papis, W. Rawnsley, K. Rybaltchenko, H. Schmickler
    CERN, Geneva, Switzerland
  The orbit and trajectory measurement system COPOS of the CERN SPS accelerator has been in operation since the construction of the machine in 1976. Over the years the system has been slightly modified in order to follow the evolving demands of the machine, in particular for its operation as a p-pbar collider and, since 1991, for the acceleration of heavy ions. In 1995 the performance of the system was reviewed and the following shortcomings were identified:
  1. lack of turn-by-turn position measurements due to the 1ms integration time of the voltage to frequency converters used for the analogue to digital conversion (to be compared with a revolution time of 23 ms),
  2. ageing effects on the 200 MHz resonating input filters, which had over the years drifted out of tolerance. As a consequence the signal to noise ratio, the linearity and the absolute precision were affected.
  3. the calibration system based on electromechanical relays had become very unreliable, such that frequent calibrations were no longer possible,
  4. a remote diagnostic for the observation of timing signals relative to the beam signals was missing.
For the above reasons a large-scale upgrade program was launched, the results of which are described in the following sections.