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Geisler, A.

Paper Title Page
RPAT045 Beam Phase Detection for Proton Therapy Accelerators
 
  • B. A. Aminov, M. G. Getta, S. K. Kolesov, N. Pupeter
    CRE, Wuppertal
  • A. Geisler, T. Stephani, J. H. Timmer
    ACCEL, Bergisch Gladbach
 
  The industrial application of proton cyclotrons for medical applications has become one of the important contributions of accelerator physics during the last years. This paper describes an advanced vector demodulating technique used for non-destructive measurements of beam intensity and beam phase over 360°. A computer controlled I/Q-based phase detector with a very large dynamic range of 70 dB permits the monitoring of beam intensity, phase and eventually energy for wide range of beam currents down to –130 dBm. In order to avoid interference from the fundamental cyclotron frequency the phase detection is performed at the second harmonic frequency. A digital low pass filter with adjustable bandwidth and steepness is implemented to improve accuracy. With a sensitivity of the capacitive pickup in the beam line of 30 nV per nA of proton beam current at 250 MeV, accurate phase and intensity measurements can be performed with beam currents down to 3.3 nA.