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Bohl, T.

Paper Title Page
MPPP033 Beam Transfer Functions and Beam Stabilisation in a Double RF System 2300
 
  • E.N. Shaposhnikova, T. Bohl, T.P.R. Linnecar
    CERN, Geneva
 
  The high intensity proton beam for LHC accelerated in the CERN SPS is stabilised against coupled-bunch instabilities by a 4th harmonic RF system in bunch-shortening mode. Bunch-lengthening mode, which could also be useful to reduce peak line density and alleviate problems from e-cloud and kicker heating does not give desirable results for beam stability. In this paper an analysis of the limitations of these two different modes of operation is presented together with measurements of the Beam Transfer Function for the double RF system. As predicted by theory, for sufficiently long bunches with the same noise excitation, the measured amplitude of the beam response in bunch-lengthening mode is an order of magnitude higher than that for bunch-shortening mode or for a single RF system.  
TPAP016 Energy Calibration of the SPS with Proton and Lead Ion Beams 1470
 
  • J. Wenninger, G. Arduini, C. Arimatea, T. Bohl, P. Collier, K. Cornelis
    CERN, Geneva
 
  The momentum of the 450 GeV/c proton beam of the CERN Super Proton Synchrotron was determined by a high precision measurement of the revolution frequencies of proton and lead ion beams. To minimize systematic errors the magnetic cycle of the SPS had to be rigorously identical for both beams, and corrections due to Earth tides had to be taken into account. This paper presents how the beam momentum was determined from the RF frequency for which the beams are centred in the machine sextupoles. The measured beam momentum is 449.16 ± 0.14 GeV/c for a nominal momentum of 450 GeV/c, and the accuracy is limited by systematic errors.  
ROPC004 Recent Intensity Increase in the CERN Accelerator Chain 413
 
  • E.N. Shaposhnikova, G. Arduini, T. Bohl, M. Chanel, R. Garoby, S. Hancock, K. Hanke, T.P.R. Linnecar, E. Métral, R.R. Steerenberg, B. Vandorpe
    CERN, Geneva
 
  Future requests for protons from the physics community at CERN, especially after the start-up of the CNGS experiments in 2006, can only be satisfied by a substantial increase in the SPS beam intensity per pulse. In September 2004 a three weeks beam run was dedicated to high intensity; all accelerators in the chain were pushed to their limits to study intensity restrictions and find possible solutions. New record intensities were obtained in the accelerators of the PS & SPS Complex with this fixed-target type beam which is different from the nominal LHC beam. The challenges in producing this high-intensity beam are described together with the measures needed to make it fully operational.