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Bohl, T.

Paper Title Page
MOPC131 Ions for LHC: Towards Completion of the Injector Chain 376
 
  • D. Manglunki, M. Albert, M.-E. Angoletta, G. Arduini, P. Baudrenghien, G. Bellodi, P. Belochitskii, E. Benedetto, T. Bohl, C. Carli, E. Carlier, M. Chanel, H. Damerau, S. S. Gilardoni, S. Hancock, D. Jacquet, J. M. Jowett, V. Kain, D. Kuchler, M. Martini, S. Maury, E. Métral, L. Normann, G. Papotti, S. Pasinelli, M. Schokker, R. Scrivens, G. Tranquille, J. L. Vallet, B. Vandorpe, U. Wehrle, J. Wenninger
    CERN, Geneva
 
  The CERN LHC experimental programme includes heavy ion physics with collisions between two counter-rotating Pb82+ ion beams at a momentum of 2.76 TeV/c/nucleon per beam and luminosities as high as 1·1027 cm-2 s-1. To achieve the beam parameters required for this operation the ion accelerator chain has undergone substantial modifications. Commissioning with beam of the various elements of this chain started in 2005 and in 2007 it was the turn of the final stage, the Super-Proton-Synchrotron (SPS) following extensive changes to the low-level RF hardware. The major limitations of this mode of operation of the SPS (space charge, intra-beam scattering) are presented, together with the performance reached so far. The status of the pre-injector performance will also be reviewed together with a description of the steps required to reach nominal performance.  
TUPC098 Results of the LHC Prototype Chromaticity Measurement System Studies in the CERN-SPS 1290
 
  • R. J. Steinhagen, A. Boccardi, T. Bohl, M. Gasior, O. R. Jones, J. Wenninger
    CERN, Geneva
  • K. K. Kasinski
    AGH, Cracow
 
  Tune and chromaticity control is an integral part of safe and reliable LHC operation. Tight tolerances on the maximum transverse beam excursions allow oscillation amplitudes of less than 30 um. This leaves only a small margin for transverse beam and momentum excitations required for measuring tune and chromaticity. This contribution discusses the baseline LHC continuous chromaticity measurement with results from tests at the CERN-SPS. The system is based on continuous tracking of the tune using a phase-locked-loop (PLL) while modulating the beam momentum. The high PLL tune resolution achieved ( ~1·10-6 ) made it possible to detect chromaticity changes well below the nominally required 1 unit for relative momentum modulations of only 2·10-5. The sensitive tune measurement front-end employed allowed the PLL excitation and radial amplitudes to be kept below a few tens of micrometers. These results show that this type of measurement can be considered as practically non-perturbative permitting its use even during nominal LHC operation.  
TUPP059 Study of Controlled Longitudinal Emittance Blow-up for High Intensity LHC Beams in the CERN SPS 1676
 
  • G. Papotti, T. Bohl, T. P.R. Linnecar, E. N. Shaposhnikova, J. Tuckmantel
    CERN, Geneva
 
  Preventive longitudinal emittance blow-up, in addition to a fourth harmonic Landau damping RF system, is required to keep the LHC beam in the SPS stable up to extraction. The beam is blown-up in a controlled way during the acceleration ramp by using band-limited phase noise targeted to act inside the synchrotron frequency spread, which is itself modified both by the second RF system and by intensity effects (beam loading and others). For a high intensity beam these latter effects can lead to a non-uniform emittance blow-up and even loss of stability for certain bunches in the batch. In this paper we present studies of the emittance blow-up achieved with high intensity beams under different conditions of both RF and noise parameters.  
TUPP066 CERN SPS Impedance in 2007 1691
 
  • E. Métral, G. Arduini, T. Bohl, H. Burkhardt, F. Caspers, H. Damerau, T. Kroyer, H. Medina, G. Rumolo, M. Schokker, E. N. Shaposhnikova, J. Tuckmantel
    CERN, Geneva
  • R. Calaga
    BNL, Upton, Long Island, New York
  • B. Salvant
    EPFL, Lausanne
  • B. Spataro
    INFN/LNF, Frascati (Roma)
 
  Each year several measurements of the beam coupling impedance are performed in both longitudinal and transverse planes of the CERN Super Proton Synchrotron to keep track of its evolution. In parallel, after the extensive and successful campaign of identification, classification and cure of the possible sources of (mainly longitudinal) impedance between 1998 and 2001, a new campaign (essentially for the transverse impedance this time) has started few years ago, in view of the operation of the SPS with higher intensity for the LHC luminosity upgrade. The present paper summarizes the results obtained from the measurements performed over the last few years and compares them to our predictions. In particular, it reveals that the longitudinal impedance is reasonably well understood and the main contributors have already been identified. However, the situation is quite different in the transverse plane: albeit the relative evolution of the transverse impedance over the last few years can be well explained by the introduction of the nine MKE kickers necessary for beam extraction towards the LHC, significant contributors to the SPS transverse impedance have not been identified yet.