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Burkhardt, H.

Paper Title Page
MPPE011 Expected Emittance Growth and Beam Tail Repopulation from Errors at Injection into the LHC 1266
 
  • B. Goddard, H. Burkhardt, V. Kain, T. Risselada
    CERN, Geneva
 
  The preservation of the transverse emittance of the proton beam at injection into the LHC is crucial for luminosity performance. The population of the beam tails is also important for beam losses and collimation. The transfer and injection process is particularly critical in this respect, and several effects can contribute to the expected emittance increase and tail repopulation, like optical and geometrical mismatch, injection offsets and coupling, etc. The various effects are described, together with the tolerance limits on the parameters, and the expected contributions evaluated analytically where possible. The emittance growth and tail distributions are also simulated numerically using realistic errors. The implications for the tolerances on the matching of the transfer lines are discussed.  
MPPE047 Optics Flexibility and Matching at LHC Injection 2983
 
  • H. Burkhardt, O.S. Brüning, B. Goddard, V. Kain, V. Mertens, T. Risselada, A. Verdier
    CERN, Geneva
 
  An excellent match between the SPS, the several kilometers long transfer lines and the LHC will be required to minimise emittance blow-up at injection. Several optics changes in the SPS and the LHC injection insertions had to be accommodated in the design phase. The new 3-phase collimation system in the transfer lines results in additional phase advance constraints. It will be important to maintain some tuning range for the LHC commissioning phase and to accommodate possible further optics changes. We analyse the requirements, the constraints, the current status and options to enhance the optics flexibility.  
MPPE048 Beam Based Alignment of the LHC Transfer Line Collimators 3034
 
  • V. Kain, H. Burkhardt, B. Goddard, S. Redaelli
    CERN, Geneva
 
  At LHC injection energy the aperture available in the transfer lines and in the LHC is small and the intensities of the injected beams are an order of magnitude above the damage level. The setting of protection elements such as the transfer line collimators is therefore very critical; mechanical and optical tolerances must be taken into account to define the nominal setting. Being able to measure and control the collinearity of the collimator jaws with the beam relaxes the requirement on the settings considerably. A method to measure angular misalignment of the collimator jaws in the transfer line based on a transmission measurement is discussed. Simulations have been made and are compared with the results of an alignment test performed with beam during the 2004 commissioning of the transfer line TI 8.  
TPAP007 LHC Collimation: Design and Results from Prototyping and Beam Tests 1078
 
  • R.W. Assmann, O. Aberle, G. Arduini, A. Bertarelli, H.-H. Braun, M. Brugger, H. Burkhardt, S. Calatroni, F. Caspers, E. Chiaveri, A. Dallocchio, B. Dehning, A. Ferrari, M. Gasior, A. Grudiev, E.B. Holzer, J.-B. Jeanneret, J.M. Jimenez, Y. Kadi, R. Losito, M. Magistris, A.M. Masi, M. Mayer, E. Métral, R. Perret, C. Rathjen, S. Redaelli, G. Robert-Demolaize, S. Roesler, M. Santana-Leitner, D. Schulte, P. Sievers, E. Tsoulou, H. Vincke, V. Vlachoudis, J. Wenninger
    CERN, Geneva
  • I. Baishev, I.L. Kurochkin
    IHEP Protvino, Protvino, Moscow Region
  • G. Spiezia
    Naples University Federico II, Science and Technology Pole, Napoli
 
  The problem of collimation and beam cleaning concerns one of the most challenging aspects of the LHC project. A collimation system must be designed, built, installed and commissioned with parameters that extend the present state-of-the-art by 2-3 orders of magnitude. Problems include robustness, cleaning efficiency, impedance and operational aspects. A strong design effort has been performed at CERN over the last two years. The system design has now been finalized for the two cleaning insertions. The adopted phased approach is described and the expected collimation performance is discussed. In parallel robust and precisely controllable collimators have been designed. Several LHC prototype collimators have been built and tested with the highest beam intensities that are presently available at CERN. The successful beam tests are presented, including beam-based setup procedures, a 2 MJ robustness test and measurements of the collimator-induced impedance. Finally, an outlook is presented on the challenges that are ahead in the coming years.  
TPAP008 Measurements of the LHC Collimator Impedance with Beam in the SPS 1132
 
  • H. Burkhardt, G. Arduini, R.W. Assmann, F. Caspers, M. Gasior, A. Grudiev, O.R. Jones, T. Kroyer, E. Métral, S. Redaelli, G. Robert-Demolaize, F. Roncarolo, D. Schulte, R.J. Steinhagen, J. Wenninger, F. Zimmermann
    CERN, Geneva
 
  The transverse impedance of the LHC collimators will likely dominate the overall transverse impedance in the LHC at high energies and potentially limit the maximum intensity. A prototype collimator was recently tested in the SPS. Small, but significant tune shifts depending on the collimator position have been observed using different independent high resolution tune measurement methods. In addition trapped modes predicted from numerical simulation at the ends of the collimator jaws have been identified by bench measurement techniques as well as with the beam. We present a description of the measurements and an analysis of the results.  
TPAP009 Collimation in the Transfer Lines to the LHC 1135
 
  • H. Burkhardt, B. Goddard, Y. Kadi, V. Kain, T. Risselada, W.J.M. Weterings
    CERN, Geneva
 
  Injection intensities for the LHC are over an order of magnitude above damage level. The TI 2 and TI 8 transfer lines between the SPS and LHC are each about 2.5 km long and comprise many active elements running in pulsed mode. The collimation system in the transfer lines is designed to dilute the beam energy sufficiently in case of accidental beam loss or mis-steered beam. A system using three collimator families spaced by 60 degrees in phase advance, both in the horizontal and the vertical plane has been chosen. We discuss the reasons for this choice, the layout and, the expected performance of the system in terms of maximum amplitudes and energy deposition.