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Caspers, F.

Paper Title Page
MPPP002 Stochastic Cooling Electrodes for a Wide Velocity Range in the CR 799
 
  • F. Nolden, B.  Franzke, C. Peschke
    GSI, Darmstadt
  • M.C. Balk, R. Schuhmann, T. Weiland
    TEMF, Darmstadt
  • F. Caspers, L. Thorndahl
    CERN, Geneva
 
  The CR storage ring is part of the FAIR project at GSI. It serves as a first stage of stochastic cooling for secondary rare isotopes at v/c=0.83 as well as for antiprotons at v/c=0.97. To avoid the installation of dedicated structures for each kind of beam, electrodes have been developed which are usable for both beams. They are based on slotline structures mounted perpendicular to the beam. They are shorted at the ends, and their signal is extracted by two striplines on the rear side, placed a quarter wavelength away from the open ends. The width of the structures can be adjusted to the initial betatron oscillation amplitudes. Their length is 24 mm, and the signal from many of these structures mounted in a row can be combined. The signal combination can be matched to the different beam velocities. The paper shows results from field calculations, prototype tests, and estimates of the signal combination efficiency. The beam impedance of the novel structures is compared with the superelectrodes applied in the former CERN AC and with the slow-wave structures currently installed in the FNAL Debuncher.  
MPPP031 The CERN-SPS Experiment on Microwave Transmission Through the Beam Pipe 2212
 
  • T. Kroyer, T. Kroyer
    TU Vienna, Vienna
  • F. Caspers, E. Mahner
    CERN, Geneva
 
  Funding: Ministry for Education, Science and Culture, Austria.

In the CERN SPS microwave transmission measurements through beampipe sections with a length of 30 m and 7 m meter respectively have been carried out in the frequency range 2-4 GHz since spring 2003. Here we report on new results obtained with improved measurement techniques during the 2004 run. Observation techniques include a fast real time scope, spectrum analyser IF and video output signal registration and baseband signal observation using a PC soundcard. The unexpected beam induced amplitude modulation has been confirmed on all kinds of available beams including single bunches. It was found that there is a correlation between the amount of beam induced signal attenuation and the beam losses registered by external scintillators. Potential theoretical models are discussed.

 
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.  
TPAP020 Tests of a Roman Pot Prototype for the TOTEM Experiment 1701
 
  • M. Deile, E. Alagoz, G.M. Anelli, G.A. Antchev, M. Ayache, F. Caspers, E. Dimovasili, R. Dinapoli, F.D. Drouhin, K. Eggert, L. Escourrou, O. Fochler, K. Gill, R. Grabit, F. Haug, P. Jarron, J. Kaplon, T. Kroyer, T. Luntama, D. Macina, E. Mattelon, L. Mirabito, H. Niewiadomski, E.P. Noschis, M. Oriunno, A. Park, A.-L. Perrot, O. Pirotte, J.M. Quetsch, F. Regnier, G. Ruggiero, S. Saramad, P. Siegrist, W. Snoeys, T. Souissi, R. Szczygiel, J. Troska, F. Vasey, A. Verdier
    CERN, Geneva
  • V. Avati, M. Järvinen, M. Kalliokoski, J. Kalliopuska, K. Kurvinen, R. Lauhakangas, F. Oljemark, R. Orava, V. Palmieri, H. Saarikko, A. Soininen, K. Österberg
    Helsinki University, Department of Physics, University of Helsinki
  • V. Berardi, M.G. Catanesi, E. Radicioni
    INFN-Bari, Bari
  • V. Boccone, M. Bozzo, A. Buzzo, S. Cuneo, F. Ferro, M. Macri, S. Minutoli, A. Morelli, P. Musico, M. Negri, A. Santroni, G. Sette, A. Sobol
    INFN Genova, Genova
  • C. Da Vià, J. Hasi, A. Kok, S. Watts
    Brunel University, Middlesex
  • J. Kasper, V. Kundrât, M. V. Lokajicek, J. Smotlacha
    FZU, Prague
 
  The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC.* TOTEM Roman Pots contain stacks of 10 silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10 σ + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are used both for precise track reconstruction and for triggering. The first full-sized prototypes of both detector technologies as well as their read-out electronics have been developed, built and operated. The tests took place first in a fixed-target muon beam at CERN's SPS, and then in the proton beam-line of the SPS accelerator ring. We present the test beam results demonstrating the successful functionality of the system despite slight technical shortcomings to be improved in the near future.

TOTEM, Technical Design Report, CERN-LHCC-2004-002.

 
FPAT021 Experience with Kicker Beam Coupling Reduction Techniques 1742
 
  • E.H.R. Gaxiola, J. Bertin, F. Caspers, L. Ducimetière, T. Kroyer
    CERN, Geneva
 
  SPS beam impedance is still one of the worries for operation with nominal LHC beam over longer periods once the final configuration will be installed in 2006. Several CERN SPS kickers suffer from significant beam induced ferrite heating. In specific cases, for instance beam scrubbing, the temperature of certain ferrite yokes went beyond the Curie point. Several retrofit impedance reduction techniques have been investigated theoretically and with practical tests. We report on experience gained during the 2004 SPS operation with restively coated ceramic inserts in terms of kicker heating, pulse rise time, operating voltage, and vacuum behavior. For another technique using interleaved metallic strips we observed significant improvements in bench measurements. Advantages and drawbacks of both methods and potential combinations of them are discussed and simulation as well as measured data are shown. Prospects for further improvements beyond 2006 are briefly outlined.