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Redaelli, S.

Paper Title Page
MOPAN081 The LHC Collimator Controls Architecture - Design and Beam Tests 344
 
  • S. Redaelli, R. W. Assmann, P. Gander, M. Jonker, M. Lamont, R. Losito, A. Masi, M. Sobczak
    CERN, Geneva
 
  The LHC collimation system will require simultaneous management by the LHC control system of more than 500 jaw positioning mechanisms in order to ensure the required beam cleaning and machine protection performance in all machine phases, from injection at 450~GeV to collision at 7~TeV. Each jaw position is a critical parameter for the machine safety which could cause a beam dump. In this paper, the architecture of the LHC collimator controls is presented. The basic design to face the accurate and real-time control of the LHC collimators and the interfaces to the other components of LHC Software Application and control infrastructures are described. The full controls architecture has been tested off-line in dedicated test benches, and in the real accelerator environment in the CERN SPS during beam tests with a full scale collimator prototype. The results and the lessons learned are presented.  
TUPAN087 Scenarios for Beam Commissioning of the LHC Collimation System 1577
 
  • C. Bracco, R. W. Assmann, C. Bracco, S. Redaelli, G. Robert-Demolaize
    CERN, Geneva
 
  A complex system of collimators has been designed to protect the superconducting LHC magnets against quench and damage from the high intensity proton beams. The considerable number of collimators and the resulting number of degrees of freedom for their set-up requires a well prepared commissioning strategy. Efficiency studies for various implementations of the LHC collimation system have been performed, taking into account the evolution in optics and beam intensity according to the LHC commissioning schedule. This paper explains the present plans for the set-up sequence of collimators and discusses the relevant tolerances induced from the collimation system for the first years of the LHC operation.  
TUPAN088 Beam Scraping for LHC Injection 1580
 
  • H. Burkhardt, G. Arduini, S. Bart Pedersen, C. Fischer, JJ. G. Gras, A. Koschik, D. K. Kramer, S. Redaelli
    CERN, Geneva
 
  Operation of the LHC will require injection of very high intensity beams from the SPS to the LHC. Fast scrapers have been installed and will be used in the SPS to detect and remove any existing halo before beams are extracted, to minimize the probability for quenching of super-conducting magnets at injection in the LHC. We briefly review the functionality of the scraper system and report about measurements that have recently been performed in the SPS on halo scraping and re-population of tails.  
TUPAN100 Performance Reach of the 1613
 
  • G. Robert-Demolaize, R. W. Assmann, C. Bracco, S. Redaelli, Th. Weiler
    CERN, Geneva
 
  State-of-the-art tracking tools have been developed for detailed LHC collimation and beam loss studies. This includes full chromatic treatment of both beam lines and error models. This paper reviews the main results on the performance reach of the multi-stage LHC collimation system that is being installed in the LHC. Limitations on the allowed proton loss rates and the stored intensity can be derived from the comparison of local losses with estimated quench limits for the superconducting magnets. The origins of the cleaning-related performance limitations are presented and possible improvements are discussed.  
TUPAN108 LHC Collimation System Hardware Commissioning 1625
 
  • Th. Weiler, O. Aberle, R. W. Assmann, R. Chamizo, Y. Kadi, J. Lettry, S. Redaelli
    CERN, Geneva
 
  The stored energy and intensity of the LHC beam exceed the damage level of the machine and the quench level of the magnets by far. Therefore a robust and reliable collimation system is required which prevents the quenching of the magnets during regular operation and protects the accelerator components from damage in the event of beam loss. To assure that the installed collimators will protect the machine and permit the required performance of the collider, an appropriate hardware commissioning has to be implemented. In this contribution we describe the procedures for the hardware commissioning of the LHC collimation system. These procedures will establish the required precision and reliability of collimator movements and settings before the start of beam operation.  
TUPAN107 Beam Loss Response Measurements with an LHC Prototype Collimator in the SPS 1622
 
  • Th. Weiler, G. Arduini, R. W. Assmann, C. Bracco, H.-H. Braun, B. Dehning, P. Gander, E. B. Holzer, M. Jonker, R. Losito, A. Masi, L. Ponce, S. Redaelli, G. Robert-Demolaize, M. Sobczak, J. Wenninger
    CERN, Geneva
 
  Beam tests with an LHC prototype collimator were performed at the SPS in autumn 2006. Applying a new collimator control system many new beam measurements were performed. This contribution presents results on collimator-induced beam loss measurements and their applications to beam-based alignment of collimators and measurements of the beam size and position. Interesting features of the recorded beam loss signals are illustrated and possible impacts for LHC operation are discussed. The measured loss distributions around the full SPS ring are analyzed and compared with simulations.  
WEOAC03 Transverse Impedance of LHC Collimators 2003
 
  • E. Metral, G. Arduini, R. W. Assmann, A. Boccardi, T. Bohl, C. Bracco, F. Caspers, M. Gasior, O. R. Jones, K. K. Kasinski, T. Kroyer, S. Redaelli, G. Robert-Demolaize, G. Rumolo, R. J. Steinhagen, Th. Weiler, F. Zimmermann
    CERN, Geneva
  • F. Roncarolo
    UMAN, Manchester
  • B. Salvant
    EPFL, Lausanne
 
  The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams in case of failures, and which will be moved very close to the beam, with full gaps of few millimetres, in order to protect surrounding super-conducting equipments. We present an estimate of the transverse resistive-wall impedance of the LHC collimators, the total impedance in the LHC at injection and top energy, the induced coupled-bunch growth rates and tune shifts, and finally the result of the comparison of the theoretical predictions with measurements performed in 2004 and 2006 on a prototype collimator installed in the SPS.  
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FROAC03 The Commissioning of the LHC Technical Systems 3801
 
  • R. I. Saban, R. Alemany-Fernandez, V. Baggiolini, A. Ballarino, E. Barbero-Soto, B. Bellesia, F. Bordry, D. Bozzini, M. P. Casas Lino, V. Chareyre, S. D. Claudet, G.-J. Coelingh, K. Dahlerup-Petersen, R. Denz, M. Gruwe, V. Kain, G. Kirby, M. Koratzinos, R. J. Lauckner, S. L.N. Le Naour, K. H. Mess, F. Millet, V. Montabonnet, D. Nisbet, B. Perea-Solano, M. Pojer, R. Principe, S. Redaelli, A. Rijllart, F. Rodriguez-Mateos, R. Schmidt, L. Serio, A. P. Siemko, M. Solfaroli Camillocci, H. Thiesen, W. Venturini Delsolaro, A. Vergara-Fernandez, A. P. Verweij, M. Zerlauth
    CERN, Geneva
  • SF. Feher, R. H. Flora, R. Rabehl
    Fermilab, Batavia, Illinois
 
  The LHC is an accelerator with unprecedented complexity; in addition, the energy stored in magnets and the beams exceeds other accelerators by one to two orders of magnitude. To avoid a plague of technical problems and ensure a safe machine start-up, the hardware commissioning phase was emphasized: the thorough commissioning of technical systems (vacuum, cryogenics, quench protection, power converters, electrical circuits, AC distribution, ventilation, demineralised water, injection system, beam dumping system, beam instrumentation, etc) is carried-out without beam. Activity started in June 2005 with the commissioning of individual systems, followed by operating a full sector of the machine as a whole. LHC architecture allows the commissioning of each of the eight sectors independently from the others, before the installation of other sectors is complete. Important effort went into the definition of the programme and the organization of the coordination in the field, as well as in the tools to record and analyze test results. This paper presents the experience with this approach, results from the commissioning of the first LHC sectors and gives an outlook for future activities.  
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