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Roncarolo, F.

Paper Title Page
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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FRPMN092 Beam Coupling Impedance Simulations and Laboratory Measurements for the LHC FP420 Detector 4294
  • F. Roncarolo, R. Appleby, R. M. Jones
    UMAN, Manchester
  The FP420 collaboration* aims at designing forward proton tagging detectors to be installed in the LHC sectors 420 meters downstream of the ATLAS detector and/or CMS detector. The experiment requires modification of the beam pipe material and geometry with a consequent impact on the LHC impedance budget and the circulating beam stability. This paper describes numerical simulations and laboratory measurements carried out to characterize the coupling impedance (longitudinal and transverse) and the associated loss factor of each insertion. The detectors are located in pockets of the beam tube. We study both single and multi-pocket configurations with a view to characterizing the impact on the beam dynamics. In addition, results are compared to available analytical calculations for the resistive wall impedance.

* Cox, Brian et al., "FP420 : An R&D Proposal to Investigate the Feasibility of Installing Proton Tagging Detectors in the 420 m Region of the LHC", CERN-LHCC-2005-025