Author: Bravin, E.
Paper Title Page
MOEPPB010 Measurement of Satellite Bunches at the LHC 97
  • A. Jeff, M. Andersen, A. Boccardi, S. Bozyigit, E. Bravin, T. Lefèvre, A. Rabiller, F. Roncarolo
    CERN, Geneva, Switzerland
  • A.S. Fisher
    SLAC, Menlo Park, California, USA
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  Funding: Adam Jeff is a DITANET fellow, supported by the EU's Marie Curie actions contract PITN-GA-2008-215080.
The RF gymnastics involved in the delivery of proton and lead ion bunches to the LHC can result in satellite bunches of varying intensity occupying the nominally empty RF buckets. Quantification of these satellites is crucial for bunch-by-bunch luminosity normalization as well as for machine protection. We present an overview of the longitudinal density monitor (LDM) which is the principal instrument for the measurement of satellite bunches in the LHC. The LDM uses single photon counting of synchrotron light. The very high energies reached in the LHC, combined with a dedicated undulator for diagnostics, allow synchrotron light measurements to be made with both protons and heavy ions. The arrival times of photons are collected over a few million turns, with the resulting histogram corrected for the effects of the detector’s deadtime and afterpulsing in order to reconstruct the longitudinal profile of the entire LHC ring. The LDM has achieved a dynamic range in excess of 105 and a time resolution of 90 ps. Example results are presented and the measurements are benchmarked against satellite distributions based on collision data from the LHC experiments.
MOPPD058 LHC Abort Gap Cleaning Studies during Luminosity Operation 496
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
  • W. Bartmann, A. Boccardi, C. Bracco, E. Bravin, B. Goddard, W. Höfle, D. Jacquet, A. Jeff, V. Kain, M. Meddahi, F. Roncarolo, J.A. Uythoven, D. Valuch
    CERN, Geneva, Switzerland
  The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both Abort Gap (AG) and buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation as well. In this paper the results of experimental studies performed in October 2011 are presented.  
MOPPR048 Beam Instrumentation for the HIE-ISOLDE Linac at CERN 891
  • E. Bravin, A.G. Sosa, D. Voulot, F.J.C. Wenander, F. Zocca
    CERN, Geneva, Switzerland
  • M.A. Fraser
    UMAN, Manchester, United Kingdom
  • J.H. Galipienzo
    AVS, Eibar, Gipuzkoa, Spain
  • M. Pasini
    Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven, Belgium
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  In the framework of the High Intensity and Energy (HIE)-ISOLDE project at CERN, a beam instrumentation R&D program is on-going for the superconducting upgrade of the REX-ISOLDE heavy-ion post-accelerator. An overview of the foreseen beam diagnostics system is presented, focusing on the challenging specifications required by the HIE-ISOLDE linac. Due to the low beam intensities, the diagnostic instrumentation will be based on high-sensitivity intercepting devices. The project includes intensity and transverse profile monitors to be implemented in the very narrow longitudinal space that is available for beam diagnostics in the regions between the superconducting cryomodules. A longitudinal profile monitor is foreseen downstream of the linac to measure the beam energy and arrival time distributions and to allow for a fast phase-tuning of the superconducting cavities. A custom-made emittance meter will provide transverse emittance measurements based on a phase space sampling technique. The design status of the different instruments will be presented as well as the results of some experimental tests.  
MOPPR076 Using the BRAN Luminosity Detectors for Beam Emittance Monitoring During LHC Physics Runs 966
  • A. Ratti, H.S. Matis, M. Placidi, W.C. Turner
    LBNL, Berkeley, California, USA
  • E. Bravin
    CERN, Geneva, Switzerland
  • T.E. Lahey
    SLAC, Menlo Park, California, USA
  • E.S.M. McCrory
    Fermilab, Batavia, USA
  • R. Miyamoto
    ESS, Lund, Sweden
  • S.M. White
    BNL, Upton, Long Island, New York, USA
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The BRAN Ionization Chambers installed at the IP1 and IP5 Interaction Points of the LHC provide a relative measurement of the total and bunch-by-bunch luminosities. This information, combined with the logged bunch charges from a fast BCT monitor, offers the possibility of evaluating the Interaction Area in collision for each of the colliding bunch pairs and monitor its time evolution. A Graphic User Interface (GUI) has been implemented to display the interaction area of the proton bunches interacting in IP1 and IP5 during each of the Physics Runs in the attempt of displaying the contribution to the Luminosity time decay originating from possible emittance blow-up when operating the Accelerator close to the beam-beam limit. Early results confirm the ability to characterize the bunch by bunch emittance behavior during the store and study possible differences among bunches in the same fill.
THPPP050 HIE-ISOLDE SC Linac: Operational Aspects and Commissioning Preparation 3853
  • D. Voulot, E. Bravin, M.A. Fraser, B. Goddard, Y. Kadi, D. Lanaia, A.S. Parfenova, M. Pasini, A.G. Sosa, F. Zocca
    CERN, Geneva, Switzerland
  In the framework of the HIE-ISOLDE project, the REX linac will be upgraded in stages to 5.5 MeV/u and 10 MeV/u using superconducting (SC) quarter-wave cavities. The linac lattice is now frozen and the beam dynamics has been checked. The beam properties at the output of the NC linac for the different stages have been measured and are compatible with the SC linac acceptance. The high-energy beam transfer design is being finalised and a study has been launched for a buncher/chopper system allowing 100 ns bunch spacing for time-of-flight measurements. A compact diagnostic box for the inter-cryomodule region is under development and a new Si-detector based monitor for energy and phase measurements has been tested.