Author: Kain, V.
Paper Title Page
MOPFI050 Non-local Fast Extraction from the CERN SPS at 100 and 440 GeV 392
 
  • F.M. Velotti, A. Alekou, W. Bartmann, E. Carlier, K. Cornelis, I. Efthymiopoulos, B. Goddard, L.K. Jensen, V. Kain, M. Kowalska, V. Mertens, R. Steerenberg
    CERN, Geneva, Switzerland
 
  The Long Straight Section 2 (LSS2) of the CERN SPS is connected with the North Area (NA), to which the beam to date has always been extracted using a resonant extraction technique. For new proposed short- and long-baseline neutrino experiments, a fast single turn extraction to this experimental area is required. As there are no kickers in LSS2, and the integration of any new kickers with the existing electrostatic septum would be problematic, a solution has been developed to fast extract the beam using non-local extraction with other SPS kickers. Two different kicker systems have been used, the injection kicker in LSS1 and the stronger extraction kicker in LSS6 to extract 100 and 440 GeV beam, respectively. For both solutions a large emittance beam was extracted after 5 or 9 full betatron periods. The concept and simulation details are presented with the analysis of the aperture and beam loss considerations and experimental results collected during a series of beam tests.  
 
MOPFI053 Upgrades of the SPS, Transfer Line and LHC Injection Protection Devices for the HL-LHC Era 401
 
  • Ö. Mete, O. Aberle, F. Cerutti, K. Cornelis, B. Goddard, V. Kain, R. Losito, F.L. Maciariello, M. Meddahi, A. Mereghetti, J.A. Uythoven, F.M. Velotti
    CERN, Geneva, Switzerland
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
 
  The challenging High Luminosity LHC (HL-LHC) beam requirements will lead in the future to unprecedented beam parameters along the LHC injector chain. In the SPS accelerator these requests translate into about a factor two higher intensity and brightness than the present design performance. In addition to the challenge of producing and accelerating such beams, these parameters affect the resistance of the existing equipment against beam impact. Most of the protection devices in the SPS ring, its transfer lines and the LHC injection areas will be put under operational constraints which are beyond their design specification. The equipment concerned has been reviewed and their resistance to the HL-LHC beams checked. Theoretical and simulation studies have been performed for the SPS beam scraping system, the protection devices and the dump absorbers of the SPS-to-LHC transfer lines, as well as for the LHC injection protection devices. The first results of these studies are reported, together with the future prospects.  
 
MOPFI060 Beam Transfer to LHC with the Low Gamma-transition SPS Optics 419
 
  • G. Vanbavinckhove, W. Bartmann, H. Bartosik, C. Bracco, L.N. Drøsdal, B. Goddard, V. Kain, M. Meddahi, V. Mertens, Y. Papaphilippou, J.A. Uythoven, J. Wenninger
    CERN, Geneva, Switzerland
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
 
  A new low gamma-transition optics with a lower integer tune, was introduced in the SPS to improve beam stability at high intensity. For transferring the beam to the LHC, the extraction bumps, extraction kickers and transfer lines needed to be adapted to the new optics. In particular, the transfer lines were re-matched and re-commissioned with the new optics. The first operational results are discussed for the SPS extraction, the transfer lines and the LHC injection. A detailed comparison is presented between the old and the new optics of the trajectories, dispersion, losses and other performance aspects.  
 
MOPWO032 SPS Scraping and LHC Transverse Tails 957
 
  • L.N. Drøsdal, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, Ö. Mete, B. Salvachua, G. Valentino, E. Veyrunes
    CERN, Geneva, Switzerland
 
  All high-intensity LHC beams have to be scraped before extraction from the SPS to remove the non-Gaussian transverse tails of the particle distributions. The tail particles would otherwise cause unacceptably high losses during injection or other phases of the LHC cycle. Studies have been carried out to quantify the scraping using injection losses and emittance measurements from wire scanners as diagnostics. Beams scraped in the SPS were scraped again in the LHC with collimators to investigate possible tail repopulation. The results of these studies will be presented in this paper.  
 
MOPWO033 Analysis of LHC Transfer Line Trajectory Drifts 960
 
  • L.N. Drøsdal, W. Bartmann, H. Bartosik, C. Bracco, B. Goddard, V. Kain, Y. Papaphilippou, J.A. Uythoven, G. Vanbavinckhove, J. Wenninger
    CERN, Geneva, Switzerland
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
 
  The LHC is filled from the SPS via two 3km long transfer lines. In the first years of LHC operation large trajectory variations were discovered. The sources of bunch-by-bunch and shot-by-shot trajectory variations had been identified and improved by the 2012 LHC run. The origins of the longer term drifts were however still unclear and significant time was spent correcting the trajectories. In the last part of the 2012 run the optics in the SPS was changed to lower transition energy. Trajectory stability and correction frequency will be compared between before and after the optics change in the SPS. The sources of the variations have now been identified and will be discussed in this paper. Remedies for operation after the long shutdown will be proposed.  
 
MOPWO034 Energy Deposition Studies for the Upgrade of the LHC Injection Lines 963
 
  • A. Mereghetti, O. Aberle, F. Cerutti, B. Goddard, V. Kain, F.L. Maciariello, M. Meddahi
    CERN, Geneva, Switzerland
  • R. Appleby
    UMAN, Manchester, United Kingdom
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
 
  The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Given the challenging beam intensities and emittances, a review of the existing beam-intercepting devices is on-going, in order to assess heat loads and consequent thermo-mechanical stresses. Moreover, the exposure of downstream elements to induced shower radiation is assessed. The study is intended to spot possible issues and contribute to the definition of viable design and layout solutions.  
 
TUPFI026 Investigations of the LHC Emittance Blow-Up during the 2012 Proton Run 1394
 
  • M. Kuhn
    Uni HH, Hamburg, Germany
  • G. Arduini, P. Baudrenghien, J. Emery, A. Guerrero, W. Höfle, V. Kain, M. Lamont, T. Mastoridis, F. Roncarolo, M. Sapinski, M. Schaumann, R.J. Steinhagen, G. Trad, D. Valuch
    CERN, Geneva, Switzerland
 
  About 30 % of the potential luminosity performance is lost through the different phases of the LHC cycle, mainly due to transverse emittance blow-up. Measuring the emittance growth is a difficult task with high intensity beams and changing energies. Improvements of the LHC transverse profile instrumentation helped to study various effects. A breakdown of the growth through the different phases of the LHC cycle is given as well as a comparison with the data from the LHC experiments for transverse beam size. In 2012 a number of possible sources and remedies have been studied. Among these are intra beam scattering, 50 Hz noise and the effect of the transverse damper gain. The results of the investigations are summarized in this paper. Requirements for transverse profile instrumentation for post LHC long shutdown operation to finally tackle the emittance growth are given as well.  
 
TUPWO049 Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations 1979
 
  • T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P. Skowroński, R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  • R. Miyamoto
    ESS, Lund, Sweden
 
  The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.  
 
WEPEA053 Progress with the Upgrade of the SPS for the HL-LHC Era 2624
 
  • B. Goddard, T. Argyropoulos, W. Bartmann, H. Bartosik, T. Bohl, F. Caspers, K. Cornelis, H. Damerau, L.N. Drøsdal, L. Ducimetière, J.F. Esteban Müller, R. Garoby, M. Gourber-Pace, W. Höfle, G. Iadarola, L.K. Jensen, V. Kain, R. Losito, M. Meddahi, A. Mereghetti, V. Mertens, Ö. Mete, E. Montesinos, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, M. Taborelli, H. Timko, F.M. Velotti
    CERN, Geneva, Switzerland
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
 
  The demanding beam performance requirements of the HL-LHC project translate into a set of requirements and upgrade paths for the LHC injector complex. In this paper the performance requirements for the SPS and the known limitations are reviewed in the light of the 2012 operational experience. The various SPS upgrades in progress and still under consideration are described, in addition to the machine studies and simulations performed in 2012. The expected machine performance reach is estimated on the basis of the present knowledge, and the remaining decisions that still need to be made concerning upgrade options are detailed.  
 
WEPEA064 SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers 2657
 
  • A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, Ö. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis
    CERN, Geneva, Switzerland
  • R. Appleby
    UMAN, Manchester, United Kingdom
 
  The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.  
 
THPEA040 Design of a Magnetic Bump Tail Scraping System for the CERN SPS 3228
 
  • Ö. Mete, J. Bauche, F. Cerutti, S. Cettour Cave, K. Cornelis, L.N. Drøsdal, F. Galleazzi, B. Goddard, L.K. Jensen, V. Kain, Y. Le Borgne, G. Le Godec, M. Meddahi, E. Veyrunes, H. Vincke, J. Wenninger
    CERN, Geneva, Switzerland
  • A. Mereghetti
    UMAN, Manchester, United Kingdom
 
  The LHC injectors are being upgraded to meet the demanding beam specification required for High Luminosity LHC (HL-LHC) operation. In order to reduce the beam losses which can trigger the sensitive LHC beam loss interlocks during the SPS-to-LHC beam injection process, it is important that the beam tails are properly scraped away in the SPS. The current SPS tail cleaning system relies on a moveable scraper blade, with the positioning of the scraper adjusted over time according to the orbit variations of the SPS. A new robust beam tail cleaning system has been designed which will use a fixed scraper block towards which the beam will be moved by a local magnetic orbit bump. The design proposal is presented, together with the related beam dynamics studies and results from machine studies with beam.  
 
THPWO080 Operational Performance of the LHC Proton Beams with the SPS Low Transition Energy Optics 3945
 
  • Y. Papaphilippou, G. Arduini, T. Argyropoulos, W. Bartmann, H. Bartosik, T. Bohl, C. Bracco, S. Cettour-Cave, K. Cornelis, L.N. Drøsdal, J.F. Esteban Müller, B. Goddard, A. Guerrero, W. Höfle, V. Kain, G. Rumolo, B. Salvant, E.N. Shaposhnikova, H. Timko, D. Valuch, G. Vanbavinckhove, J. Wenninger
    CERN, Geneva, Switzerland
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
 
  An optics in the SPS with lower integer tunes (20 versus 26) was proposed and introduced in machine studies since 2010, as a measure for increasing transverse and longitudinal instability thresholds, especially at low energy, for the LHC proton beams. After two years of machine studies and careful optimisation, the new “Q20” optics became operational in September 2012 and steadily delivered beam to the LHC until the end of the run. This paper reviews the operational performance of the Q20 optics with respect to transverse and longitudinal beam characteristics in the SPS, enabling high brightness beams injected into the LHC. Aspects of longitudinal beam stability, transmission, high-energy orbit control and beam transfer are discussed.