Author: Bohl, T.
Paper Title Page
TUPME034 Experimental Studies for Future LHC Beams in the SPS 1652
  • H. Bartosik, T. Argyropoulos, T. Bohl, S. Cettour-Cave, J.F. Esteban Müller, W. Höfle, G. Iadarola, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko
    CERN, Geneva, Switzerland
  • A.Y. Molodozhentsev
    KEK, Ibaraki, Japan
  The High Luminosity LHC (HL-LHC) project requires significantly higher beam intensity than presently accessible in the LHC injector chain. The aim of the LHC injectors upgrade project (LIU) is to prepare the CERN accelerators for the future needs of the LHC. Therefore a series of machine studies with high brightness beams were performed, assessing the present performance reach and identifying remaining limitations. Of particular concern are beam loading and longitudinal instabilities at high energy, space charge for beams with 50ns bunch spacing and electron cloud effects for beams with 25ns bunch spacing. This paper provides a summary of the performed studies, that have been possible thanks to the implementation of the SPS low gamma-transition optics.  
TUPME046 Performance of SPS Low Transition Energy Optics for LHC Ion Beams 1667
  • F. Antoniou, G. Arduini, H. Bartosik, T. Bohl, S. Cettour Cave, K. Cornelis, D. Manglunki, Y. Papaphilippou
    CERN, Geneva, Switzerland
  An optics with low transition energy has been developed in the SPS for removing intensity limitations of the LHC proton beam and has become operational towards the second part of the 2012 LHC proton run. This optics was also used for filling the LHC with lead ions during the p/Pb run of the beginning of 2013. The impact of this optics in the performance of the LHC ion beam is studied here, especially with respect to collective effects, at the SPS injection energy. In particular, the potential gain of the increased beam sizes provided by this optics, with respect to losses and emittance blow up due to space-charge and Intrabeam Scattering (IBS) is evaluated. The measured lifetime is compared with the one provided by the Touschek effect and its interplay with RF noise is studied. The models are supported by measurements in the SPS and in the LHC flat bottom.  
TUPWA039 Identification of the SPS Impedance at 1.4 GHz 1793
  • T. Argyropoulos, T. Bohl, H. Damerau, J.F. Esteban Müller, E.N. Shaposhnikova, H. Timko
    CERN, Geneva, Switzerland
  In the SPS spectrum measurements of very long single bunches were used in the past to identify sources of longitudinal microwave instability. Shielding of the identified objects significantly improved the beam stability. However, longitudinal instabilities are still one of the limitations for high intensity LHC beams in the SPS. Recently the same measurement technique was used again, revealing a strong high frequency resonance. During the slow de-bunching with the RF switched off, the presence of different resonant impedances leads to a line density modulation at the resonant frequencies. Longitudinal profiles of bunches of various intensities were acquired. For sufficiently high intensities their spectra show a fast growing and strong modulation at 1.4 GHz. Measurements using two transverse optics with different transition energy are compared. Reproducing the measurements with numerical simulations, including the known SPS longitudinal impedances, allowed the parameter range of this unknown source to be determined. Possible candidates as impedance sources in the SPS ring are investigated.  
TUPWA049 Short High-Intensity Bunches for Plasma Wakefield Experiment AWAKE in the CERN SPS 1820
  • H. Timko, T. Argyropoulos, H. Bartosik, T. Bohl, J.F. Esteban Müller, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  • A.V. Petrenko
    BINP SB RAS, Novosibirsk, Russia
  Obtaining the shortest possible bunch length in combination with the smallest transverse emittances and highest bunch intensity – this is the wish list of the proton-bunch driven, plasma wakefield acceleration experiment AWAKE currently under feasibility study at CERN. A few measurement sessions were conducted to determine the achievable bunch properties and their reproducibility. To obtain a short bunch length, the bunches were rotated in longitudinal phase space using the maximum available RF voltage prior to extraction. Measurements were carried out in two optics with different transition energies. The main performance limitation is longitudinal beam instability that develops during the acceleration ramp. With lower transition energy, beam stability is improved, but the bucket area is smaller for the same voltage. Based on the results obtained, we shall discuss the choice of optics, the impact of longitudinal instabilities, the importance of reproducibility, as well as options for improving the bunch parameters.  
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.  
WEPEA060 Plans for the Upgrade of CERN's Heavy Ion Complex 2645
  • D. Manglunki, M. E. Angoletta, H. Bartosik, A. Blas, D. Bodart, M.A. Bodendorfer, T. Bohl, J. Borburgh, E. Carlier, J.-M. Cravero, H. Damerau, L. Ducimetière, A. Findlay, R. Garoby, S.S. Gilardoni, B. Goddard, S. Hancock, E.B. Holzer, J.M. Jowett, T. Kramer, D. Kuchler, A.M. Lombardi, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille
    CERN, Geneva, Switzerland
  To reach a luminosity higher than 6×1027 Hz/cm2 for Pb-Pb collisions, as expected by the ALICE experiment after its upgrade during the 2nd Long LHC Shutdown (LS2), several upgrades will have to be performed in the CERN accelerator complex, from the source to the LHC itself. This paper first details the present limitations and then describes the strategy for the different machines in the ion injector chain. Both filling schemes and possible hardware upgrades are discussed.  
WEPEA061 The First LHC p-Pb run: Performance of the Heavy Ion Production Complex 2648
  • D. Manglunki, M. E. Angoletta, H. Bartosik, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, C. Carli, E. Carlier, S. Cettour Cave, K. Cornelis, H. Damerau, A. Findlay, S.S. Gilardoni, S. Hancock, J.M. Jowett, D. Kuchler, M. O'Neil, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille, B. Vandorpe, U. Wehrle, J. Wenninger
    CERN, Geneva, Switzerland
  TThe first LHC proton-ion run took place in January-February 2013; it was the first extension to the collider programme, as this mode was not included in the design report. This paper presents the performance of the heavy ion and proton production complex, and details the issues encountered, in particular the creation of the same bunch pattern in both beams.  
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.