Keyword: beam-beam-effects
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MOPWA050 Beam Dynamics Studies to Develop a High-energy Luminosity Model for the LHC simulation, luminosity, collider, emittance 233
 
  • G. Campogiani
    Rome University La Sapienza, Roma, Italy
  • Y. Papaphilippou
    CERN, Geneva, Switzerland
  
  Funding: support provided by the EPS-AG through the EPS-AG student grant program
Luminosity, the key figure of merit of a collider as the LHC, depends on the brightness of the colliding beams. This makes the intensity dependent beam-beam effect the dominant performance limiting factor at collision. The parasitic interactions due to the electromagnetic mutual influence of the beams in the interaction region of a collider induce a diffusive behaviour in the tails of the beam. The evolution of charge density distribution is studied to model the beam tails evolution in order to characterize beam lifetime and luminosity. To achieve this, tools are developed for tracking distributions of arbitrary number of single particles interacting with the opposing strong-beam, to analyse the halo formation processes due to the combined effect of beam-beam and machine non-linearities. This paper presents preliminary results of the simulations, both for the LHC Run I and nominal LHC parameters. The former will be used to benchmark simulations while the latter aims at supporting luminosity estimate for the Run II. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA050  
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MOPMA022 Numerical Analysis of Parasitic Crossing Compensation with Wires in DAΦNE positron, luminosity, collider, experiment 589
 
  • A. Valishev
    Fermilab, Batavia, Illinois, USA
  • C. Milardi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: This work was partially supported by the US LARP. The HiLumi LHC Design Study is partially funded by the European Commission Grant Agreement 284404.
Current bearing wire compensators were successfully used in the 2005-2006 running of the DAΦNE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DAΦNE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA022  
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MOPMN015 Simulation of Beam-Induced Plasma for the Mitigation of Beam-Beam Effects plasma, proton, simulation, electron 734
 
  • J. Ma, V. Samulyak, K. Yu
    SBU, Stony Brook, New York, USA
  • V. Litvinenko, V. Samulyak, G. Wang
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • V. Samulyak
    SUNY SB, Stony Brook, New York, USA
  
  One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN015  
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TUPTY073 An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation luminosity, optics, simulation, electron 2199
 
  • S.D. Fartoukh
    CERN, Geneva, Switzerland
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
  • A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Research supported by DOE via the US-LARP program and by EU FP7 HiLumi LHC - Grant Agreement 284404
In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical β* values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyse it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY073  
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TUPTY076 Beam-Beam Simulation of Crab Cavity White Noise for LHC Upgrade luminosity, cavity, simulation, emittance 2206
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • J. Barranco García
    EPFL, Lausanne, Switzerland
  • K. Ohmi
    KEK, Ibaraki, Japan
  • T. Pieloni
    CERN, Geneva, Switzerland
  
  High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the crab cavity noise on the beam luminosity lifetime based on strong-strong beam-beam simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY076  
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TUPTY077 Strong-Strong Beam-Beam Simulation of Bunch Length Splitting at the LHC simulation, emittance, synchrotron, resonance 2210
 
  • J. Qiang, S. Paret
    LBNL, Berkeley, California, USA
  • K. Ohmi
    KEK, Ibaraki, Japan
  • T. Pieloni
    CERN, Geneva, Switzerland
  
  Longitudinal bunch length splitting was observed for some LHC beams. In this paper, we will report on the study of the observation using strong-strong beam-beam simulations. We explore a variety of factors including initial momentum deviation, collision crossing angle, synchroton tune, chromaticity, working points and bunch intensity that contribute to the beam particle loss and the bunch length splitting, and try to understand the underlying mechanism of the observed phenomena.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY077  
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