Author: Macpherson, A.
Paper Title Page
TUPME060 Tune Studies with Beam-Beam Effects in LHC 1703
  • S. Paret, J. Qiang
    LBNL, Berkeley, California, USA
  • R. Alemany-Fernandez, X. Buffat, R. Calaga, K. Cornelis, M. Fitterer, R. Giachino, W. Herr, A. Macpherson, G. Papotti, T. Pieloni, S. Redaelli, F. Roncarolo, M. Schaumann, R. Suykerbuyk, G. Trad
    CERN, Geneva, Switzerland
  • R. Miyamoto
    ESS, Lund, Sweden
  Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
In high brightness colliders, the tune spread due to the collisions has a significant impact on the quality of the beams. The impact of the working point on emittance growth and beam lifetime has been observed in beam experiments in LHC. Strong-strong beam-beam simulations that were accomplished to better understand such observations are shown. Compared to experiments, wide ranged parameter scans can be done easily. Tune footprints and scans of the emittance growth obtained from simulations are discussed. Three cases are considered: Very high intensity, moderate intensity and collisions with separated beams.
WEPEA046 Experimental Observations from the LHC Dynamic Aperture Machine Development Study in 2012 2606
  • M. Giovannozzi, S. Cettour Cave, R. De Maria, M. Ludwig, A. Macpherson, S. Redaelli, F. Roncarolo, M. Solfaroli Camillocci, W. Venturini Delsolaro
    CERN, Geneva, Switzerland
  In view of improving the understanding of the behaviour of the dynamic aperture and to benchmark the numerical simulations performed so far, two experimental sessions have been scheduled at the LHC. The observations of the first sessions have been reported elsewhere[1], while in this paper the latest observations in terms of beam currents, blm losses and beam sizes will be described. The octupolar spool pieces have been used to artificially reduce the dynamic aperture and then induced slow beam losses. Alternating signs have been used in order to probe different configurations. Finally, scans over the strength of the decapolar spool pieces have been performed too.
[1] M. Giovannozzi et al., “First Experimental Observations from the LHC Dynamic Aperture Experiment”, in proceedings of IPAC12, p. 1362