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Non-Linear MD

Non-Linear MD. Motivation for the experiment: The measurement of the dynamic aperture has been an elusive goal for various large proton accelerators.

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Non-Linear MD

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  1. Non-Linear MD • Motivation for the experiment: • The measurement of the dynamic aperture has been an elusive goal for various large proton accelerators. • Taking into account measured or estimated harmonics, power supply ripple etc it has NOT been possible to determine the dynamic aperture experimentally to better than a factor of 2. • Moreover, machine conditions were notstable enough to achieve reliable results (example HERA). • One was obliged to consider a safety factor of 2 for the LHC simulation studies. • At the LHC we have, at last, the chance to benchmark the simulation codes properly: • Good knowledge of harmonics and misalignments • Apparent little noise • Operationally stable • Aperture kicker strong enough for a direct measurement • For the LHC upgrade studies we will not need to consider a safety margin of 2! • Last and not least: request by Yunhai Cai fro SLAC to provide this measurement for the community. • Why now? • We are ready! • Last year the TCDQ could not be taken out severely limiting us. • One of the MD team basically got hardly any data. • The last MD is one year ago and experience of last year seems to indicate that a later date might be risky! LSWG 29.05.2012

  2. Experimental Procedure • Team: M. Giovannozzi, E. Maclean, S. Redaelli, F. Roncarolo, F. Schmidt, E. Todesco, R. Tomás, J. Uythoven, G. Vanbavinckhove, W. Venturini Delsolaro • 1st MD: DA via Intensity Evolution based on Inverse logarithmic scaling law of DA established with tracking data • Technique: Creating Gaussian distribution (damper) and follow intensity over time using MCOs (also alternating signs) to make machine nonlinear • Machine & Tools: Beam1, MO off, probe beam, 1*1010p, wirescanner & synchrotron light monitor, bunch length, BLM, all collimators to 12 s • 2nd MD: Detuning with Amplitude, Resonance Driving Terms, Dynamic Aperture • Technique: Systematic kicks with Aperture kicker (AC-Dipole), nominal + nl chrom knobs + testing skew sextupoles (sign!), collimator out till (>= 12 s) • Goal: Driving Terms till about 10 s, beyond 10 s changing kick in small steps until losses become relevant • Machine & Tools:Beam2,probe beam, 2 µm, 2 bunches à 1*1010p, Aperture Kicker (>= 12 s, MPP fully involved!), AC-Dipole, wirescanner, BPM, BLM LSWG 29.05.2012

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