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Simultaneous Orbit, Tune, Coupling, and Chromaticity Feedback in RHIC

This paper discusses the motivation for and implementation of improved ramp development efficiency, precision measurement, and control of beam parameters, as well as improved reproducibility of accelerator conditions in RHIC. It includes examples of tune and coupling feedback measurements and the design and implementation of global orbit and chromaticity feedback systems.

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Simultaneous Orbit, Tune, Coupling, and Chromaticity Feedback in RHIC

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  1. Simultaneous orbit, tune, coupling, chromaticity feedback in RHIC MOTIVATION improved ramp development efficiency precision measurement and control of beam parameters improved reproducibility of accelerator conditions TIME Meeting, M. Minty, April 13, 2010

  2. RHIC tune and coupling feedback measurement based on direct-diode detection for precision measurements - M. Gasior , R. Jones (2005) feedback design distinguishes between eigenmodes - R. Jones, P. Cameron, Y. Luo (2005) implementation demonstrated at RHIC in 2006 - P. Cameron et al (2006) made operational (2009) hardware - T. Curcio, C. Dawson, C. Degen, Y. Luo, K. Mernick, T. Russo, R. Schroeder, M. Wilinski software – A. Marusic + operations support - notably G. Marr, B. Martin, and V. Schoefer 7 ramps to establish blue beams to 250 GeV (02/14-15/09) 4 additional ramps to establish both beams to 250 GeV (02/15-16/09) with ramp efficiencies of 99.6% and 97.9% respectively < 1 shift per new optics by end of run TIME Meeting, April 13, 2010

  3. RHIC tune and coupling feedback – example RUN08 RUN09 TUNES COUPLING (note factor 3 scale change wrt RUN08 TIME Meeting, April 13, 2010

  4. Global orbit feedback at RHIC (new, 2010) measurement based on existing beam position monitors using new and improved algorithm for measuring average orbit – R. Michnoff (2009) using original survey (e.g. offset) data – T. Satogata deterministic data delivery – A. Marusic, R. Michnoff, R. Hulsart feedback design orbit correction algorithm (“singular valued decomposition”) by V. Ptitsyn extended to application at 1 Hz rate during energy ramp – G. Robert-Demolaize implementation new ADO manager for gathering data, computing and distributing corrections – A. Marusic ramp-down and feed-forward of corrections – A. Marusic TIME Meeting, April 13, 2010

  5. RHIC global orbit feedback – convergence tests at injection energy: 1) “randomize” orbits 2) measure rms of BPM readings as feedback is engaged blue ring yellow ring Xrms Yrms Xrms Yrms uses ~ 150 beam position measurements and ~120 correctors in each plane: horizontal (x) and vertical (y) in the blue and yellow rings) TIME Meeting, April 13, 2010

  6. RHIC chromaticity feedback (new, 2010) measurement based on existing beam position monitors + rf frequency modulation based on S. Tepikian’s improved algorithm for measurement of chromaticity feedback design and implementation feedback algorithm, ramp-down and feed-forward of corrections – A. Marusic run09 run10 xx xy xx xy Qx Qx Qy Qy TIME Meeting, April 13, 2010

  7. RHIC simultaneous orbit, tune+coupling, and chromaticity feedback 04/08/10 – 39 GeV, Au107 feed-forward feedback settings 09:50 – prepare orbits at injection energy Blue Ring <x> ~ 600 m (dispersive orbit) xrms~ 150 m yrms~ 150 m initial conditions for energy ramp <y> = 0 engage orbit feedback disengage orbit feedback and ramp down activate TIME Meeting, April 13, 2010

  8. 10:40 – first ramp of both beams to store energy with all feedbacks ORBITS TUNES blue ring blue ring COUPLING CHROMATICITY blue ring blue ring TIME Meeting, April 13, 2010

  9. 10:40 – first ramp 11:46 – second ramp TUNES blue ring blue ring CHROMATICITY blue ring blue ring ramp efficiencies: 98% blue (6 bunches) 98% yellow (6 bunches) ramp efficiencies: 33% blue (6 bunches) 99% yellow (6 bunches) TIME Meeting, April 13, 2010

  10. 12:32 – third ramp 13:36 – fourth ramp TUNES blue ring blue ring rf frequency modulation intentionally off CHROMATICITY blue ring ramp efficiencies: 91% blue (111 bunches) 99% yellow (111 bunches) ramp efficiencies: 100% blue (17 bunches) 100% yellow (23 bunches) TIME Meeting, April 13, 2010 TIME Meeting, April 13, 2010

  11. CREDITS (time frame of RUN10) BBQ upgrade – M. Wilinski, A. Marusic, C. Dawson, K. Mernick, T. Curcio, A. Weston chromaticity feedback – A. Marusic, S. Tepikian orbit feedback – V. Ptitsyn, A. Marusic, G. Robert-Demolaize, T. D’Ottavio BPMs – R. Michnoff, R. Hulsart, P. Cerniglia, A. Marusic, T. Satogata operations – all for active participation operations – particularly G. Marr and V. Schaefer for support in implementation and in performance assessments … and Al Marusic for just about everything and especially the very complex development histories available at http://www.cadops.bnl.gov/Instrumentation/InstWiki/index.php/Machine_Development_and_APEX,_Run-10 TIME Meeting, April 13, 2010

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