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MD: Variable Transverse Damper Gain, Tune Measurement and Emittance Preservation

MD: Variable Transverse Damper Gain, Tune Measurement and Emittance Preservation First look at results – ADT part –  s ee presentation by V. Kain on emittance preservation. W. Hofle. Participants: D. Valuch , W. Hofle , F. Dubouchet , V. Kain , M. Kuhn,

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MD: Variable Transverse Damper Gain, Tune Measurement and Emittance Preservation

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  1. MD: Variable Transverse Damper Gain, Tune Measurement and Emittance Preservation • First look at results – ADT part – •  see presentation by V. Kain on emittance preservation W. Hofle Participants: D. Valuch, W. Hofle, F. Dubouchet, V. Kain, M. Kuhn, F. Roncarolo, M. Gasior, R. Steinhagen LHC MSWG

  2. Original Planning 2012 MD#1 (WARNING: Details will be adjusted due to commissioning progress and issues arising) see Mariusz 2 hours, 450 GeV Probe, CANCELLED • Fri • 06:00 – 07:00: end of fill study (tune scan, levelling, …) • 09:00 – 12:00: 450 GeV: Longitudinal impedance • 12:00 – 18:00: 450 GeV 4 TeV: ADT (incl. fast blow-up test) • 20:00 – 02:00: 450 GeV: BI (FBCT and BPM’s) • Sat • 04:00 – 12:00: 450 GeV 4 TeV: Collimation • 14:00 – 22:00: 450 GeV: Injection: beam loss limitations towards nominal intensity • 00:00 – 08:00: 450 GeV 4 TeV: Aperture at the triplets • Sun • 10:00 – 18:00: 450 GeV: RF batch by batch blow-up • 18:00 – 23:00: 450 GeV 4 TeV: BI (emittance cross calibration with ADT blowup) • 01:00 – 06:00: 450 GeV 4 TeV: ADT (tune compatibility)  Saturday consequence: only one ramp for ADT-gain part LHC MSWG

  3. ADT through the cycle LSA:0.25 LSA:0.02 D. Valuch @ Evian 2011 LHC MSWG

  4. Saturday: summary • damping time verification 50 ns (LSA 0.25), SB (LSA 0.25 and 0.02) • gain observation experiment HI-LO-HI at 450 GeV • gain modulation: 0, 1, 2, 5, 12, 30, 70, 127, commissioned at 450 GeV • ramp with gain modulation of 8 bunches, leading bunch higher intensity all done as planned

  5. Saturday, April 21, 2012, ADT 4 hours Part 1: 1.5 hours (scheduled) • first checked damping time in single bunch mode for high gain and low gain (0.25 and 0.02 in LSA)  follow-up of difference between the two planes and beams during technical stop  2 amplifiers (of 16) changed, and another 8 new tetrodes installed, 1 tetrode moved between amplifiers, more gain after technical stop, more peak kick strength (Gino Cipolla, F. Killing, D. Valuch) • injected one nominal bunch (1.4-1.5x10**11) and waited about 40 minutes at 450 GeV observing emittances; 12 minutes with high gain, 11 minutes with low gain and 10+ minutes with high gain  emittance data  see V. Kain’s analysis • damping times: • (ratio high / low gain in LSA: 12.5; filamentation significant for low gain setting ! • single bunch mode at high gain between  11 and 19 turns • single bunch mode at low gain between  73 and 127 turns • 50 ns settings high gain (expected 3x slower than single b. setting)  35 to 51 turns LHC MSWG

  6. Saturday, April 21, 2012, ADT 4 hours Part 2: 2.5 hours • commissioned batch-by-batch gain modulation factor of 0-127 in steps of 1 • 8 bunches injected with gains of ADT scaled by (0, 1, 2, 5, 12, 30, 70, 127)/128 • verified by observing injection damping ADT gain modulation commissioned thanks to hard work by D. Valuch and software team Q7 Q9 Q7 Q9 bunch 1 gain 0 Bunch 3 gain 2 Q9 Q7 Q9 Q7 bunch 1 gain 12 Bunch 8 gain 127 g gain 12  approx. prepare for ramp (LSA 0.02) gain 127  high gain (LSA 0.25, injection setting) first 4096 turns of the horizontal beam 1 injection oscillations are shown LHC MSWG

  7. Saturday, April 21, 2012, ADT 4 hours Part 2: 2.5 hours • ramped with normalisedLSA gain at 0.25 at all times + gain modulation •  gain saturates in early part of ramp, but modulation stays in and is active • LSA gain of 0.02 normally used in “prepare for ramp” corresponds to bunch 5 approx. • emittances and blow-ups  see V. Kain • better BBQ signal than we would have had with high gain and without modulation • thanks to low gain bunches (also higher intensity for bunch 1 as planned) • emittance data to be analysed (large scatter observed) • also recorded all bunches of HB1Q7 with new “continuous acquisition” in ADT • batch-by-batch gain mod. is feasible for Physics fill to see which gain gives highest lumi 1 of 8 bunches no gain 8 bunches high gain LHC MSWG

  8. Monday a.m.: summary Ramp 1 with gain modulation and 8 bunches, equal intensity 0, 1, 2, 5, 12, 30, 70, 127 logging of data from pick-ups and damper logging issue (DFS space full), switch from DFS to local PC in SR4 for logging Ramp 2 2 x 12 bunches, 1st batch 1.4x10**11, 2nd batch 1.1x10**11 LSA gain 0.25; 50 ns settings; gains 5, 127 recorded 4xDSPU (all planes and beams) data (Q7s) done as planned some issues with logging of ADT data via matlab scripts dedicated software to efficiently Continue these MDs (style like hump buster)

  9. Data analysis - status Emittances: Verena see her presentation, thorough analysis, excellent ADT tune data: analysis pending Data from BBQ: collaboration with BI for analysis for these fills ?!

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