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Operational challenges ( Feed forward from Evian LHC operation workshop)

Operational challenges ( Feed forward from Evian LHC operation workshop). 7-9 December 2010 Day after last beam Two nights – 7 sessions. Evian – Sessions . LHC beam operation: review of 2010 and setting the scene for 2011

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Operational challenges ( Feed forward from Evian LHC operation workshop)

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  1. Operational challenges(Feed forward from Evian LHC operation workshop) 7-9 December 2010Day after last beamTwo nights – 7 sessions Evian summary

  2. Evian – Sessions • LHC beam operation: review of 2010 and setting the scene for 2011 • Experiments, efficiency, beam from injectors, 75 & 50 ns, intensity ramp up, RF • Driving the LHC • Turnaround, software, magnetic model, missing functionality • Beam diagnostics and feedback systems • Bunch by bunch, feedbacks, transverse damper, BPMs, transverse beam size Evian summary

  3. Evian – Sessions • Machine protection systems • MPS performance, LDBS, abort gap, minimum beta*, injection protection, the human factor • Beam losses • Collimation, injection, extraction, UFOs, BLM thresholds • Luminosity performance & wrap-up • Emittance preservation, the hump, beam-beam, luminosity optimization, optics, pushing the limits in 2011, 2011 projections Evian summary

  4. Sessions 1 & 2: Operations 2010: pretty good going Operations bedded in but there is room for improvement • Improved machine availability • Turn around optimization • Beam quality and availability from injectors • Machine safety & the human factor • Software and controls • Magnet model • For all these: lessons learnt, improvements being made Evian summary

  5. Beam quality and availability from the injectors Transverse and longitudinal characteristics very important • Clear procedures needed (scraping, blow-up etc.) • Preparation in good time, check lists • Must be able to track beam quality through the injectors • Emittances, intensities etc. • LHC request must be clearly communicated in good time • Talk to your suppliers • Nice long list of RF improvements in the SPS • Dedicated LHC filling to be pursued Giulia Papotti Evian summary

  6. Magnetic model/cycle and its effects ..today we have the most complex and comprehensive field forecast system ever implemented in a superconducting accelerator Luca Bottura 2008 • Go dynamic with b3 compensation at injection • ~2 units of decay, as expected by FiDeL, but on much longer time constant • Measure & deploy dynamic correction. • Rollback decay driven trims before starting each injection • Tune decay at injection • Remove hysteresis handling in squeeze • Ramp-down settings for access to avoid pre-cycle afterwards • Chromaticity during ramp • Tracked within ±7 units – we can improve the initial part EzioTodesco Evian summary

  7. The human factor Resources • LHC: • 5.4 GCHF investment • Around 299MCF/year P & M budget • Understandable desire to capitalize on investment • Route 1: long operational years • Human factor: • Operations and infrastructure teams with limited manpower • Stretched in some areas - not only the LHC Evian summary

  8. S3: RF, beam diagnostics and feedback systems Key systems have performed with a remarkable degree of maturity – inevitably some improvements possible: Beam based feedbacks – tune, orbit Transverse feedback RF Beam instrumentation: BPMs, BLMs, beam size measurement… • Interaction of Q-feedback and TFB • BPMs in interaction region • BPM intensity dependence • Reliable bunch by bunch beam size measurement through the cycle Evian summary

  9. Transverse Feedback • commissioned damper at 450 GeV, during ramp and with colliding beams • nominal damping rate reached and surpased • commissioned operation with bunch train • commissioned damper for ions at 450 GeV and with colliding ion beams • abort gap cleaning and injection slot cleaning successfully used • diagnostics (logging, fixed display, multi-bunch acquisition) available • Lots incoming in 2011 • Tune measurement options listed. Strategy to be defined. Wolfgang Hofle Evian summary

  10. Tune, Orbit feedbacks • Feedbacks performed well and facilitated a fast commissioning • de-facto required during every ramp and squeeze with nominal beam and expect the same also for next year • additional safety margin to operation provided feed-forward is performed regularly • Good overall performance with little transmission losses and minimal hiccups related to Q/Q' instrumentation, diagnostics and Q/Q' & orbit feedbacks • This year's 1% losses may become more critical in 2011 Ralph Steinhagen Evian summary

  11. Tune feedback in the ramp Evian summary

  12. BBQ versus ADT Effective ADT noise floor and observed bunch-to-bunch cross-talk hinders reliable operation of LHC's Q/Q’-diagnostics and related feedbacks Evian summary

  13. Scenario for gain Evian summary

  14. BPMs: status, measurement reliability and outlook for 2011 • The global performance of the system is very good – 97% channel availability • Number of improvements through the year • including temperature calibration/compensation • Synchronous mode 2011 • will solve double trigger issue on IR BPMs • Orbit on selected bunches • IR BPMs: cable adapters will be installed this XMAS stop • Pre-flight checks with beam • Testing acquisition and calibration • Intensity dependence cross-over • B1 behavior was caused by a small impedance mismatch at the input of the intensity module. • Replacing the intensity card by termination card in IRs Eva Calvo Evian summary

  15. Transverse beam size F. Roncarolo Essential - need bunch by bunch - getting there • Wire scanners • Turn and bunch-to-bunch • Reference but take care • BSRT • DC and pulsed mode • Resolution – optics; • Accuracy via x-calibration with WS – correction factors not stable • Absolute calibration and ultimate resolution: still to be studied • Complicated in ramp – change of focusing etc. • Bunch by bunch, turn by turn incoming – fast camera • BGI is in commissioning phase • relative accuracy reliable once beam profile quality has been checked • absolute calibration to be studied to complement cross-calibration with bumps • 2011: gas inj. remote control, better camera control Evian summary

  16. S4: Machine protection Machine protection system has functioned remarkably well – long list of improvements for 2011 LBDS performing well Injection protection – some issues Intensity ramp up strategy in 2010 was well judged Motherhood statement: continue to take it seriously Injection protection - injecting unsafe beam into the LHC Enforcing a more rigorous approach at injection > 500 kJ Ramping up intensity – clear strategy for 2011 required Evian summary

  17. Main challenges during 2010 run (> injection) Beam dumps as a function of beam mode for fills where energy ramp started and main causes of loosing the beams… SIS (TCDQ Position, missing energy) Magnet Powering (Orbit Feedback, etc..) Collimator interlocks during ramp >> Fast Losses (UFOs) Magnet Powering (QPS, CRYO, PC,.. ) SW Permit (Orbit, BLM lost in IR7…) Electrical Perturbations Magnet Powering (OFB/QFB, QPS sector trip, ..) Loss Maps, Collimator setup, Fast losses ATLAS Magnet Powering (Mostly PC issues + FB, CRYO,..) Fast losses, loss maps,… SW Permits (TCDQ position, trip of DOCs) Loss maps, wire scanner tests, collimators moving… SW Permits (TCDQ position,…) Magnet Powering (Mostly PC issues, …)

  18. MPS system response - summary LHC Machine Protection Systems have been working extremely well during 2010 run thanks to a lot of commitment and rigor of operation crews and MPS experts Most failures are captured before effects on beam are seen, still no quenches with circulating beam (with ~ 30MJ per beam and 10mJ for quenching a magnet) Beam dumps above injection are rigorously analyzed, we can do better at injection (avoiding repetitive tries without identifying the cause) Still a lot of room for improving tools for more efficient and automated analysis No evidence of major loopholes or uncovered risks, but bypassing of protection layers was/is still possible -> Follow-up of MPS Review recommendations Still wehave to remain vigilant to maintain current level of dependability of MPS systems, especially when entering longer periods of ‘stable running’ Markus Zerlauth Evian summary

  19. LBDS: Faults Occurred During 2010 run • 1 energy tracking error at 3.5 TeV due to instabilities of 35 kV power supplies  beam dump (30/03/2010: media day) • Asynchronous beam dump, during energy scan without beam (due to spark on the outside of the gate turn-off GTO thyristor): • 1 at 5 TeV • 2 at 7 TeV • 4 internal triggers due to vacuum interlocks on the MKB for B2 • FALSE vacuum pressure reading – logic now changed to use only VAC signal • 1 Asynchronous beam dump with beam • 2 beam dumps induced by TCDQ faults Safe margin for 3.5 TeV operation, isolators implemented during technical stops (starting in January 2011  finished during 2012 TS) Number of total dump system failures (unacceptable):1 every 1000000 years Chiara Bracco

  20. LBDS • LBDS failures occurrence in agreement and not worse than requirements and expectations • No damage or quench during synchronous and asynchronous beam dumps • Leakage to downstream elements within specifications • TCDQ needs TLC – long-term plans to define • Machine protection validation tests, procedures and tests frequency: • Is this adequate? (too often, too rarely) • Could tests be improved? • Do they really insure machine safety? Chiara Bracco Evian summary

  21. Excellent performance of collimation system- no quenches BLMs – great job – thresholds always a consideration Issues at injection with fast losses Watch extraction losses UFOs BLM thresholds at critical locations BEAM losses Evian summary

  22. Losses away from collimators: statistics and extrapolation • UFOs • Triplet, IRs and arcs • Scaling with total intensity – extrapolations look worrying • Don’t appear to get harder with intensity • Loss duration falls with intensity • Interestingly – hot and cold regions out there • Maximize UFO acceptance by threshold adjustment • BLM hardware failures • Acceptable! Barbara Holzer Evian summary

  23. BLM thresholds Detailed analysis presented by Annika! Correlations between collimator movements, vacuum and beam losses Annika Nordt Evian summary

  24. Excellent performance Stability and reproducibility: orbit, optics Intensity and emittance from injectors Benign beam-beam Collimation has performed very well – projected limits for beta* presented. No limits on beam intensity in 2011. Optics – measurement and correction Emittance preservation through the cycle – the hump Bunch by bunch diagnostics Beam quality from injectors: intensity, emittance Luminosity calibration Beam-beam LUMINOSITY performance Evian summary

  25. Optics Rogelio Tomas Garcia • Beating at injection, during squeeze well corrected • 3.5 m. • 10% achieved! • Slightly worse with LSA… not driving IR3,4,6 and 7 • Hysteresis handling – 10% beating at 1.5 m. – we will desist • Excellent long-term stability! • Non-negligible drift 8% observed at injection • Beatings going to get worse, but correctable • IR coupling correction mandatory below 2 m. Evian summary

  26. The hump is there all the time • The hump affects luminosity performance due to blow-up (particularly at 450 GeV). In collision it can excite beam-beam coherent modes or generate tails and therefore losses • Mitigation: low noise TFB at maximum gain • Since middle of November turn-by-turn/bunch-by-bunch position with damper pick-up. Ion filling scheme with basic spacing of 500 ns possibility of determining the frequency of the hump ±f0+n x 2 MHz with 0<f0<1 MHz • fhump < 10 MHz • The identification (and possibly eradication) of the origin remain the (challenging) goal of the ongoing analysis and measurements. Gianluigi Arduini Evian summary

  27. The hump is there all the time Evian summary

  28. Energy? Squeezing further - minimum beta* LHCb ”Luminosity leveling”, beta’s at Alice and LHCb 150 vs. 75 vs. 50 ns. - beam from injectors, start-up strategy Electron cloud: heat load, vacuum, scrubbing, monitoring UFOs R2E Beam-beam – pushing the limits 2011 INCOMING All to be covered in detail at this workshop Evian summary

  29. Conclusions • Come a phenomenally long way in 9 months • Notable feature - remarkable maturity of some key systems after just a year • It hasn’t come for free • It’s been years in the preparation • Devil is, as always, in the details, lots to follow-up • Possible improvements, consolidation detailed for all systems • 2011 clearly aims to leverage off of what’s been learnt this year • With some known problems incoming: • UFOs, electron cloud, R2E… • We’ll be pushing up Ralph’s stored energy plot • LET’S TRY NOT TO BREAK IT! Evian summary

  30. Acknowledgements • Chairpersons • Roger, Gianluigi, Jorg, Brennan, Ralph, Malika • Scientific secretaries • Giulia, Mirko, Reyes, Alick, Stefano, Verena • Speakers • Lot of hard work at the end of a hard year • Workshop secretariat • Sylvia Dubourg, Flora Meric • Technical support • Pierre Charrue • Brains, organization and determination • MalikaMeddahi • Editor of proceedings • Brennan Goddard • Steve and Paul for their support Evian summary

  31. Special thanks…. • ATLAS: highlights from the first run • FabiolaGianotti • ALICE: The 2010 LHC Experience • Werner Riegler, on behalf ofJurgenSchukraft • CMS 2010 and Prospects for 2011-12 • TizianoCamporesi, on behalf of Guido Tonelli • Compliments to LHC from LHCb • Andrei Golutvin Very much appreciated! Evian summary

  32. Thanks to CMS Evian summary

  33. Evian summary

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