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Roderik Bruce Beams Department, Accelerator and Beam Physics Group On behalf of the LHC team

LHC machine status report. Roderik Bruce Beams Department, Accelerator and Beam Physics Group On behalf of the LHC team LHCC 12/09/2018

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Roderik Bruce Beams Department, Accelerator and Beam Physics Group On behalf of the LHC team

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  1. LHC machine status report Roderik Bruce Beams Department, Accelerator and Beam Physics Group On behalf of the LHC team LHCC 12/09/2018 Thanks for input and material: E. Bravin, S. Claudet, M. Giovannozzi, G. Iadarola, J. Jowett, A. Lechner, E. Metral, D. Nisbet, S. Redaelli, C. Schwick, J. Uythoven, J. Wenninger

  2. Contents • Status and reminder from last LHCC • Operational achievements • Availability, faults and limitations • Status of luminosity production • Outlook on the rest of the year R. Bruce, LHCC 2018.09.12

  3. 2018 LHC timeline Previous LHCC Time period covered by R. Steerenberg at previous LHCC TS1 MD1 β*=90 m VdM TS2 13 TeVpp physics MD2 MD3 Today R. Bruce, LHCC 2018.09.12

  4. Status at previous LHCC • Very efficient commissioning • reached full number of bunches ahead of schedule • Very good start of production • promising slope of integrated luminosity • Important last year before LS2 • Official goal of 60 fb-1 over the year in ATLAS/CMS, 2 fb-1 for LHCb • Some beam dumps due to 16L2 events R. Bruce, LHCC 2018.09.12

  5. What has happened since May? • In general, good production achieved • Established very good peak performance • Excellent production achieved in certain periods • Production is on track for the yearly goal • Time lost due to faults - sometimes a rocky ride • A few faults caused several days downtime • Minor faults causing unforeseen dumps, making luminosity production less efficient R. Bruce, LHCC 2018.09.12

  6. Contents • Status and reminder from last LHCC • Operational achievements • Availability, faults and limitations • Status of luminosity production • Outlook on the rest of the year R. Bruce, LHCC 2018.09.12

  7. Beam parameters achieved • Established very good performance. Typical values: R. Bruce, LHCC 2018.09.12

  8. Optimized running scenario • Changing both crossing angle and β* through leveling while in stable beams • Scenario optimized under a number of constraints Start of fill Later in fill – lower intensity R. Bruce, LHCC 2018.09.12

  9. Fill 7127, September 5 Typical recent fill • Peak lumi: ~2×1034 cm-2s-1 • Twice LHC design luminosity! • Continuous crossing anti-leveling • β*-leveling in two steps towards end of fill • End point: 25 cm • Lowest β* ever in the LHC for physics! • If not dumped prematurely, ~0.5 fb-1produced per fill ATLAS/CMS time (h) time (h) time (h) R. Bruce, LHCC 2018.09.12

  10. Very good production in some periods • Example: Reached almost 1 fb-1 in 24 h R. Bruce, LHCC 2018.09.12

  11. Peak luminosity per fill • Peak performance regularly achieved in most fills • Reached record-high peak luminosity in stable beams: 2.1×1034 cm-2 s-1 • 2017: 8b4e scheme used; higher lumi reached before stable beams but leveling applied to limit pileup Data from: http://lpc.web.cern.ch R. Bruce, LHCC 2018.09.12

  12. Integrated luminosity per fill • Fills not dumped prematurely produce regularly around 0.5 fb-1in ATLAS/CMS • CMS recorded 0.79 fb-1 in one fill • Barely breaks the 2017 record of 0.77fb-1 • … while ATLAS was leveled for low-pileup run R. Bruce, LHCC 2018.09.12

  13. Fill 7127, September 5 Typical recent fill • LHCb: • separation leveling around 4.4×1032cm-2s-1 • typical production around 20 pb-1 in a fill not dumped prematurely • ALICE • separation leveling around 3.5×1030cm-2s-1 • typical production around 150 nb-1in a fill not dumped prematurely LHCb ALICE R. Bruce, LHCC 2018.09.12

  14. Van der Meer scans and β*=90 m run • Very intense period – achieved complex commissioning of two configurations interleaved with standard intensity rampup • Data collected at β*=90 m: 4.7 pb-1 for ATLAS, 6.1 pb-1for CMS • Expected that CMS got more due to asymmetric optics: β*=90 m in IR1 and βx*=90 m and βy*=45 m in IR5 90m VdM Inj Low-β R. Bruce, LHCC 2018.09.12

  15. Contents • Status and reminder from last LHCC • Operational achievements • Availability, faults and limitations • Status of luminosity production • Outlook on the rest of the year R. Bruce, LHCC 2018.09.12

  16. Overview of pp run since May • Most of the time, high-intensity fills stacked next to each other • A few longer faults MD1 + TS1 MD2 90m + vdM Rocky recovery after TS1 due to several independent issues SPS magnetreplacement PS RF issue after18 kV transformer R. Bruce, LHCC 2018.09.12

  17. Faults with longest duration • PS RF issue following 18 kV transformer failure • Several knock-on effects of transformer failure: Trip of transmission lines and injectors, PSB main power supply failed, RF problem in the PS (longest recovery) • No beam for 1.5 days, then only single bunches and later 12b trains possible • SPS dipole replacement • Magnet damaged by beam,causing vacuum leak • Replacement only possible after radiation cooldown R. Bruce, LHCC 2018.09.12

  18. Cryogenics issues • 2 compressors failed (IR6 end of June, and IR8 end of July) • Special configurations with coupling of 2 compressor stations applied, with reduced cooling capacity • Large amounts of liquid nitrogen needed: 12 t/day (IR6) and 20 t/day (IR8) – 2 trucks per day • Clogging of water cooler in IR2 and IR8 • increased He temperature injected to the refrigerator  degraded refrigeration capacity • Due to beam-induced heat load, bunch charge kept around 1.1E11 p/bunch • Plan: Interventions in TS2 • Replacement of compressors in IR6 and IR8 • Chemical cleaning of IR2 cooler • Cryogenics should go back to nominal configuration  limitation removed R. Bruce, LHCC 2018.09.12

  19. Examples of other faults • Various trips of LHC power converters • Trip of ALICE dipole • Quenches • Quenches triplet magnets • UFO in 21R3 quenched 8 magnets • Sparks at dilution kickers • Injection kickers • Issues in injectors affecting the LHC • LINAC2 bunchercavity • Electrical glitch  issue with PSB synchronization R. Bruce, LHCC 2018.09.12

  20. Beam dumps in stable beams • About half of the fills dumped by operators • Other half dumped prematurely by faults • Reducing this would increase slope of luminosity production Data from: http://lpc.web.cern.ch R. Bruce, LHCC 2018.09.12

  21. Status of 16L2, a.k.a. the Gruffalo • Very fast losses starting in cell 16L2 believed to be caused by beam interacting with macro-particles of frozen air • 4 dumps due to 16L2 since end of May, 3 in stable beams • Long time now since last event MD1 + TS1 MD2 90m + vdM R. Bruce, LHCC 2018.09.12

  22. Status of 16L2 (2) • Empirical recovery procedure seems to work well: one fill at 987 bunches for a few hours • 16L2 not a bottleneck for smooth operation with recent beams • Hard limit on beam conditions has not been probed in detail Recoveryfill Normal physics fill R. Bruce, LHCC 2018.09.12

  23. Time period before MD2: 22/6 – 22/7 LHC Availability • In period between TS1 and MD2, spent 45% in stable beams • In period after MD2 until now: Spent more than 50% in stable beams • Good result, although still room for improvement 44.9% Stable Beams 22% Operation (other) 52.8% Stable Beams 21.9% in fault 2.3% Precycle Time period after MD2: 30/7 – 7/9 Data from: https://aft.cern.ch/dashboard R. Bruce, LHCC 2018.09.12

  24. Contents • Status and reminder from last LHCC • Operational achievements • Availability, faults and limitations • Status of luminosity production • Outlook on the rest of the year R. Bruce, LHCC 2018.09.12

  25. Status of luminosity production • Surpassed 50 fb-1 in ATLAS/CMS • On average 3.5-4 fb-1 produced per week Data from: http://lpc.web.cern.ch R. Bruce, LHCC 2018.09.12

  26. Comparison with predictions (ATLAS/CMS) • On a good track for reaching 60 fb-1 target in ATLAS/CMS! Data from https://twiki.cern.ch/twiki/bin/viewauth/LhcMachine/LhcCoordinationMain R. Bruce, LHCC 2018.09.12

  27. Comparison with prediction (LHCb) • LHCb has reached the official 2018 goal of 2 fb-1 ! (although they hope for more…) Data from https://twiki.cern.ch/twiki/bin/viewauth/LhcMachine/LhcCoordinationMain R. Bruce, LHCC 2018.09.12

  28. ATLAS/CMS production over the years • 2018 production has just surpassed the production for whole 2017, and there’s still some time to go • In spite of some bumps in the road, 2018 is already another record year Data from https://twiki.cern.ch/twiki/bin/viewauth/LhcMachine/LhcCoordinationMain R. Bruce, LHCC 2018.09.12

  29. 150 fb-1 reached • Reached goal of 150 fb-1in Run 1 and Run 2 combined(~120 fb-1 in Run 2 only) • (F. Bordry, HL-LHC meeting 13/11/2017) • Good hope to reach 150 fb-1in Run 2 alone Goal: Run 1 + Run 2 Long Shutdown 1 Champagne from ATLAS R. Bruce, LHCC 2018.09.12

  30. Contents • Status and reminder from last LHCC • Operational achievements • Availability, faults and limitations • Status of luminosity production • Outlook on the rest of the year R. Bruce, LHCC 2018.09.12

  31. Outlook on rest of 2018 • Interesting period ahead • End of pp run • Special physics run: high-β* at injection • Forward physics measurements • Issues with high background under study • Heavy-ion run from beginning of November • Extra time for machine development? TS2 MD3 Today MD4 13 TeVpp physics LS2 Special run TS3 Pb-Pb ion run R. Bruce, LHCC 2018.09.12

  32. Heavy-ion run • 24 days of physics run envisaged • Completely new machine configuration • New optics through the cycle – commissioning started • Intend to switch to 75 ns bunch spacing (to be confirmed by injectors)  ~40% more bunches. Highest Pb intensity ever! • Potential to reach very high peak luminosities similar to HL-LHC leveling target • Planned to level all experiments • Plan to test 6 times design luminosities (ATLAS/CMS) • LHCb also squeezed and will be taking data • Approaching already the HL-LHC regime! • Challenges: collimation, small beam-beam separation at ALICE polarity switch R. Bruce, LHCC 2018.09.12

  33. Extra time for machine development? • In case pp physics run continues successfully: request for extra MD time from machine side • Several interesting MDs could not get time allocated yet, e.g. • Flat ATS optics as option for Run III baseline • Electron cloud effects in the inner triplets • Beam-beam long range wire compensation with flat optics for Run 3 and HL-LHC • Instabilities from coupling generated by beam-beam • Injection into the LHC with the SPS Q22 optics in TI2 for possible Run III baseline • Crystal collimation with partially stripped ions for Physics beyond Colliders • 50Hz harmonics studies for possible lifetime improvement • MD requests to be submitted following MD#3 results • Last chance to obtain MD results before long shutdown! R. Bruce, LHCC 2018.09.12

  34. Summary • Good production achieved • Established a good peak performance • On a good track to fulfill the 2018 production targets • Production in 2018 just surpassed 2017, and there’s still some time left – it is another record year • Some bumps in the road • A few longer faults and frequent premature beam aborts • Present limit on bunch charge at around 1.1E11 p/bunch from cryogenic compressor failures – mitigation planned for TS2 • 16L2 is not preventing smooth operation with present bunch intensities around 1.1E11 protons / bunch • Interesting end of 2018 ahead • End of pp physics run • High-beta run at injection under investigation • Heavy-ion run • Going into LS2 R. Bruce, LHCC 2018.09.12

  35. Additional achievement • LHC particle collisions now available for 200 CHF • Thanks for your attention! R. Bruce, LHCC 2018.09.12

  36. Backup R. Bruce, LHCC 2018.09.12

  37. Highlights from machine development • ATS optics development (achromatic telescopic squeeze) • Flat optics successfully commissioned up to 1 train (β*is 60 cm in crossing plane, 15 cm in separation plane) • Potential of higher luminosity • Compensation of beam-beam effect with DC wires • Wires integrated in tertiary collimators around CMS • Could potentially allow smaller crossing angles • Demonstrated • Crystal collimation • Beam halo channeled by bent crystals to hit deeply in absorber with little leakage • Potential for significantly improved cleaning, in particular for ions • Channeling demonstrated with newly installed crystals • Further tests planned during heavy-ion run R. Bruce, LHCC 2018.09.12

  38. Overview of faults • Considering period 31/5 – 10/9 Number of faults Average fault duration (h) R. Bruce, LHCC 2018.09.12

  39. Intensities over summer • Rather stable performance over summer • Bunch intensities stable around 1.1E11 p/bunch after intensity rampup • Not increased due to several reasons: possible risk of 16L2 dumps, cryogenics, pileup limit / start of leveling R. Bruce, LHCC 2018.09.12

  40. Heat loads Run 2, 6.5 TeV(physics fills with >800b) • Difference in heat load between sectors persists • With 25 ns beams, heat loads are now rather constant over time • Significant decrease seen with 8b4e in 2017 2016 2017 2018 8b+4e R. Bruce, LHCC 2018.09.12

  41. Evolution of arc UFO rates in 2015–2018 R. Bruce, LHCC 2018.09.12

  42. UFOs – evolution 2015 - 2018 R. Bruce, LHCC 2018.09.12

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