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LHC Beam Operations Past , Present and Future

LHC Beam Operations Past , Present and Future. Maria Kuhn on behalf of the LHC team. August 2008 First injection test. August, 2011 2.3 x 10 33 , 2.6 fb -1 1380 bunches. November 29, 2009 Beam back. 4 July, 2012 Higgs like discovery. September 10, 2008 First beams around .

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LHC Beam Operations Past , Present and Future

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  1. LHC Beam Operations Past, Present and Future Maria Kuhn on behalf of the LHC team Moriond QCD 2013

  2. August 2008 First injection test August, 2011 2.3 x 1033, 2.6 fb-1 1380 bunches November 29, 2009 Beam back 4 July, 2012 Higgs like discovery September 10, 2008 First beams around June 28 2011 1380 bunches October 14 2010 1 x 1032 248 bunches 6 June, 2012 6.8 x 1033 1380 April 2010 Squeeze to 3.5 m 2008 2009 2010 2011 2012 November 2010 Ions March 30, 2010 First collisions at 3.5 TeV September 19, 2008 Disaster Accidental release of 600 MJ stored in one sector of LHC dipole magnets 18 June, 2012 6.6 fb-1 to ATLAS & CMS LHC Timeline Moriond QCD 2013

  3. Integrated luminosity 2010-2012 Moriond QCD 2013

  4. Peak luminosity 2010-2012 2011: average 12 collisions/xing, with tails up to ~20 2012: ~30 collisions/xing at beginning of fill with tails up to ~ 40. Record peak luminosity: 7.73 x 1033cm-2s-1

  5. ALICE and LHCb (and TOTEM and ALFA) LHCb 2012:1.9 fb-1 delivered! Peak luminosities achieved in ALICE around 5 x 10 30cm-2s-1 Moriond QCD 2013

  6. Luminosity In 2012: εn = 2.5 mm e = 5.9 x 10-4mm s* = 18.8 mm (p = 4 TeV, b* = 0.6m) Moriond QCD 2013

  7. Performance from injectors 2012 N.B. the importance of 50 ns in the performance so far.This at the expense of high pile-up. Moriond QCD 2013

  8. LHC Peak Performance in 2012 Moriond QCD 2013

  9. What we have learnt so far… Moriond QCD 2013

  10. In general – beam & optics • Excellent single beam lifetime – vacuum • Excellent magnetic field quality • Beam-Beam • Head-on is not a limitation • Collective effects! • Single and coupled bunch instabilities • Better than expected aperture • b* reach established and exploited • Not trivial: small beams at the IP means large beams at the triplets! Moriond QCD 2013

  11. Operational robustness - LHC cycle • Altogether good lifetime throughout the whole LHC cycle • Machine remarkably reproducible • optics, orbit, collimator set-up, tune… Moriond QCD 2013

  12. 2012 Machine protection – the challenge met 11 magnet quenches at 450 GeV – injection kicker flash-over Beam 140 MJ Not a single beam-induced quench at 4TeV Can’t over stress the importance of this to the success of the LHC (so far). From commissioning to real confidence in under two years. R. Assmann LHC status - Kruger

  13. Availiability Moriond QCD 2013 Alick Macpherson

  14. Machine performing well, huge amount of experience & understanding gained. Good system performance, excellent tools, reasonable availability following targeted consolidation. This is the legacy for post LS1 Moriond QCD 2013

  15. LS1 Moriond QCD 2013

  16. Moriond QCD 2013

  17. LHC MB circuit splice consolidation proposal Phase II Application of clamp and bus bar insulation Phase III Insulation between bus bar and to ground, Lorentz force clamping Phase I Installation of new shunts Moriond QCD 2013

  18. Possible Limitations For Post LS1 Moriond QCD 2013

  19. 25 ns & electron cloud • Photoelectrons from synchrotron radiation accelerated by the proton beam • Electrons bounce into chamber wall → secondary electrons are emitted • Due to short bunch spacing, high bunch intensity and low emittance: electron cloud build-up! Moriond QCD 2013

  20. Electron cloud: possible consequences • single-bunch instability • multi-bunch instability • emittance growth • gas desorption from chamber walls • heat load • particle losses, interference with diagnostics,… Electron bombardment of a surface has been proven to reduce drastically the secondary electron yield (SEY) of a material. This technique, known as scrubbing, provides a mean to suppress electron cloud build-up and its undesired effects Moriond QCD 2013

  21. 25 ns & electron cloud The SEY evolution significantly slows down during the last scrubbing fills (more than expected from simulations and lab. experiments) • Downside: scrubbing takes time (several weeks!) • Electron cloud free environment after scrubbing at 450 GeV seem not be reachable in acceptable time. • Post LS1 operation with high heat load and electron cloud density seems to be unavoidable. End of 2012 tests Giovanni Iadarola and team - Evian 12 • Reconstructed comparing heat load meas. and PyECLOUD sims. Moriond QCD 2013

  22. UFOs • UFOs: showstopper for 25 ns and 6.5 TeV? • 10x increase and harder UFOs • (but no increase in low intensity fills) • UFO “scrubbing”: does it work? • Deconditioning expected after LS1 • Post LS1 operation: start with lower energy and/or 50 ns Tobias Baer Moriond QCD 2013

  23. Operational scenarios After LS1 Moriond QCD 2013

  24. Beam from injectors LS1 to LS2 BCMS = Batch Compression and (bunch) Merging and (bunch) Splittings Batch compression & triple splitting in PS RendeSteerenberg, Gianluigi Arduini, TheodorosArgyropoulos, HannesBartosik, Thomas Bohl, KarelCornelis, HeikoDamerau, Alan Findlay, Roland Garoby, Brennan Goddard, Simone Gilardoni, Steve Hancock, Klaus Hanke, Wolfgang Höfle, Giovanni Iadarola, Elias Metral, Bettina Mikulec, YannisPapaphilippou, Giovanni Rumolo, Elena Shaposhnikova,…

  25. 50 ns versus 25 ns Expect to move to 25 ns because of pile up… Moriond QCD 2013

  26. b* & crossing angle • b* reach depends on: • available aperture • collimator settings • required crossing angle which in turn depends on • emittance • bunch spacing Moriond QCD 2013

  27. Potential performance • All values at 6.5 TeV collision energy • 1.1 ns bunch length • 150 days proton physics • 85 mbcross-section • * different operational model – caveat - unproven All numbers approximate

  28. Potential performance – in words • Nominal 25 ns • gives more-or-less nominal luminosity (1.0 x 1034 cm-2s-1) • BCMS 25 ns • gives a healthy 1.7 x 1034 cm-2s-1 • peak <m> around 50 • 83% nominal intensity • Nominal 50 ns • gives a virtual luminosity of 1.6 x 1034 cm-2s-1 with a pile-up of 87 • levelling mandatory • BCMS 50 ns • gives a virtual luminosity of 2.3 x 1034 cm-2s-1 with a pile-up of 138 • levellingeven more mandatory Moriond QCD 2013

  29. 2015 strategy – for discussion LHC Operation

  30. Conclusions • Availability better than might have been expected. • Machine now magnetically, optically, operationally well understood • System performance • generally good to excellent • issues identified and being addressed • Limitations well studied, well understood and quantified • still some potential implications for post LS1 operation • Restart post LS1 with 50 ns • before moving to 25 ns • non electron cloud free environment to be accepted at least initially Moriond QCD 2013

  31. BACKUP LHC Operation

  32. Post LS1 energy • Our best estimates to train the LHC (with large errors) •  30 quenches to reach 6.25 TeV •  100 quenches to reach 6.5 TeV • Two quenches/day  2 to 5 days of training per sector • The plan • Try to reach 6.5 TeV in four sectors in March 2014 • Based on that experience, we decide if to go at 6.5 TeV or step back to 6.25 TeV in March 2014 EzioTodesco – Chamonix 12 Moriond QCD 2013

  33. 2015 strategy – more detailed • Low intensity commissioning of full cycle – 2 months • First stable beams – low luminosity • Intensity ramp-up – 1 to 2 months • 50 ns operation (at pile-up limit) • Characterize vacuum, heat load, electron cloud, losses, instabilities, UFOs, impedance • Options thereafter: • 1 week scrubbing for 25 ns, say 1 week to get 25 ns operational (if b* and crossing angles are changed), intensity ramp up with 25 ns with further scrubbing required • Commission levelling of 50 ns and push bunch intensity up, emittance down… not at all favored by experiments! Moriond QCD 2013

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