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LHC beam operation past , present, future

LHC beam operation past , present, future. Mike Lamont for the LHC team. 2011 – recap. 75 ns. 50 ns. Squeeze further. Increase number of bunches. Increase bunch intensity . Scrubbing. Reduce beam size from injectors. Initial commissioning. Starting out .

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LHC beam operation past , present, future

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  1. LHC beam operationpast, present, future Mike Lamontfor the LHC team

  2. 2011 – recap 75 ns 50 ns Squeeze further Increase number of bunches Increase bunch intensity Scrubbing Reduce beam size from injectors Initial commissioning LHC status

  3. Starting out • Efficient commissioningleading into 75 ns operation • Intermediate energy run • Scrubbing rocky but successful • Dynamic effects: synchrotron radiation, e-cloud  Scrubbing  reduction of the LHC pressure Decision: go with 50 ns LHC status

  4. Number of bunches++ • End April: “fabulous performance” • A little bit of caution – extended period at 1092 bunches • Pushing 1.3e11 ppb but high beam intensity issues starting to show 1033 • Blow-up of some bunches at injection • E-cloud solenoids, triplet vacuum, beam screen cooling • 108 b injection sort of OK, worry about scraping in the SPS • Injection kicker heating, vacuum kicking off in IR8 • RF arc detectors – false dumps • Abort gap population • SEUs starting to show • Collimator heating LHC status

  5. LHC machine breaks 3 new world records at 10h41 Sunday 29 May: 2 x 1092 bunches colliding, luminosity above 1.2 x 10^33, and a beam energy of 73 MJ. LHC status

  6. Looking towards 1380 bunches • Strong emittance blow-up at injection • Chromaticity stability, persistent currentdecay compensation • Eventually suppressed by octupoles at 450 GeV • Bunch length control in ramp • Satellite collisions tested • RF versus intensity versus trips – worrying about couplers – dump on cavity trip deployed • Vacuum at 2&8 - instabilities • Instrumentation issues • UFO storms • High losses at collimators • 1 SEU dump per day • Trim quad circuits tripping during squeeze 15thJune: 1 fb-1 LHC status

  7. Summer - now what do we do? • July: starting to look encouraging… • August: getting so worried about SEUs we had a brainstorming • and a mini-Chamonix • Decision to push: • beam from the injectors • squeeze LHC status

  8. Beam from injectors Excellent performance – years in the preparation • Best in 2011 with 50 ns: • ~1.45 x 1011 ppb • ~2.3 microns into collision • Design with 25 ns: • 1.15 x 1011 ppb • Normalized emittance 3.75 microns LHC status

  9. IR1 and IR5 aperture at 3.5 TeV 2011’s “platinum mine” We got 4-6 sigmas more than the expected 14 sigma Triplet aperture compatible with a well-aligned machine, a well centred orbit and a ~ design mechanical aperture (small tolerance) ~3 cm ~600 m Stefano Redaelli LHC status

  10. Squeeze • Beta* = 1 m – big success – 3.3e33 cm-2s-1 • Pushing bunch intensities to 1.35e11 • Collimator interlocks, PADs/MADs, injection quality, vacuum, collimator heating, Alice background, b2 instability, RF de-bunching, tune feedback in squeeze LHC status

  11. Impressive final run in MirkoPojer LHC status

  12. Very positive ending Ion man LHC status

  13. 2011 • Another remarkable year • It was nearly always a battle… • Remarkably no real show stoppers • Successfully took on: • Total intensity • Bunch spacing • Bunch intensity • Emittance • Beta* & aperture LHC status

  14. Of note • Operational robustness • Precycle, injection, 450 GeV, ramp & squeeze & collisions • Machine protection • Unpinned by superb performance of machine protection and associated systems • Rigorous machine protection follow-up, qualification and monitoring (Post Mortem analysis, MPP, rMPP) • Routine collimation of 110 MJ LHC beams without a single quench from stored beams. LHC status

  15. Operation efficiency • Overall efficiency • Pretty good considering that this is the LHC • Overall time in stable beams 34% • Premature dumps • 50% of all STABLE BEAMS fills lasted less than 3 hours 34% LHC status

  16. Radiation to electronics (R2E) • xMas-Mitigation crucial: patch, shielding, relocat. • Patches to continue during 2012 • Particular emphasis (analysis) of ‘new’ failures LHC status

  17. Concerted program of investigations, simulations, tests with beam … Tobias Baer LHC status

  18. Vacuum • Unexpected pressure rise (10-6 mbar) observed in LSS2-LSS8 (D1) and close to CMS: bad RF contact (x-rays inspection) interventions done in 2 & 8 & CMS to resolve RF finger issues - shouldn't be a problem in 2012. CMS LSS2 LHC status

  19. TDI – beam screen heating LHC status

  20. 2011 to 2012 • Well organized, productive Xmas technical stop • Lot of R2E related work • Plus consolidation and improvements of many systems • Vacuumconsolidation to address successfully diagnosed causes of instabilities in 2011 • Injection collimators issues diagnosed and understood - spare in preparation - fingers crossed in the meantime • Cool-down of machine exactly on schedule - cryogenics demonstrating full mastery… • Very smooth hardware commissioning including careful quench-less commissioning of main circuits to 4 TeV • Machine checkout proceeding well - good for beam next Tuesday afternoon LHC status

  21. 2012 strategy 4 TeV β*=0.6m→0.7m→0.9m 50 ns ∫Ldt = 5 fb-1 in June? Dumps=30-50 ∫Ldt = 15-19 fb-1 Pile-Up=26-35 LHCb ∫Ldt=1.5 fb-1 Lpeak=5-6.8 1033 cm-2s-1 TCP gap=2.2mm IP1 β*=500m SPS ε= 2 μm SPS Np= 1.6 1011 p-Pb: 3.5 TeV or 4 TeV • ∫Ldt = 15- 23 nb-1 β*=(0.6,0.6,0.6,3)m LHC status Rogelio Tomas

  22. Collimator settings 2012 Collimation hierarchy has to be respected in order to achieve satisfactory protection and cleaning 2012: tight settings LHC status

  23. How tight? Norway Iberian peninsula Intermediate settings (2011): ~3.1 mm gap atprimary collimator Tight settings: ~2.2 mm gap atprimary collimator LHC status

  24. 2012 run configuration • Energy – 4 TeV • Low number of quenches (as in 2011) assumed • Bunch spacing - 50 ns • Collimator settings – tight • As discussed – NB not yet proven operationally • Atlas and CMS beta* - 60 cm • with 70 cm and 90 cm as fallbacks • Alice and LHCb beta* - 3 m • Natural satellites versus main bunches in Alice LHC status

  25. Bunch spacing Performance from injectors LHC status

  26. 2012 LHC schedule Q1/Q2 1 2 3 4 LHC status

  27. 2012 LHC schedule Q3/Q4 6 5 High beta* runs for ALFA and TOTEM Van der Meer scans LHC status

  28. 2012 - breakdown ~150 days LHC status

  29. 50 ns performance estimate 4 TeV, 50 ns, 1380 bunches, 1.6e11, 2.5 microns150 days of proton physics (assuming similar efficiencies to 2011) LHC status

  30. 25 ns performance estimate 4 TeV, 25ns, 1380 bunches, 1.6e11, 2.5 microns140 days of proton physics (extra scrubbing required) Conclusion: 25 ns not competitive with 50 ns LHC status

  31. LHC status

  32. Conclusions • Good performance in 2011 from working on all available parameters • Very definitely exploring the effects of high intensity beams • SEUs, beam induced heating, vacuum instabilities… • Operational efficiency suffering as a result • Main gain in 2012 is use of tight collimator settings and reduced beta* • 5 to 6 x 1033 cm-2s-1 and 15 fb-1 should be possible • Hope for improved operational efficiency • R2E mitigation measures • but partially countered by increased peak performance • Another long, interesting year in prospect… LHC status

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