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LHC beam operation past, present, future Mike Lamont for the LHC team

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75 ns50 ns 2011 recap Increase number of bunches Reduce beam size from injectors Squeeze further Increase bunch intensity Initial commissioning Initial commissioning Scrubbing 11/3/2012 LHC status

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Starting out Efficient commissioning leading 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 11/3/2012 LHC status

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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 10 33 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 IR 8 RF arc detectors false dumps Abort gap population SEUs starting to show Collimator heating 11/3/2012 LHC status

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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. 11/3/2012 LHC status

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Strong emittance blow-up at injection Chromaticity stability, persistent current decay 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 Looking towards 1380 bunches 15 th June: 1 fb -1 11/3/2012 LHC status

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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 11/3/2012 LHC status Decision to push: beam from the injectors squeeze

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Beam from injectors 11/3/2012 LHC status Excellent performance years in the preparation Best in 2011 with 50 ns: ~1.45 x 10 11 ppb ~2.3 microns into collision Design with 25 ns: 1.15 x 10 11 ppb Normalized emittance 3.75 microns

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IR1 and IR5 aperture at 3.5 TeV 2011s 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) LHC status Stefano Redaelli 11/3/2012 ~600 m ~3 cm

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Squeeze Beta* = 1 m big success 3.3e33 cm -2 s -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 11/3/2012 LHC status

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Impressive final run in Mirko Pojer 11/3/2012 LHC status

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Very positive ending Ion man 11/3/2012 LHC status

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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 11/3/2012 LHC status

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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. 11/3/2012 LHC status

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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% 11/3/2012 LHC status

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Radiation to electronics (R2E) xMas-Mitigation crucial: patch, shielding, relocat. Patches to continue during 2012 Particular emphasis (analysis) of new failures 11/3/2012 LHC status

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11/3/2012 LHC status Concerted program of investigations, simulations, tests with beam Tobias Baer

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Vacuum 11/3/2012 LHC status LSS2 CMS 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.

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TDI beam screen heating 11/3/2012 LHC status

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2011 to 2012 Well organized, productive Xmas technical stop Lot of R2E related work Plus consolidation and improvements of many systems Vacuum consolidation 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 11/3/2012 LHC status

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2012 strategy 4 TeV 50 ns p-Pb: 3.5 TeV or 4 TeV *=0.6m0.7m0.9m Ldt = 15-19 fb -1 L peak =5-6.8 10 33 cm -2 s -1 SPS N p = 1.6 10 11 SPS = 2 m Pile-Up=26-35 Ldt = 5 fb -1 in June? *=(0.6,0.6,0.6,3)m TCP gap=2.2mm LHCb Ldt=1.5 fb -1 IP1 *=500m Dumps=30-50 nb -1 Ldt = 15- 23 nb -1 11/3/2012 LHC status Rogelio Tomas

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Collimator settings 2012 Collimation hierarchy has to be respected in order to achieve satisfactory protection and cleaning 11/3/2012 TCP 74.3 TCSG 76.3 TCLA 78.3 TCSG 67.1 TCDQ 67.6 TCT9.0 Aperture10.5 2012: tight settings LHC status

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How tight? 11/3/2012 Intermediate settings (2011): ~3.1 mm gap at primary collimator Tight settings: ~2.2 mm gap at primary collimator Norway Iberian peninsula LHC status

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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 11/3/2012 LHC status

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Bunch spacing Performance from injectors Bunch spacing From Booster Protons per bunch (ppb) Emittance H&V [mm.mrad] 150 Single batch 1.1 x 10 11 1.6 75 Single batch 1.2 x 10 11 2.0 50 Single batch 1.45 x 10 11 3.5 50 Double batch 1.6 x 10 11 2.0 25 Double batch 1.2 x 10 11 2.7 11/3/2012 LHC status

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2012 LHC schedule Q1/Q2 1 1 4 4 3 3 2 2 11/3/2012 LHC status

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2012 LHC schedule Q3/Q4 5 5 6 6 11/3/2012 LHC status High beta* runs for ALFA and TOTEM Van der Meer scans

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2012 - breakdown 11/3/2012 LHC status Days Machine check-out2 Commissioning with beam21 Machine development22 Technical stops20 Scrubbing (25 ns)3 Technical stop recovery6 Initial intensity ramp-up~21 Proton running~126 Special runs~8 Ion setup4 Ion run24 ~150 days

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50 ns performance estimate 4 TeV, 50 ns, 1380 bunches, 1.6e11, 2.5 microns 150 days of proton physics (assuming similar efficiencies to 2011) Beta* [cm] CollimatorsPeak Lumi [cm- 2 s -1 ] Int. Lumi [fb -1 ] Pile-upIncrease in peak 90Intermediate5.1e3312.1 14.526 70Tight6.2e3314.7 17.631+22% 60Tight6.8e3316.2 19.335+10% 11/3/2012 LHC status

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25 ns performance estimate 4 TeV, 25 ns, 1380 bunches, 1.6e11, 2.5 microns 140 days of proton physics (extra scrubbing required) Beta* [cm] CollimatorsPeak Lumi [cm- 2 s -1 ] Int. Lumi [fb -1 ] Pile-up 80Tight3.8e338.310 11/3/2012 LHC status Conclusion: 25 ns not competitive with 50 ns

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11/3/2012 LHC status

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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 10 33 cm -2 s -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 11/3/2012 LHC status