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

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

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

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 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

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

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

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

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

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) LHC status Stefano Redaelli 11/3/2012 ~600 m ~3 cm

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

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

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

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

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

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

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

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

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.

TDI – beam screen heating 11/3/2012 LHC status

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

2012 strategy 4 TeV 50 ns p-Pb: 3.5 TeV or 4 TeV β*=0.6m→0.7m→0.9m ∫Ldt = fb -1 L peak = cm -2 s -1 SPS N p = SPS ε= 2 μm Pile-Up=26-35 ∫Ldt = 5 fb -1 in June? β*=(0.6,0.6,0.6,3)m TCP gap=2.2mm LHCb ∫Ldt=1.5 fb -1 IP1 β*=500m Dumps=30-50 nb -1 ∫Ldt = nb -1 11/3/2012 LHC status Rogelio Tomas

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

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

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

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

2012 LHC schedule Q1/Q /3/2012 LHC status

2012 LHC schedule Q3/Q /3/2012 LHC status High beta* runs for ALFA and TOTEM Van der Meer scans

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

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 90Intermediate5.1e – Tight6.2e – % 60Tight6.8e – % 11/3/2012 LHC status

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 80Tight3.8e /3/2012 LHC status Conclusion: 25 ns not competitive with 50 ns

11/3/2012 LHC status

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 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