FGC Software Design Review

LHC status120-6-2011

The Large Hadron ColliderMike Lamontfor the LHC teamIntroductionPerformance in 2010Progress in 2011Looking ahead ConclusionsOverview20-6-20112LHC status

CERNs injector complexLHC status320-6-2011

LHC layout and accelerator systemsLHC status420-6-2011

Luminosity - reminderLHC status520-6-2011

NNumber of particles per bunchKbNumber of bunchesfRevolution frequencyBeam size at interaction pointFReduction factor due to crossing angleEmittance area in phase space occupied by beamEnergy normalized emittanceBeta function at IP defines beam envelope

Lay the foundations for 2011 and the delivery of 1 fb-1. Peak luminosity target 1x1032 cm-2s-1Gain solid operational experience of injecting, ramping, squeezing and establishing stable beamsSteady running at or around 1 MJ for an extended period Perform a safe, phased increase in intensity up to around 30 MJ per beam2010 main aimsLHC status620-6-2011

2010 parametersLHC status2010NominalEnergy [TeV]3.57 beta* [m]3.5, 3.5, 3.5, 3.5 m0.55, 10, 0.55, 10Emittance [mm.mrad]2.0 3.5 start of fill3.75 Transverse beam size at IP [microns]~6016.7 Bunch intensity1.2e111.15e11Number of bunches368348 collisions/IP2808Stored energy [MJ]28360Peak luminosity[cm-2s-1]2e321e34720-6-2011Luminosity: 3 running periods8

Bunch trainsNominal bunch commissioningInitial luminosity runNominal bunch operation(up to 48)Performance ramp-up(368 bunches)Performance ramp-up made possible by a safe, staged commissioning.Meticulous preparation for unsafe beams!20-6-2011LHC statusLuminosity 2010LHC status920-6-2011

CMSStatus LHC Stored Energy80 kg TNT

Stored energy reached at 3.5 TeV: 28.0 MJ10LHC statusRalph Assmann20-6-2011Excellent single beam before collisions - over 300 hours

Luminosity lifetime 15- 20 hours, better in 2011Reasonably well given by emittance growth and intensity decayMinimal drifts in overlap beams very stable

Intensity lifetime ~90 hoursLuminosity burn, losses on collimators

Emittance growth (hor. ~ 30 hours, vert. ~ 20 to 40 hours)Intra Beam Scatteringand something else at least sometimes the hump

Lifetimes1120-6-2011LHC statusAperture looks goodLHC status12

20-6-2011Optics & magnetic machineOptics stunningly stable

Machine magnetically and optically well understoodExcellent agreement with model and machineMagnetically reproducibleImportant because set-up remains valid from fill to fillLHC status1320-6-2011Measured Cleaning at 3.5 TeV

IR8IR1IR2IR5Momentum CleaningDump Protection Col.(beam1, vertical beam loss, intermediate settings)LHC statusMaking sure the hierarchy is respected1420-6-2011Beam cleaning efficiencies 99.98% ~ as designedExcellent single beam lifetimeRamp & squeeze essentially without lossNo quenches with beam above 450 GeVExcellent performance of Machine ProtectionOptics close to model (and correctable)Excellent reproducibilityAperture as expectedBetter than nominal from injectorsEmittances, bunch intensityBeam-beam: can collide nominal bunch currentsWith smaller that nominal emittances surprise!

LHC 2010 - summary15And surprisingly good availability 20-6-2011LHC statusOverall LHC efficiency in 201016

W. Venturini65%availabilityNot bad for the first year of operation!20-6-2011LHC statusVery fast commissioning plan worked:Collisions within 50 hours of first injectionProfited of the experience of the proton runStable beams within 4 days ( and physics)Rapid progression in number of bunches

The LHC worked with Pb beamsNo rapidly decaying, invisible beams No quenchesSome new losses and radiation problemsPb run 201020-6-201117LHC status

Integrated Luminosity10 mb-1Peak Stable Luminosity Delivered3.04x1025 cm-2s-1Maximum number of bunches in collision137Average bunch population1.2x108 ions (>60% above nominal)Pb run 2010 - Achievements

06/06/201118

7x10^7 ions is the nominal population18

Pb run 2010: CollimationGenerally according to predictions (i.e. efficiency is a factor 100-500 worse than p).J. Jowett 20-6-201119LHC status

PROBLEMS TWO OF themLHC status2020-6-2011Many sudden local losses have been recorded. No quench, but preventive dumpsRise time around of the order 1 ms.Potential explanation: dust particles falling into beam creating scatter losses and showers propagating downstreamDistributed around the ring arcs, inner triplets, IRs

UFOs unidentified falling objectsLHC status

2120-6-2011

Electron cloudLHC statusSchematic of electron cloud build up in LHC arc beam pipe due to photoemission and secondary emission [F. Ruggiero] ReflectionSecondary emission yield [SEY]2220-6-2011Vacuum pressure rise (background in experiments)Single-bunch instabilityMulti-bunch instabilityIncoherent emittance growthHeat load in cold arcs (quenches in the limit)Vacuum activity started off in regions with common beam pipe at 450 GeV as we pushed up the number of bunches with 150 ns spacingTest solenoids cured problem electron cloudTried 50 ns bunch spacingThings really kicked offHigh vacuum activity in warm regions Significant heat load in cold regionsInstabilities and beam size growth observedSurface conditioning (scrubbing) observedGas desorption rates and SEY dropTime constant < 1 daySituation a lot cleaner with 75 nsincoherent effects seen emittance blow-up800+ bunches injected into both beams

Experience in 2010LHC status2320-6-20112010 observations are certainly due to ~ 2 < SEY < 2.5, whereas 1.7 was usually the max value studied in the past

Scrubbing with large emittance, high intensity 50 ns beam

Time around 10 days including preparation and validation

Lots of wire wrapped around warm bits during the technical stop (solenoids)

Scrubbing strategy for 201124LHC status20-6-2011Solenoids between DFBX and D1 in IR1R LHC status

2520-6-2011Motivation is clear!

1 fb-1 delivered to each of IP1, IP5 and IP8 at 3.5 TeVChallenge to deliver 1 fb-1 to IP8Maximum luminosity : from 2e32 to 3e32 cm-2 s-1Luminosity leveling via separation required to get closeAlicepp run: 5e29 < L < 5e30 cm-2 s-1, < 0.052011: main goals2620-6-2011LHC status

fast, secure and far-reachingDecided on beta* = 1.5 m in Atlas, CMS; 3 m in LHCb; 10 m in AliceBeam commissioning: 3 weeksExit - stable beams with low number of bunchesRamp-up to ~200 bunches (75 ns): 2 weeksMulti-bunch injection commissioning continuedStable beams Technical Stop: 4+1 daysScrubbing run: 10 days including 50 ns injection comm. Intermediate energy run 5 daysResume 75 ns operation and increase no. bunches: 3 weeks300 400 600 800 930 - MPS and OP qualification Physics operation 75 ns: ~930 bunches50 ns remains an option if things look goodBaseline scenario for 2011 2720-6-2011LHC statusWe are here!2011 LHC schedule Q1/Q228LHC status20-6-2011

2011 recommissioningLHC status2919th FebruaryFirst beam, circulating beams established.3rd MarchFirst collisions at 3.5 TeV, beta*=1.5 m with pilot beams5th MarchNominal bunches at 3.5 TeV, start collimator set-up, injection and beam dump set-up & validation13th MarchFirst stable beams, 3 bunches per beam, initial luminosity 1.6e30 cm-2s-118th March32 bunches per beam, initial luminosity ~3e31 cm-2s-119th March64 bunches per beam, initial luminosity ~6e31 cm-2s-120th March1.45e32 cm-2s-1 with 75 nsFast re-commissioning, improvements across the board.Operation cycle now well optimized: faster ramp & squeeze, much fewer manual actions required by shift crews20-6-2011Machine still beautifulBeta beating corrected down to 5-10%!!Confirmed stability of the opticsFinal b* values from K-modulation:

Errors around 4-10%Aperture: global > 12 s, triplet > 14.5 s

Beam/planeIR5IR1B1H1.501.53B2H1.481.57B1V1.521.50B2V1.521.5720-6-201130LHC statusScrubbing runImpressive progression in spite of several technical problems not related to the scrubbing (> 3 days lost).

5 days of scrubbing

All solenoid off (experiments and vacuum solenoids at warm sections)

DateBunches B1+B2Tue 5th April300+300Wed 6th April 408+336Sat 8th April588+588Sun 9th April804+804Mon 10th April1020+1020Careful increase in intensity (in steps of 200 bunches) monitoring cryogenics, vacuum, machine protection and particularly RF

Limited to 72 bunches/train by injection performance

Reached 1020 bunches per beam at the end of the scrubbing run more than 1014 protons per ring

20-6-201131LHC status31Scrubbing: effect on beamStarted like this 300 bunches20-6-201132LHC status

804 bunches some hours of scrubbingScrubbing: Heat-loads in the arcs

Impressive reduction of the heat load in few hours: results consistent with SEY reduction from 2.5 to 1 MJ down the linesHigh temperature superconducting current lead quenched (7th April) Invoked quench of 11 magnetsInjection Kicker Flashover (18th April)Not pretty, heavy beam loss

Increasing intensity machine protection20-6-201138LHC statusHoweverLuminosity lifetime > 20 hoursLifetimes during a fill (1092 bunches)

Very good lifetime during the whole processHardly visible when we go in collision

c/o ATLAS20-6-201139LHC statusIP8 Luminosity leveling operational

20-6-2011LHC status40

Needed to get to 1 fb-1 in LHCb given the limit in peak luminosity40LHC precision frontLHC status4120-6-2011

VdM scanIP1 HIP1 V absolute luminosity normalization low, well understood backgrounds precision optics for ATLAS-ALFA and TOTEMprecise measurement of the luminous region +beam intensity --> absolute luminosity and cross section calibration currently ~ 5 % level,41

And weve been producing some luminosityLHC status4220-6-2011Luminosity 1.2-1.3 x1033cm-2s-1Back to back fills with 1092 bunches42Peak LuminosityLHC status20-6-201143

43

20-6-2011LHC status44WeeklyLHC status20-6-2011

4545LHCbLHC status4620-6-2011

Integrated Luminosity to date (IR1-5/IR8)1.06 fb-1/0.36 fb-1Peak Stable Luminosity Delivered1.26x1033 cm-2s-1Maximum number of bunches at 450 GeV/c1308Maximum number of bunches in collision1092Maximum intensity in collision1.3x1014 p/beamMaximum stored energy73 MJ/beamAverage bunch population1.2x1011 pEmittance in collision~2.5 mmMaximum Luminosity Delivered in one day56 pb-1Maximum Luminosity Delivered in one week239 pb-1Status20-6-201147LHC statusWeek 23 the week before last! LHC status20-6-2011DateFill numberTime in stable beamsInt. lumi [pb-1]Cause of dumpMon 6th 18549m.59trip of RQ6.L2 Mon-Tues 185514h21m41.3RTQX2.R1 - FGCTue-Wed185610h50m31.0Alice dipole tripWed18580Big UFO IP2Wed-Thu18593h56m13.4Electrical glitchThu186211h12m32.4Trip RSQSX 400 V PSThu - Sat18639h4330.8PLC DFB-cryo MS L1Sat - Sun18646h4823.1D2.L1 bus bar quenchSun - Mon186513h36m42.6Collimator controlsMon186620m1.3RF Total Voltage Intlk B1 Mon 14th18678h14m28.8RF module trip4848Week 23LHC status20-6-2011

4949Week 23LHC status20-6-2011

5050It is not always easy! A day in June.

LHC status20-6-2011Collimator temperatureRF arcQPS noise quenchUFO IR2Cryo S56Cryo S34Injection preparation for 144b51And lets not mention last week.51Outlook for 2011 (protons)110 more days at >1033 cm-2s-1 and an efficiency for physics (Hubner factor) of 0.2 gives another 2 to 3 fb-1Main known unknowns: UFOs and SEU20-6-2011LHC status52

25 ns studies to come during MDs (to sort out injection and beam stability issues) and possibly an operational development period to validate scrubbing and future operation

Outlook for 2011 (Pb)Number of bunches vs. bunch populationPossibility to reach 540 bunches but likely limited to nominal bunch population

OpticsTake over ATLAS and CMS * from protonsSqueeze ALICE to same value *= 1.5 m - 2 days setup

Could reach peak luminosities in the range of 1 to 1.41026 cm-2s-1 and integrate 30 to 50 mb-1

Short run more sensitive to any prolonged machine problems

20-6-201153LHC status

Testing p-Pb in 2011Important to resolve uncertainties regarding feasibility, Pb intensity limit from unequal revolution frequencies at injection, rampModulation of long-range beam-beam, transverse feedback, tune-control

Crucial questions are related to injection and rampingEffects of protons (say 10% of nominal) on one Pb bunch Inject few Pb bunches against some convenient p filling scheme Possible in 2011 (OK in 2012)Detailed planning of MD being worked out

20-6-201154LHC statusPhysics data-taking until end of 2012Following measurements of the copper stabilizers resistances during the Christmas stop, we will re-evaluate the maximum energy for 2012 (Chamonix 2012)Baseline is probably 50 nsBetter emittances from injectors with potential to push lower, better performance for a given total beam intensityPossible to push up bunch intensityBut first see what 25 ns brings

201220-6-201155LHC statusGiven up making predictions of integrated luminosity!The LHC is a beautiful machine (although some times temperamental) a real testament to those that built it.High intensity was known to require more careful control of the machine parameters and to potentially bring a host of other issues into playWork very much in progress50 ns has proven to be a good choice - more potential> 1 fb-1 delivered to ATLAS and CMS ~0.36 fb-1 delivered to LHCb How much higher in peak luminosity we can go for ATLAS and CMS will depend on extent of UFOs, SEUs etc.Aiming for 1380 bunches

Conclusions20-6-201156LHC status