initial operation & requirements on the machine

R.Bailey, LHCMAC, June 2005R.Bailey, LHCMAC, June 2005

Initial OperationInitial Operation&&

Requirements on the MachineRequirements on the Machine

R. BaileyR. Bailey

AB LHC OperationsAB LHC Operations

R,Bailey, LHCMAC, June 2005R,Bailey, LHCMAC, June 2005

Global requirements on the machineGlobal requirements on the machine

Highest energy proton collisions for ATLAS and CMSHighest energy proton collisions for ATLAS and CMS Nominal luminosity 10Nominal luminosity 103434 cm cm-2-2 s s-1-1 in points 1 and 5 in points 1 and 5

Highest energy proton collisions for LHCbHighest energy proton collisions for LHCb Nominal luminosity ~ 5 10Nominal luminosity ~ 5 103232 cm cm-2-2 s s-1-1 in point 8 in point 8

Proton collisions @ various energies for ALICEProton collisions @ various energies for ALICE Nominal luminosity ~ 10Nominal luminosity ~ 103030 cm cm-2-2 s s-1-1 in point 2 in point 2

Ion collisions @ various energies for ALICEIon collisions @ various energies for ALICE Nominal luminosity ~ 10Nominal luminosity ~ 102727 cm cm-2-2 s s-1-1 in point 2 in point 2 ATLAS and CMS will also take dataATLAS and CMS will also take data

Proton collisions @ various energies for TOTEMProton collisions @ various energies for TOTEM

Proton luminosity

running

Dedicated

Dedicated


Lower energy runsLower energy runs

TOTEM would like to have low energy runs during the first TOTEM would like to have low energy runs during the first phase of the LHC operation:phase of the LHC operation:

√√s= 1.8 TeV for direct comparison with TEVATRON s= 1.8 TeV for direct comparison with TEVATRON √√s ~ 8 TeV to measure s ~ 8 TeV to measure

ALICE would like to have a dedicated pp run at √s= 5.5 TeV ALICE would like to have a dedicated pp run at √s= 5.5 TeV (nucleon-nucleon √s for nominal Pb-Pb runs) for a direct (nucleon-nucleon √s for nominal Pb-Pb runs) for a direct comparison of the Pb-Pb and pp data. A lower energy Pb-Pb comparison of the Pb-Pb and pp data. A lower energy Pb-Pb run may be requested too. However both requests are for a run may be requested too. However both requests are for a later stage of the LHC operationlater stage of the LHC operation

Lower energy pp runs during early running are also discussedLower energy pp runs during early running are also discussed

Low energy runs are currently neither in the ATLAS nor in the Low energy runs are currently neither in the ATLAS nor in the CMS baseline physics program. However this request may CMS baseline physics program. However this request may come at a much later phase of the LHC operationcome at a much later phase of the LHC operation

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Proton luminosity runningProton luminosity running

HHSM SM -> 4 l (M -> 4 l (MHiggs Higgs = 140-155 GeV and 190-450 GeV) can be discovered with = 140-155 GeV and 190-450 GeV) can be discovered with ~ 4 fb~ 4 fb-1 -1

Some supersymmetry can be discovered at more modest luminosities ~ 1 fbSome supersymmetry can be discovered at more modest luminosities ~ 1 fb -1-1

Potential for b-physics right from startupPotential for b-physics right from startup

ATLAS and CMSATLAS and CMS Minimize event pileup early onMinimize event pileup early on Go to 25ns as soon as possibleGo to 25ns as soon as possible Will make use of any beam for detector commissioningWill make use of any beam for detector commissioning

LHCbLHCb Tune IP8 to optimize luminosity (1m < Tune IP8 to optimize luminosity (1m < ** >> 50m)50m) Go to 25ns as soon as possible (optimized for ~ 1 events/crossing)Go to 25ns as soon as possible (optimized for ~ 1 events/crossing) Dipole polarity change ~ every fillDipole polarity change ~ every fill

ALICEALICE Will use proton beams (intrinsic interest and reference data)Will use proton beams (intrinsic interest and reference data) Tune IP2 to optimize luminosity (0.5m < Tune IP2 to optimize luminosity (0.5m < ** >> 50m)50m) Magnet polarities change ( + - 0 ) a few times per yearMagnet polarities change ( + - 0 ) a few times per year

(106 seconds @ <L> of 1033 cm-2 s-1 = 1 fb-1)



High luminosity runningHigh luminosity running

Eventual goal: luminosity of 10Eventual goal: luminosity of 103434 cm cm-2-2 s s-1 -1 (ATLAS & CMS) (ATLAS & CMS)

Nominal ParametersNominal Parameters

Beam energy (TeV)Beam energy (TeV) 7.07.0

Number of particles per bunchNumber of particles per bunch 1.15 101.15 101111

Number of bunches per beamNumber of bunches per beam 28082808

Crossing angle (Crossing angle (rad)rad) 285285

Nomalised transverse emittance (Nomalised transverse emittance (m rad)m rad) 3.753.75

Bunch length (cm)Bunch length (cm) 7.557.55

Beta function at IP 1, 2, 5, 8 (m)Beta function at IP 1, 2, 5, 8 (m) 0.55,10,0.55,100.55,10,0.55,10

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Related parametersRelated parameters

Luminosity in IP 1 & 5 (cmLuminosity in IP 1 & 5 (cm-2-2 s s-1-1)) 10103434

Luminosity in IP 2 & 8 (cmLuminosity in IP 2 & 8 (cm-2-2 s s-1-1)) ~5 10~5 103232

Transverse beam size at IP 1 & 5 (Transverse beam size at IP 1 & 5 (m)m) 16.716.7

Transverse beam size at IP 2 & 8 (Transverse beam size at IP 2 & 8 (m)m) 70.970.9

Stored energy per beam (MJ)Stored energy per beam (MJ) 362362

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28082808 is a lot of bunches per beam is a lot of bunches per beam

Filling scheme requires Filling scheme requires 12 SPS cycles per 12 SPS cycles per beambeam

Each with 2,3 or 4 Each with 2,3 or 4 batches of 72 bunchesbatches of 72 bunches

Crossing angle neededCrossing angle needed Emittance conservation with 10Emittance conservation with 101111

protons per bunch throughprotons per bunch through InjectingInjecting RampingRamping Squeezing to 0.55mSqueezing to 0.55m

This is going to take us a little This is going to take us a little while !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!while !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


362MJ362MJ is a lot of beam energy to handle is a lot of beam energy to handle


So how to get there ?So how to get there ?

Both machine and experiments will have to learn how to stand running Both machine and experiments will have to learn how to stand running at nominal intensitiesat nominal intensities

An early aim is to find a balance between robust operation and An early aim is to find a balance between robust operation and satisfying the experimentssatisfying the experiments

Maximize integrated luminosityMaximize integrated luminosity Minimize event pile-up (to event + 2)Minimize event pile-up (to event + 2)

Avoid quenches (and damage)Avoid quenches (and damage) Higher Higher ** to avoid problems in the (later part of) the squeeze to avoid problems in the (later part of) the squeeze Reduce total current to reduce stored beam energyReduce total current to reduce stored beam energy

Lower iLower ibb

Fewer bunchesFewer bunches Reduce energy to get more margin ?Reduce energy to get more margin ?

Against transient beam lossesAgainst transient beam losses Against magnet operating close to training limitAgainst magnet operating close to training limit Hardware commissioning will tell us moreHardware commissioning will tell us more


Other considerationsOther considerations

Electron cloud ( LHC simulations and SPS experience )Electron cloud ( LHC simulations and SPS experience ) iibb < 35% nominal for 25ns spacing < 35% nominal for 25ns spacing iibb ~ nominal for > 50ns ~ nominal for > 50ns

With With lower currentslower currents in mind, two machine systems will be staged in mind, two machine systems will be staged Only 8 of 20 beam dump dilution kickers initially installedOnly 8 of 20 beam dump dilution kickers initially installed

Total beam intensity < 50% nominalTotal beam intensity < 50% nominal Install the rest when neededInstall the rest when needed

Collimators ( robustness, impedance and other issues )Collimators ( robustness, impedance and other issues ) Phased approachPhased approach Run at the impedance limit during phase IRun at the impedance limit during phase I

Lower currentsLower currents Higher Higher **

Under review!


Proposal for early proton runningProposal for early proton running

Phase I collimators and partial beam dumpPhase I collimators and partial beam dump

1.1. Pilot physics run with few bunchesPilot physics run with few bunches No parasitic bunch crossingsNo parasitic bunch crossings Machine de-bugging no crossing angleMachine de-bugging no crossing angle 43 bunches, unsqueezed, low intensity43 bunches, unsqueezed, low intensity Push performance (156 bunches, partial squeeze in 1 and 5, push intensity)Push performance (156 bunches, partial squeeze in 1 and 5, push intensity)

2.2. 75ns operation75ns operation Establish multi-bunch operationEstablish multi-bunch operation Relaxed machine parameters (squeeze and crossing angle)Relaxed machine parameters (squeeze and crossing angle) Push squeeze and crossing angle Push squeeze and crossing angle

3.3. 25ns operation with Phase I collimators + partial beam dump25ns operation with Phase I collimators + partial beam dump Needs scrubbing for higher intensities ( iNeeds scrubbing for higher intensities ( ibb > 3 - 4 10 > 3 - 4 101010 ) )

Phase II collimators and full beam dumpPhase II collimators and full beam dump

4.4. 25ns operation25ns operation Push towards nominal performancePush towards nominal performance


Commissioning for Stage 1Commissioning for Stage 1 - From Chamonix XIV -

- 450GeV machine -


Commissioning for Stage 1Commissioning for Stage 1- From Chamonix XIV -

- Ramp and Squeeze -



- 450GeV machine - - Ramp and Squeeze -


Along the wayAlong the way

Equipment commissioning with beamEquipment commissioning with beam Machine protection commissioningMachine protection commissioning Instrumentation commissioningInstrumentation commissioning

First turn i.e. immediatelyFirst turn i.e. immediately Screens, BPMs, fast BCT, BLMsScreens, BPMs, fast BCT, BLMs

Circulating beams at 450 GeVCirculating beams at 450 GeV BPMs, DC BCT & lifetime, BLMsBPMs, DC BCT & lifetime, BLMs Transverse diagnosticsTransverse diagnostics Emittance: wire scanners..Emittance: wire scanners..

Snapback and RampSnapback and Ramp Chromaticity, PLLChromaticity, PLL OrbitOrbit BLMs to BIC etc.BLMs to BIC etc.

Checks with beam Checks with beam BPM Polarity, corrector polarity, BPM responseBPM Polarity, corrector polarity, BPM response

Beam measurementsBeam measurements beam parameter adjustment, energy, linear optics checks, aperture beam parameter adjustment, energy, linear optics checks, aperture etc. etc.etc. etc.



Stage 1 – pilot run luminositiesStage 1 – pilot run luminosities

No squeeze to startNo squeeze to start 43 bunches per beam (some displaced in one beam for LHCb)43 bunches per beam (some displaced in one beam for LHCb) Around 10Around 101010 per bunch per bunch Push one or all ofPush one or all of

Partial optics squeeze in 1 and 5 (2m ???)Partial optics squeeze in 1 and 5 (2m ???) Increase bunch intensityIncrease bunch intensity 156 bunches per beam (some displaced in one beam for LHCb)156 bunches per beam (some displaced in one beam for LHCb)

Beam energy (TeV)Beam energy (TeV) 6.0, 6.5 or 7.0 6.0, 6.5 or 7.0 6.0, 6.5 or 7.0

Number of bunches per beamNumber of bunches per beam 43 43 156

* in IP 1, 2, 5, 8 (m)* in IP 1, 2, 5, 8 (m) 18,10,18,10 2,10,2,10 2,10,2,10

Crossing Angle (Crossing Angle (rad)rad) 0 0 0

Transverse emittance (Transverse emittance (m radm rad)) 3.75 3.75 3.75

Bunch spacing (Bunch spacing (s)s) 2.025 2.025 0.525

Bunch IntensityBunch Intensity 1 1010 4 1010 4 1010

Luminosity IP 1 & 5 (cmLuminosity IP 1 & 5 (cm-2-2 s s-1-1)) ~ 3 1028 ~ 5 1030 ~ 2 1031

Luminosity IP 2 (cmLuminosity IP 2 (cm-2-2 s s-1-1)) ~ 6 1028 ~ 1 1030 ~ 4 1030

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Stage 2 – 75ns luminositiesStage 2 – 75ns luminosities

Partial squeeze and smaller crossing angle to startPartial squeeze and smaller crossing angle to start Luminosity tuning, limited by event pileupLuminosity tuning, limited by event pileup Establish routine operation in this modeEstablish routine operation in this mode Move towards nominal squeeze (1m ???) and crossing angleMove towards nominal squeeze (1m ???) and crossing angle Increase bunch intensity ?Increase bunch intensity ? Tune IP2 and IP8 to meet experimental needsTune IP2 and IP8 to meet experimental needs

Down in IP8 (1m ???)Down in IP8 (1m ???) Up in IP2 (50m ??? Then transverse beam displacement probably needed)Up in IP2 (50m ??? Then transverse beam displacement probably needed)

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* in IP 1, 2, 5, 8 (m)* in IP 1, 2, 5, 8 (m) 2,10,2,10 1,10,1,10 1,10,1,10



Bunch IntensityBunch Intensity 4 1010 4 1010 9 1010




Production physics runningProduction physics running Start with bunch intensities below electron cloud thresholdStart with bunch intensities below electron cloud threshold Scrubbing run (1-2 weeks)Scrubbing run (1-2 weeks) Increase bunch intensities to beam dump & collimator limitIncrease bunch intensities to beam dump & collimator limit

Install beam dump kickers Install beam dump kickers Install phase II collimatorsInstall phase II collimators

Increase bunch intensities towards nominalIncrease bunch intensities towards nominal Tune IP2 and IP8 to meet experimental needsTune IP2 and IP8 to meet experimental needs

Transverse beam displacement certainly needed in IP2Transverse beam displacement certainly needed in IP2

Stage 3 & 4 – 25ns luminositiesStage 3 & 4 – 25ns luminosities FfkN

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Beam energy (TeV)Beam energy (TeV) 6.0, 6.5 or 7.0 6.0, 6.5 or 7.0 7.0


* in IP 1, 2, 5, 8 (m)* in IP 1, 2, 5, 8 (m) 1,10,1,10 1,10,1,10 0.55,10,0.55,10



Bunch IntensityBunch Intensity 3 1010 5 1010 1.15 1011

Luminosity IP 1 & 5 (cmLuminosity IP 1 & 5 (cm-2-2 s s-1-1)) ~ 4 1032 ~ 1 1033 1034


Long shutdown (6months)


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Physics PreparePhysics

** adjustments - Squeeze adjustments - Squeeze

SqueezeGoing to be tricky to set up in any case (Optics changes and collimators)Foresee to do it after ramp to physics energy

• IP 1 and 5 to 2m or maybe 1m should become routine• IP 8 to values between 10m and 1m more tricky• IP 2 to values between 10m and 50m more tricky

Squeezing at other energies will be even more tricky• Stick with injection optics at lower energies ?


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FillingFilling

SchemeScheme Number Number of of bunches bunches per ringper ring

Nominal Nominal bunch bunch spacing spacing ((μμs)s)

Number Number of of bunches bunches in PSin PS

SPS filling pattern SPS filling pattern (number of PS cycles (number of PS cycles per SPS cycle and per SPS cycle and number of SPS cycles)number of SPS cycles)

SPS SPS cycle cycle length length (s)(s)

Filling Filling time per time per ring ring (min)(min)

4343 4343 2.0252.025 11 244 344 344 344 244 344 344 344

(12 SPS cycles, 43 PS cycles)(12 SPS cycles, 43 PS cycles)21.621.6 ~ 4~ 4

156156 156156 0.5250.525 44 234 334 334 334 234 334 334 334


75ns75ns 936936 0.0750.075 2424 234 334 334 334 234 334 334 334


25ns25ns 28082808 0.0250.025 7272 234 334 334 334 234 334 334 334


FillingAll the beams below have been made, but …Complicated scheme for all physics runs• 12 SPS cycles per LHC ring• Procedures defined (LHC is the master)• Need to demonstrate that we can do it• Reliability implications for injectors• Compounded by LHCb magnet polarity switch


IonsIons

Experiment sideExperiment side ALICE, ATLAS and CMS will all take Pb-Pb dataALICE, ATLAS and CMS will all take Pb-Pb data Detectors and machine will be already commissioned with ppDetectors and machine will be already commissioned with pp ALICE requests ALICE requests

4 week ion runs at the end of each year4 week ion runs at the end of each year first short run as early as possiblefirst short run as early as possible

Machine sideMachine side Start with early ion scheme (62 bunches instead of 592, 7 10Start with early ion scheme (62 bunches instead of 592, 7 1077 ions per bunch) ions per bunch) Will have to Will have to

Re-commission injection, first turnRe-commission injection, first turn Set up RF capture and instrumentationSet up RF capture and instrumentation Re-commission ramp and squeezeRe-commission ramp and squeeze Establish collisionsEstablish collisions

Could do (some of) this early on if injectors are ready (same optics as for p)Could do (some of) this early on if injectors are ready (same optics as for p) Ion runs could provide cool down of PS SPS LHC after proton operationIon runs could provide cool down of PS SPS LHC after proton operation After early ion scheme run, increase number of bunchesAfter early ion scheme run, increase number of bunches Move to nominal when possible Move to nominal when possible

Estimate 1-3 weeks for first setup

Followed by physics run



Ion filling and luminositiesIon filling and luminosities

EarlyEarly NominalNominal

Beam energy / nucleon (TeV)Beam energy / nucleon (TeV) 2.76 2.76

Number of bunches (per beam)Number of bunches (per beam) 62 592

* in IP 2 (m)* in IP 2 (m) 1 0.5

Crossing Angle (Crossing Angle (rad)rad) 0 0

Transverse emittance (Transverse emittance (m radm rad)) 1.5 1.5

Bunch spacing (Bunch spacing (s)s) 0.099 1.350

Bunch IntensityBunch Intensity 7 107 7 107

Luminosity in IP2 (cmLuminosity in IP2 (cm-2-2 s s-1-1)) ~ 5 1025 1027

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SchemeScheme Number Number of of bunches bunches per ringper ring

Nominal Nominal bunch bunch spacing spacing ((μμs)s)

Number Number of of bunches bunches in PSin PS

SPS filling pattern SPS filling pattern (number of PS cycles (number of PS cycles per SPS cycle and per SPS cycle and number of SPS cycles)number of SPS cycles)

SPS SPS cycle cycle length length (s)(s)

Filling Filling time per time per ring ring (min)(min)

Early ionEarly ion 6262 1.3501.350 11 2444 4444 4444 4444 2444 4444 4444 4444


Nominal ionNominal ion 592592 0.1000.100 44 81313 121313 121313 12131381313 121313 121313 121313

(12 SPS cycles, 148 PS cycles)(12 SPS cycles, 148 PS cycles)5454 ~ 10~ 10


TOTEMTOTEM

A standard TOTEM year would beA standard TOTEM year would be σσtot tot measurement high prioritymeasurement high priority

Nominal emittance OK for Nominal emittance OK for σσtottot, 1 , 1 μμm needed for elastic scatteringm needed for elastic scattering 3 * 1 day runs at 3 * 1 day runs at * of 1540m with 43 or 156 bunches per beam * of 1540m with 43 or 156 bunches per beam 2 * 1 day runs at 2 * 1 day runs at * of 18m with 2808 bunches per beam (25ns)* of 18m with 2808 bunches per beam (25ns)

ATLAS requests a period of a few weeks after first years of runningATLAS requests a period of a few weeks after first years of running

Machine sideMachine side Special machine conditions, similar to polarisation runs at LEPSpecial machine conditions, similar to polarisation runs at LEP Very demanding on beam and optics quality, and for collimationVery demanding on beam and optics quality, and for collimation Initial setup will take several days (maybe better dispersed)Initial setup will take several days (maybe better dispersed) Subsequent setups should take a shift or twoSubsequent setups should take a shift or two Longer runs may be more efficient if machine reproducibility is an issueLonger runs may be more efficient if machine reproducibility is an issue



TOTEM luminositiesTOTEM luminosities

Total Cross Section and Elastic scatteringTotal Cross Section and Elastic scattering Diffraction and minimum biasDiffraction and minimum bias Characterized byCharacterized by

Several 1 day runs per year (starting early)Several 1 day runs per year (starting early) Some single beam runsSome single beam runs 43 and 156 bunches per beam (as during Stage 1)43 and 156 bunches per beam (as during Stage 1) IP5 IP5 ** = 1540m = 1540m IP5 IP5 ** = 18m = 18m



* in IP 5 (m)* in IP 5 (m) 1540 1540 18



Bunch spacing (Bunch spacing (s)s) 2.025 0.525 0.025

Bunch IntensityBunch Intensity 3 1010 6 1010 1.15 1011

Luminosity IP 5 (cmLuminosity IP 5 (cm-2-2 s s-1-1)) ~ 4 1027 ~ 6 1028 ~ 3 1032

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SchedulingScheduling

Every year we will need a long shutdown (3-4 months)Every year we will need a long shutdown (3-4 months)

At the end of every shutdownAt the end of every shutdown Close the machine personnel access systemClose the machine personnel access system Get all equipment ready for beam (machine checkout, ~ 4 weeks)Get all equipment ready for beam (machine checkout, ~ 4 weeks) Get machine ready for operation (setup with beam, 2-3 weeks)Get machine ready for operation (setup with beam, 2-3 weeks)

During periods of operationDuring periods of operation Need regular technical stops (3 days every month)Need regular technical stops (3 days every month)

Interventions need careful but flexible planningInterventions need careful but flexible planning Get machine ready for operation (1 day)Get machine ready for operation (1 day) Machine development (around 15% during first years)Machine development (around 15% during first years) Operations for physicsOperations for physics Access as required for unscheduled stopsAccess as required for unscheduled stops



Breakdown of a normal yearBreakdown of a normal year

7

140 days for physics per yearNot forgetting ion and TOTEM operation

Leaves ~ 100 days for proton luminosity running? Efficiency for physics 40% ?

40 days ~ 1000 h ~ 4 106 s of colliding beams / year



So the first few years could look like …So the first few years could look like …

Starting in 07, phase II collimators in 09/10Starting in 07, phase II collimators in 09/10

initial operation & requirements on the machine

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