Large Hadron Collider at CERN - University of Edinburgh

Large Hadron Collider at CERNSteve Playfer27km circumferencedepth 70-140mUniversity of Edinburgh15th Novemebr 200817.03.2010 Status of the LHC - Steve Playfer1

17.03.2010 Status of the LHC - Steve Playfer2

LHC vital statistics• Will eventually collide two 7 TeV proton beams withbeam currents of 600mAE=mc 2 gives 14TeV=>0.15g (a fly)Total energy stored in beam is 350MJ (90kg of TNT)• Uses 1232 superconducting NbTi dipole magnets tobend beams round the ring• Beam pipe has vacuum of 10 -13 atmospheres• Total power required to run LHC is 120MW• Total cost to construct LHC was 3Billion Euros(not including tunnel which was constructed for LEP)More details on design at http://lhc.web.cern.ch/lhc/Current status at http://www.lhcportal.com/17.03.2010 Status of the LHC - Steve Playfer3

LHC Dipoles• Magnets are cooled to1.9K by superfluid 3 He• Field ramps from 0.5Tto 8.3T during injection• Both beams are in thesame cryostat17.03.2010 Status of the LHC - Steve Playfer4

Today all themagnets are coldCool-down timeis 4 weeks/sectorFour Experiments(ALICE, ATLAS, CMS, LHCb)SPS ring injects400GeV protonsALICEExperiment17.03.2010 5Status of the LHC - Steve Playfer

LHC RF Cavities• Needed to accelerate beams from 400GeV to7TeV after injection• Also needed to replace synchrotron energy lossesduring stablebeam delivery(collisions)• 8 cavities/beam• Frequency400 MHz• Acceleratinggradient 5MV/m17.03.2010 Status of the LHC - Steve Playfer6

LHC Operation• Proton beams are injected from the SPS at 400GeVand then accelerated to 7TeV. This is known as a “fill”.• The lifetime of the stored beams is ~10 hours.• There will eventually be 2808 bunches of protons ineach direction. Each bunch contains 10 11 protons andtravels round the ring in 0.9ms.• The bunch spacing is ~7m or 25ns, the bunch length is7.5cm, and the crossing rate is 40MHz at each of thefour interaction points (ATLAS, CMS, LHCb, ALICE).• At full luminosity (10 34 /cm 2 /s) there will be severalinteractions during each bunch crossing.• The expected data rate is 100MB/s per experiment or~10 PetaBytes/year!17.03.2010 Status of the LHC - Steve Playfer7

LHC turn-on 10/9/08Big media publicity day (I was at the Scottish parliament)Proton beams were circulated in each direction for a short time.17.03.2010 Status of the LHC - Steve Playfer8

The incident on 19/10/08• During power testing of a dipole magnet at high current (9kA)there was an electrical arc due to sudden high resistance.Dissipated 400MJ of energy very quickly.• Burnt a hole in acryogenic circuitcausing a large liquidHelium leak (6 Tonnes)• Energy released aspressure wave wassufficient to damageseveral magnets• Safety interlocksrestricted damage toone sector17.03.2010 Status of the LHC - Steve Playfer9

The culprit: a bus-bar joint 24’000 bus-bar joints in the LHC main circuits. 10’000 joints are at the interconnection between magnets.They are welded in the tunnel.Nominal jointresistance:• 1.6 K• 300K300pΩ~10µΩFor the LHC to operate safely at a certain energy, there is alimit to the maximum value of the joint resistance.17.03.2010 Status of the LHC - Steve Playfer 10

2008/9 - LHC repair andconsolidation14 quadrupolemagnets replaced39 dipole magnetsreplaced204 electrical interconnectionsrepairedOver 4km of vacuumbeam tube cleanedNew longitudinal restrainingsystem for 50 quadrupoles17.03.2010Almost 900 new helium 6500 new detectors and 250km cablespressure release ports for new Quench Protection System toprotect from busbar quenches11Status of the LHC - Steve Playfer

November/December 200920 th Nov Day 0 Both beams circulating after 6 hours23 rd Nov Day 3 First pilot collisions at 450 GeV29 th Nov Day 9 Beams ramped to 1.18 TeV6 th Dec Day 16 Stable collisions @ 450 GeV for the experiments8 th Dec Day 18 Both beams ramped to 1.18 TeV – first collisionsLow luminosity, but all four experiments observed collisionsFirst papers (on inclusive charged track multiplicity)have already appeared.Results are being presented this week (Moriond QCD)17.03.2010 Status of the LHC - Steve Playfer 12

(Ambitious) goal : each experiment collects anintegrated luminosity of 1 fb -1 of data Peak luminosity 2x10 32 /cm 2 /s (same as Tevatron) 700 bunches with 10 8 p/bunch (30MJ of stored energy) There will be a short heavy ion run in November 2010 Beam Energy will be 3.5TeV (maximum safe levelbefore further improvements to machine in 2012)2010-2011Run10 32 /cm 2 /sBeams injected this month.About to accelerate them to3.5TeV.10 31 /cm 2 /sFirst collisions at the end ofthe month?April July November17.03.2010 Status of the LHC - Steve Playfer 132010

LHC Detectors• ATLAS is a general purpose detector (GPD)46mx25mx25m, 7000Tonnes, central magneticsolenoid 2T and muon toroids 4T• CMS is another GPD, 21mx15mx15m,12500Tonnes, central magnetic solenoid 4T– GPDs look for new heavy particles– Each collaboration has 2000 physicists (10% from UK)• LHCb is a forward spectrometer with a dipolebending magnet (4Tm)– Designed to study b quarks– Collaboration has 700 physicists (20% from UK)• ALICE is designed to look at heavy ion collisions17.03.2010 Status of the LHC - Steve Playfer14

ATLAS17.03.2010 Status of the LHC - Steve Playfer15

17.03.2010 Status of the LHC - Steve Playfer16

CMS17.03.2010 Status of the LHC - Steve Playfer17

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LHCbMuondetectorsCalorimeterParticleID (RICH)BendingMagnetTrackingSystemVertexLocator17.03.2010 Status of the LHC - Steve Playfer19Décembre 2005

Λ → p π17.03.2010 Status of the LHC - Steve Playfer 20

First Physics ResultsALICEEPJC 65:111 (2010)Number of charged tracks as a functionof (pseudo)rapidity is rather flatNational GeographicNews (4th Dec)‘….a machine calledALICE....found that aproton-proton collisionrecordedon November 23rdcreated the preciseratio of matter andantimatter particlespredicted fromtheory..’17.03.2010 Status of the LHC - Steve Playfer 21

W.H.Bell (Moriond QCD 2010)17.03.2010 Status of the LHC - Steve Playfer 22

CMS First ResultsC.Roland (Moriond QCD 2010)Transverse momentum spectrumis as expected17.03.2010 Status of the LHC - Steve Playfer 23

LHCb First ResultsM.Knecht (Moriond QCD 2010)Inclusive K S production in the forward direction17.03.2010 Status of the LHC - Steve Playfer 24

Long Term LHC Schedule• Big shutdown in 2012 to make machine safe tooperate at full beam energy of 7 TeV• Then there will be long 18 month runs separated byshorter 6 month shutdowns• Peak luminosity will gradually increase (x2/year?)• There will improvements to the injectors (2015-2020)• Eventually there will be upgrades to the detectors(2016-2020?)My optimistic scenario…- Find evidence for supersymmetry in 2011- Find Higgs boson(s) by 201417.03.2010 Status of the LHC - Steve Playfer25

Why the LHC won’t destroy the worldCentre of mass energy of proton-proton collisions E CM =14TeVCan be achieved by colliding a high energy proton with aproton at rest E CM = sqrt(2E p m p ) with E p ~10 5 TeVPrimary cosmic rays (protons) interact with the Earth’supper atmosphere. Highest observed energy cosmic raysare E p ~10 8 TeV which gives E CM >>14TeV.There are even more energetic collisions in the centresof galaxies, black holes etc.LHC collisions are the highest energy in a laboratory17.03.2010 Status of the LHC - Steve Playfer26