Large Hadron Collider at CERN

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1 Large Hadron Collider at CERN Steve Playfer 27km circumference depth m University of Edinburgh 15th Novemebr Status of the LHC - Steve Playfer 1

2 Status of the LHC - Steve Playfer 2

3 LHC vital statistics Will eventually collide two 7 TeV proton beams with beam currents of 600mA E=mc 2 gives 14TeV=>0.15g (a fly) Total energy stored in beam is 350MJ (90kg of TNT) Uses 1232 superconducting NbTi dipole magnets to bend beams round the ring Beam pipe has vacuum of 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 Current status at Status of the LHC - Steve Playfer 3

4 LHC Dipoles Magnets are cooled to 1.9K by superfluid 3 He Field ramps from 0.5T to 8.3T during injection Both beams are in the same cryostat Status of the LHC - Steve Playfer 4

5 Today all the magnets are cold Cool-down time is 4 weeks/sector Four Experiments (ALICE, ATLAS, CMS, LHCb) SPS ring injects 400GeV protons ALICE Experiment Status of the LHC - Steve Playfer

6 LHC RF Cavities Needed to accelerate beams from 400GeV to 7TeV after injection Also needed to replace synchrotron energy losses during stable beam delivery (collisions) 8 cavities/beam Frequency 400 MHz Accelerating gradient 5MV/m Status of the LHC - Steve Playfer 6

7 LHC Operation Proton beams are injected from the SPS at 400GeV and 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 in each direction. Each bunch contains protons and travels round the ring in 0.9ms. The bunch spacing is ~7m or 25ns, the bunch length is 7.5cm, and the crossing rate is 40MHz at each of the four interaction points (ATLAS, CMS, LHCb, ALICE). At full luminosity (10 34 /cm 2 /s) there will be several interactions during each bunch crossing. The expected data rate is 100MB/s per experiment or ~10 PetaBytes/year! Status of the LHC - Steve Playfer 7

8 LHC turn-on 10/9/08 Big media publicity day (I was at the Scottish parliament) Proton beams were circulated in each direction for a short time Status of the LHC - Steve Playfer 8

9 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 a cryogenic circuit causing a large liquid Helium leak (6 Tonnes) Energy released as pressure wave was sufficient to damage several magnets Safety interlocks restricted damage to one sector Status of the LHC - Steve Playfer 9

10 The culprit: a bus-bar joint bus-bar joints in the LHC main circuits joints are at the interconnection between magnets. They are welded in the tunnel. Nominal joint resistance: 1.6 K 300K 300pΩ ~10µΩ For the LHC to operate safely at a certain energy, there is a limit to the maximum value of the joint resistance Status of the LHC - Steve Playfer 10

11 2008/9 - LHC repair and consolidation 14 quadrupole magnets replaced 39 dipole magnets replaced 204 electrical interconnections repaired Over 4km of vacuum beam tube cleaned New longitudinal restraining system for 50 quadrupoles Almost 900 new helium 6500 new detectors and 250km cables pressure release ports for new Quench Protection System to protect from busbar quenches 11 Status of the LHC - Steve Playfer

12 November/December th Nov Day 0 Both beams circulating after 6 hours 23 rd Nov Day 3 First pilot collisions at 450 GeV 29 th Nov Day 9 Beams ramped to 1.18 TeV 6 th Dec Day 16 Stable 450 GeV for the experiments 8 th Dec Day 18 Both beams ramped to 1.18 TeV first collisions Low luminosity, but all four experiments observed collisions First papers (on inclusive charged track multiplicity) have already appeared. Results are being presented this week (Moriond QCD) Status of the LHC - Steve Playfer 12

13 (Ambitious) goal : each experiment collects an integrated 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 level before further improvements to machine in 2012) Run /cm 2 /s Beams injected this month. About to accelerate them to 3.5TeV /cm 2 /s First collisions at the end of the month? April July November Status of the LHC - Steve Playfer

14 LHC Detectors ATLAS is a general purpose detector (GPD) 46mx25mx25m, 7000Tonnes, central magnetic solenoid 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 dipole bending magnet (4Tm) Designed to study b quarks Collaboration has 700 physicists (20% from UK) ALICE is designed to look at heavy ion collisions Status of the LHC - Steve Playfer 14

15 ATLAS Status of the LHC - Steve Playfer 15

16 Status of the LHC - Steve Playfer 16

17 CMS Status of the LHC - Steve Playfer 17

18 Status of the LHC - Steve Playfer 18

19 LHCb Bending Magnet Muon detectors Particle Calorimeter ID (RICH) Tracking System Status of the LHC - Steve Playfer Vertex Locator 19 Décembre 2005

20 Λ p π Status of the LHC - Steve Playfer 20

21 First Physics Results ALICE EPJC 65:111 (2010) Number of charged tracks as a function of (pseudo)rapidity is rather flat National Geographic News (4th Dec).a machine called ALICE... found that a proton-proton collision recorded on November 23rd created the precise ratio of matter and antimatter particles predicted from theory Status of the LHC - Steve Playfer 21

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

23 CMS First Results C.Roland (Moriond QCD 2010) Transverse momentum spectrum is as expected Status of the LHC - Steve Playfer 23

24 LHCb First Results M.Knecht (Moriond QCD 2010) Inclusive K S production in the forward direction Status of the LHC - Steve Playfer 24

25 Long Term LHC Schedule Big shutdown in 2012 to make machine safe to operate at full beam energy of 7 TeV Then there will be long 18 month runs separated by shorter 6 month shutdowns Peak luminosity will gradually increase (x2/year?) There will improvements to the injectors ( ) Eventually there will be upgrades to the detectors ( ?) My optimistic scenario - Find evidence for supersymmetry in Find Higgs boson(s) by Status of the LHC - Steve Playfer 25

26 Why the LHC won t destroy the world Centre of mass energy of proton-proton collisions E CM =14TeV Can be achieved by colliding a high energy proton with a proton at rest E CM = sqrt(2e p m p ) with E p ~10 5 TeV Primary cosmic rays (protons) interact with the Earth s upper atmosphere. Highest observed energy cosmic rays are E p ~10 8 TeV which gives E CM >>14TeV. There are even more energetic collisions in the centres of galaxies, black holes etc. LHC collisions are the highest energy in a laboratory Status of the LHC - Steve Playfer 26