17.03.2010 Der LHC Beschleuniger - DPG - Bonn 1 Drawing by Sergio Cittolin Der LHC Beschleuniger: Herausforderungen auf dem Weg zu Teilchenkollisionen

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  • 17.03.2010Der LHC Beschleuniger - DPG - Bonn*Drawing by Sergio CittolinDer LHC Beschleuniger: Herausforderungen auf dem Weg zu TeilchenkollisionenJ. Wenninger CERN

    Der LHC Beschleuniger - DPG - Bonn

  • Outline17.03.2010Der LHC Beschleuniger - DPG - Bonn*IntroductionInstallation and preparation for beamIncident in sector 34, repair and consequencesLHC beam operationConclusions

    Der LHC Beschleuniger - DPG - Bonn

  • 17.03.2010Der LHC Beschleuniger - DPG - BonnThe Large Hadron Collider LHC*CMS, TotemATLAS, LHCfLHCbALICELake of GenevaInstalled in 26.7 km LEP tunnelDepth of 70-140 mControl RoomLHC ringSPS ring

    Der LHC Beschleuniger - DPG - Bonn

  • ATLAS17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • CMS17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • LHCb17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • ALICE17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • TOTEM and LHCf17.03.2010Der LHC Beschleuniger - DPG - Bonn*Total X-section, elastic and diffractive scattering.Forward production of neutral particles (cosmic ray shower modeling)

    Der LHC Beschleuniger - DPG - Bonn

  • Collider luminosity17.03.2010Der LHC Beschleuniger - DPG - Bonn*Thus, to achieve high luminosity, all one has to do is make (lots of) high population bunches of low emittance to collide at high frequency at locations where the beam optics provides as low values of the amplitude functions as possible. PDG 2005, chapter 25Parameters:Number of particles per bunchNumber of bunches per beamkb

    Beam sizes at the collision points

    Revolution frequencyfCrossing angle factorF ~ 1Collision rate is proportional to luminosityInteraction RegionBeam quality (emittance)Intensity

    Der LHC Beschleuniger - DPG - Bonn

  • LHC challenges17.03.2010Der LHC Beschleuniger - DPG - Bonn*The LHC surpasses existing accelerators/colliders in 2 aspects :The energy of the beam of 7 TeV that is achieved within the size constraints of the existing 26.7 km LEP tunnel.LHC dipole field8.3 THERA/Tevatron ~ 4 TThe luminosity of the collider that will reach unprecedented values for a hadron machine:LHC pp ~ 1034 cm-2 s-1Tevatron pp3x1032 cm-2 s-1SppSpp6x1030 cm-2 s-1Very high field magnets and very high beam intensities:Operating the LHC is a great challenge.There is a significant risk to the equipment and experiments.A factor 2 in fieldA factor 4 in sizeA factor 30 in luminosity

    Der LHC Beschleuniger - DPG - Bonn

  • LHC dipole magnet17.03.2010Der LHC Beschleuniger - DPG - Bonn*1232 dipole magnets.B field 8.3 T (11.8 kA) @ 1.9 K (super-fluid Helium)2 magnets-in-one design : two beam tubes with an opening of 56 mm.Operating challenges:Dynamic field changes at injection.Very low quench levels (~ mJ/cm3)

    Der LHC Beschleuniger - DPG - Bonn

  • Stored energy17.03.2010Der LHC Beschleuniger - DPG - Bonn*Increase with respect to existing accelerators :A factor 2 in magnetic fieldA factor 7 in beam energyA factor 200 in stored beam energyDamage threshold

    Der LHC Beschleuniger - DPG - Bonn

  • Collimation17.03.2010Der LHC Beschleuniger - DPG - Bonn*To operate at nominal performance the LHC requires a large and complex collimation systemPrevious colliders used collimators mostly for experimental background conditions.Ensure cohabitation of:360 MJ of stored beam energy, super-conducting magnets with quench limits of few mJ/cm3 Almost 100 collimators and absorbers.Alignment tolerances < 0.1 mm to ensure that over 99.99% of the protons are intercepted.Primary and secondary collimators are made of Carbon to survive large beam loss.

    Der LHC Beschleuniger - DPG - Bonn

  • Outline17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • Installation17.03.2010Der LHC Beschleuniger - DPG - Bonn*Transport in the tunnel with an optically guided vehicle.Approximately 1600 magnet assemblies transported over up to 20 km at 3 km/hour.First dipole lowered March 2005.Magnet installation until spring 2007Interconnection work finished end 2007

    Der LHC Beschleuniger - DPG - Bonn

  • 3 km long arc cryostat17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • LHC cool-down 200817.03.2010Der LHC Beschleuniger - DPG - Bonn*Cool-down time to 1.9 K is nowadays ~4 weeks/sector[sector = 1/8 LHC]

    Der LHC Beschleuniger - DPG - Bonn

  • LHC Hardware Commissioning17.03.2010Der LHC Beschleuniger - DPG - Bonn*Commissioning of the magnets & circuits (power converter, quench protection, interlocks..) follows predefined test steps. 1700 circuits, 10000 magnetsCommissioning time ~5 months

    Der LHC Beschleuniger - DPG - Bonn

  • September 10th - control (show) room17.03.2010Der LHC Beschleuniger - DPG - Bonn*For 3 days all went perfectly well with beam

    Der LHC Beschleuniger - DPG - Bonn

  • Outline17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • Incident of Sept. 19th 200817.03.2010Der LHC Beschleuniger - DPG - Bonn*The final circuit commissioning was performed in the week following the startup with beam. During the last commissioning step of the last main dipole circuit an electrical fault developed at ~5.2 TeV (8.7 kA) in the dipole bus bar (cable) at the interconnection between a quadrupole and a dipole magnet.Later correlated to quench due to a local R ~220 nW nominal 0.35 nW. An electrical arc developed and punctured the helium enclosure.Around 400 MJ from a total of 600 MJ stored in the circuit were dissipated in the cold-mass and in electrical arcs.Large amounts of Helium were released into the insulating vacuum.The pressure wave due to Helium flow was the cause of most of the damage (collateral damage).

    Der LHC Beschleuniger - DPG - Bonn

  • Magnet Interconnection17.03.2010Der LHC Beschleuniger - DPG - Bonn*Dipole busbar

    Der LHC Beschleuniger - DPG - Bonn

  • Collateral damage17.03.2010Der LHC Beschleuniger - DPG - Bonn*Quadrupole-dipole interconnectionQuadrupole supportMain damage area covers ~ 700 metres.39 out of 154 main dipoles,14 out of 47 main quadrupolesfrom the sector had to be moved to the surface for repair (16) or replacement (37).Sooth clad beam vacuum chamber

    Der LHC Beschleuniger - DPG - Bonn

  • Bus-bar joint17.03.2010Der LHC Beschleuniger - DPG - Bonn*24000 bus-bar joints in the LHC main circuits.10000 joints are at the interconnection between magnets. They are welded in the tunnel.

    Nominal joint resistance:1.9 K 0.3 n300K ~10 For the LHC to operate safely at a certain energy, there is a limit to maximum value of the joint resistance.

    Der LHC Beschleuniger - DPG - Bonn

  • Joint quality17.03.2010Der LHC Beschleuniger - DPG - Bonn*The copper stabilizes the bus bar in the event of a cable quench (=bypass for the current while the energy is extracted from the circuit).Protection system in place in 2008 not sufficiently sensitive.A copper bus bar with reduced continuity coupled to a superconducting cable badly soldered to the stabilizer can lead to a serious incident.During repair work in the damaged sector, inspection of the joints revealed systematic voids caused by the welding procedure.X-ray of joint

    Der LHC Beschleuniger - DPG - Bonn

  • LHC repair and consolidation17.03.2010Der LHC Beschleuniger - DPG - Bonn*14 quadrupole magnets replaced39 dipole magnets replaced204 electrical inter-connections repairedOver 4km of vacuum beam tube cleanedNew longitudinal restraining system for 50 quadrupoles

    Almost 900 new helium pressure release ports6500 new detectors and 250km cables for new Quench Protection System to protect from busbar quenchesCollateral damage mitigation

    Der LHC Beschleuniger - DPG - Bonn

  • LHC target energy: the way down17.03.2010Der LHC Beschleuniger - DPG - Bonn*2002-20077 TeVSummer 20085 TeVSpring 20093.5 TeVNov. 2009450 GeVDetrainingnQPS2 kA6 kA9 kAWhenWhy12 kALate 2008Joints1.18 TeVDesignAll main magnets commissioned for 7TeV operation before installation

    Detraining found when hardware commissioning sectors in 20085 TeV poses no problemDifficult to exceed 6 TeV

    Machine wide investigations following S34 incident showed problem with joints

    Commissioning of new Quench Protection System(nQPS)

    Der LHC Beschleuniger - DPG - Bonn

  • LHC target energy: the way up17.03.2010Der LHC Beschleuniger - DPG - Bonn*Train magnets6.5 TeV is in reach7 TeV will take timeRepair jointsComplete pressure relief system

    Commission nQPS system

    2014 ?2010TrainingStabilizersnQPSWhenWhat7 TeV3.5 TeV1.18 TeV450 GeV2011201320096 TeV

    Der LHC Beschleuniger - DPG - Bonn

  • Outline17.03.2010Der LHC Beschleuniger - DPG - Bonn*

    Der LHC Beschleuniger - DPG - Bonn

  • Reserve slides17.03.2010Der LHC Beschleuniger - DPG - Bonn*20th November 200914 months to repair, consolidate and re-commissioning all elements.Great relief on November 20th when both beams circulated again !!!

    Der LHC Beschleuniger - DPG - Bonn

  • 2009 beam operation milestones17.03.2010Der LHC Beschleuniger - DPG - Bonn*Many LHC systems were commissioned at forced pace aim to check as much as possible.Overall uptime ~60% - very good at this stage.Our most optimistic plan became true !!A touch of modestyThe stored energy did not exceed 30 kJ 0.01% of nominal.

    20th NovDay 0Both beams circulating after 6 hours23rd NovDay 3First pilot collisions at 450 GeV29th NovDay 9Beams ramped to 1.18 TeV6th DecDay 16Stable collisions @ 450 GeV for the exp