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Merlin

Merlin. H. Rafique , R. Barlow, J. Molson. A C++ Class Library for Collimation Studies. 0 / 174. The LHC The LHC Beam Collimation – what? Collimation – why? Merlin Future. Ingredients. 1 / 174. The Large Hadron Collider. Circumference = 26.659 km

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Merlin

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  1. Merlin H. Rafique, R. Barlow, J. Molson A C++ Class Library for Collimation Studies 0 / 174

  2. The LHC The LHC Beam Collimation – what? Collimation – why? Merlin Future Ingredients 1 / 174

  3. The Large Hadron Collider Circumference = 26.659 km Nominal Beam Energy = 7TeV (proton) Nominal Collision CoM Energy = 14TeV (proton – proton) Nominal stored energy of beams = 350 MJ Ultra High Vacuum < 1E-9 mbar Superconducting NbTi Magnets – up to 8.33T Supercooled via 700,000litres of superfluid He @ 1.9K Largest cryogenic centre in the world 1232 main dipoles (bending magnets) ~850quadrupoles (focussing magnets) ~6200 higher order correcting magnets 2 / 174

  4. The LHC 3 / 174

  5. The LHC • Injection from SPS450 GeV • Beam accelerated using 400.8MHz RF cavities • Dipole magnets operate up to 8.33T • Quads & other magnets focus and correct beam optics • 2009: E = 3.5TeV • 2012: E = 4TeV • 2014: E = 7TeV • Per beam 4 / 174

  6. The LHC Beam y • ‘Beam’ consists of many ‘bunches’ of particles (usually protons) • The bunch distribution is approximately gaussian • Beam halo refers to the gaussian tails i.e. particles with amplitude larger than given aperture size x 5 / 174

  7. Beam Halo & Blow Up The beam halo is populated due to various phenomena: EM fields from: • Counter-rotating beam Particles in the bunch scatter off of: • Other bunch particles • Coasting beam • Gas in the vacuum • Apertures Other: • Synchrotron radiation, power radiated: 3.9 kW @ 7 TeV, 66 mW @ 450 GeV 6 / 174

  8. Collimation – what? OED: Collimator: A device for producing a parallel beam of rays or radiation. In this case: removal / cleaning of unwanted particles from the accelerator 7 / 174

  9. Collimation – why? Protect superconducting magnets – avoid quenches Max beam loss at 7 TeV(1% of beam over 10s) = 500 kW Quench limit of SC LHC magnet = 8.5 W/m [1] Remove ‘stray’ particles before collision Act as emergency beam dump – TCDQ Protect valuable ‘triplet’ quadrupoles used to maximise luminosity at Interaction Points [1] R. Aßmann,The Final LHC Collimation system, EPAC06 8 / 174

  10. Crossing in IP1 (ATLAS) 9 / 174

  11. Collimation Hardware Required efficiency > 99.9% (No of absorbed protons : No that can reach normalised mechanical aperture at 10 σ)[1] <0.00002% of protons hitting the collimators may escape to impact upon a SC magnet [2] System comprises of ~140 collimators / absorbers in IR3 and IR7 [1] R. Aßmann et al. Requirements for the LHC collimation system, CERN Proj. Rep. 599 [2] G. Robert-Demolaize, CERN Thesis 2006-069 10 / 174

  12. Merlin 11 / 174

  13. MAD Interface • MAD .tfs table output • Construct accelerator • Useful for large accelerators (i.e. LHC) MADInterface* myMADInterface = new MADInterface(“input.tfs”, EnergyInGeV); AcceleratorModel* myModel = myMADInterface->ConstructModel(); 12 / 174

  14. Accelerator Model • Can be created from XTFF or MAD Interface • Can be created from Accelerator Components in user code • Once created can be further modified and manipulated e.g. alignment errors added • Each element has an associated EM Field, Geometry, Aperture and Wake Potentials AcceleratorModelConstructor* myAccCtor = new AcceleratorModelConstructor(); myAccCtor->NewModel(); Quadrupole* quad = new Quadrupole( “name”, Length, K1 ); myAccCtor->AppendComponent( *quad ); Collimator* coll = new Collimator (“coll”, Length, Material, ScatteringProcess, momentum); Aperture* ap = new CircularAperture( .0002 ); coll -> SetAperture( ap ); myAccCtor -> AppendComponent( *coll); AcceleratorModel* mymodel = myAccCtor -> GetModel(); 13 / 174

  15. Physics Processes • Can apply additional physics at selected elements and positions • Scattering at collimators when particle amplitude > aperture • Synchrotron radiation • Wakefields • Stepping managed by trackers ScatteringModel* myScatter= new ScatteringModel; myScatter-> AddProcess( new Process() ); myScatter-> AddProcess( new Inelastic() ); CollimateProtonProcess* myCollimateProcess= new CollimateProtonProcess(0,7); myCollimateProcess->ScatterAtCollimator(true); 14 / 174

  16. Materials • Collimator interactions depend on material • Collimators can have materials from the StandardMaterials database or user made materials MaterialProperties*Uo = new MaterialProperties(Atomic Mass, Atomic Number, Sigma_E, Sigma_I, Sigma_R, dEdx, Radiation Length, Density, Conductivity, MeanExcitationEnergy); MaterialProperties*Be = new MaterialProperties(9.012182, 4, 0.069, 0.199, 0.000035, 1.594, 65.19, 1.848, 3.08E7, (63.7*eV)); Be.PrintTable(); Materialsmix1; mix1.StandardMaterials(); mix1.MakeMixture (“Mix1”, “Al Cu W”, 1, 2, 3, 77., 56.); mix1.PrintTable(); 15 / 174

  17. Beam • Defining a beams properties, from which a bunch is constructed BeamDatamybeam; mybeam.charge = 1.31e11; mybeam.beta_x= 0.5495121695 * meter; mybeam.beta_y= 0.5498820579 * meter; mybeam.emit_x = 33.640 * 5.026457122e-10 * meter; mybeam.emit_y = 33.64 * 5.026457122e-10 * meter; mybeam.sig_z= 75.5 * millimeter; mybeam.sig_dp= 0.000113; mybeam.p0 = 7000*GeV; mybeam.yp0 = 0; mybeam.xp0 = 0; mybeam.x0 = 0; mybeam.y0 = 0; mybeam.alpha_x= -0.0001721885021 * meter; mybeam.alpha_y= -0.0004654580947 * meter; intno_part= 1E6; ParticleBunch* myInitialBunch = ParticleBunchConstructor (mybeam,n0_part, Distribution).ConstructParticleBunch(); 16 / 174

  18. Tracker • Takes bunch and beamline inputs, tracks bunch along the beamline • Can use specific integrator sets such as TRANSPORT, Thin Lens, and Symplectic • Can step along the accelerator lattice and within accelerator components ParticleBunch* myInitialBunch = ParticleBunchConstructor (mybeam, n0_part, Distribution).ConstructParticleBunch(); ParticleTracker*mytracker= new ParticleTracker(mymodel ->GetBeamline(), myInitialBunch); mytracker-> AddProcess (myCollimateProcess); ParticleBunch* myFinalBunch; myFinalBunch = mytracker -> Track (myInitialBunch); 17 / 174

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  20. The Future of the LHC 2013 Shutdown: upgrade to design E = 7 TeVand L = 1 x 1034 cm2 s-1 2020 HiLumi LHC: Increased L 5 x current design L = 5x 1034 cm2s-1 New hardware e.g. Crystal Collimators? 19 / 174

  21. Acknowledgements Prof. Roger Barlow Huddersfield James Molson Manchester Dr. Stefano Redaelli Dr.RoderikBruce Dr.ValentinaPrevitali Elena Quarenta CERN BE-ABP NGACDT EPSRC Thank You Proton – Lead ion collision, ALICE 13.09.12 174 / 174

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