R.Schmidt - Villa Olmo LHC tunnel Beam dump tunnel The LHC collider: Status and Outlook to Operation Rüdiger Schmidt - CERN 9th Villa Olmo Conference COMO 17 October 2005 Challenges The LHC accelerator complex Status Operation und Machine Protection

R.Schmidt - Villa Olmo Main Parameters and Challenges

LEP: e+e- 104 GeV/c ( ) Circumference 26.8 km LHC proton-proton Collider 7 TeV/c in the LEP tunnel (+ ion collider) 2 rings Injection from SPS at 450 GeV/c ATLAS CMS LHCB ALICE

R.Schmidt - Villa Olmo LHC: From first ideas to realisation 1982 : First studies for the LHC project 1983 : Z0 detected at SPS proton antiproton collider 1985 : Nobel Price for S. van der Meer and C. Rubbia 1989 : Start of LEP operation (Z-factory) 1994 : Approval of the LHC by the CERN Council 1996 : Final decision to start the LHC construction 1996 : LEP operation at 100 GeV (W-factory) 2000 : End of LEP operation 2002 : LEP equipment removed 2003 : Start of the LHC installation 2005 : Start of hardware commissioning 2007 : Commissioning with beam planned

R.Schmidt - Villa Olmo Energy and Luminosity l Particle physics requires an accelerator colliding beams with a centre-of-mass energy of, say, 14 TeV (7 TeV per beam) l In order to observe rare events, the luminosity should be [cm -1 s -2 ] l Event rate:

R.Schmidt - Villa Olmo Particle energy and Lorentz Force The force on a charged particle is proportional to the charge, and to the vector product of velocity and magnetic field: Momentum 7000 GeV/c LHC (LEP) radius 2805 m Bending field B = 8.33 Tesla Superconducting magnets Helium cooling at 1.9 K z x s v B F

R.Schmidt - Villa Olmo Luminosity Parameters The objective for the LHC as proton – proton collider is a luminosity of about [cm -1 s -2 ]

R.Schmidt - Villa Olmo Beam beam interaction determines parameters Number of protons N per bunch limited to about f = Hz Beam size σ = 16  m for  = 0.5 m with one bunch N b =1 with N b = 2808 bunches (every 25 ns one bunch) L = [cm -2 s -1 ]

R.Schmidt - Villa Olmo summarising challenges…. Centre-of-mass energy must well exceed 1 TeV in LEP tunnel l Colliding protons, and also heavy ions l Magnetic field of 8.3 T with superconducting magnets l Helium cooling at 1.9 K l Large amount of energy stored in magnets Luminosity of cm -2 s -1 l “Two accelerators” in one tunnel with beam parameters pushed to the extreme – with opposite magnetic dipole field l Many bunches with large amount of energy stored in beams Both together l Unprecedented complexity with magnets powered in 1700 electrical circuits (…and everything that goes with it)

R.Schmidt - Villa Olmo Relevant LHC parameters for 7 TeV (protons) Momentum at collision 7 TeV/c Luminosity cm -2 s -1 Dipole field at 7 TeV 8.33 Tesla Number of bunches 2808 Protons per bunch1.15  Typical beam size µm Beam size at IP 16µm l Energy stored in the magnet system: 10 GJoule l Energy stored in one (of 8) dipole circuit: 1.1 GJoule l Energy stored in one beam: 362 MJoule l Energy to heat and melt one kg of copper: 700 kJ

R.Schmidt - Villa Olmo Livingston type plot: Energy stored magnets and beam based on graph from R.Assmann

R.Schmidt - Villa Olmo Energy stored in magnets Shotput: The energy of one shot (5 kg) at 800 km/hour corresponds to the energy stored in one bunch at 7 TeV. There are 2808 bunches. Airbus 380: The energy of an A380 at 700 km/hour corresponds to the energy stored in the LHC magnet system. shot Energy stored in beam

R.Schmidt - Villa Olmo Protection and Beam Energy A small fraction of beam sufficient for damage Very efficient protection systems throughout the cycle are required A tiny fraction of the beam is sufficient to quench a magnet Very efficient beam cleaning is required Sophisticated beam cleaning with about 50 collimators, each with two jaws, in total about 90 collimators and beam absorbers Collimators are close to the beam (full gap as small as 2.2 mm, for 7 TeV with fully squeezed beams), particles will always touch collimators first !

R.Schmidt - Villa Olmo The LHC accelerator complex

R.Schmidt - Villa Olmo LHC Layout eight arcs (sectors) eight long straight section (about 700 m long) IR6: Beam dumping system IR4: RF + Beam instrumentation IR5:CMS IR1: ATLAS IR8: LHC-B IR2:ALICE Injection IR3: Momentum Cleaning (warm) IR7: Betatron Cleaning (warm) Beam dump blocks

R.Schmidt - Villa Olmo Autumn 2004 The CERN accelerator complex: injectors and transfer High intensity beam from the SPS into LHC at 450 GeV via TI2 and TI8 LHC accelerates from 450 GeV to 7 TeV LEIR CPS SPS Booster LINACS LHC TI8 TI2 Ions protons Extraction Beam 1 Beam 2 Beam size of protons decreases with energy:  2 = 1 / E Beam size large at injection Beam fills vacuum chamber at 450 GeV

R.Schmidt - Villa Olmo Results of TI8 test

R.Schmidt - Villa Olmo TI 8: Beam spot at end of line

R.Schmidt - Villa Olmo LHC accelerator LHC Main Systems Superconducting magnets Cryogenics Vacuum system Powering (industrial use of High Temperature Superconducting material)

R.Schmidt - Villa Olmo main dipoles multipole corrector magnets 392 main quadrupoles corrector magnets Regular arc: Magnets

R.Schmidt - Villa Olmo Regular arc: Cryogenics Supply and recovery of helium with 26 km long cryogenic distribution line Static bath of superfluid helium at 1.9 K in cooling loops of 110 m length Connection via service module and jumper

R.Schmidt - Villa Olmo Insulation vacuum for the cryogenic distribution line Regular arc: Vacuum Insulation vacuum for the magnet cryostats Beam vacuum for Beam 1 + Beam 2

R.Schmidt - Villa Olmo Regular arc: Electronics Along the arc about several thousand electronic crates (radiation tolerant) for: quench protection, power converters for orbit correctors and instrumentation (beam, vacuum + cryogenics)

R.Schmidt - Villa Olmo Dipolmagnets Length about 15 m Magnetic Field 8.3 T Two beam tubes with an opening of 56 mm Dipole magnets for the LHC

R.Schmidt - Villa Olmo Superconducting cable Type 1

R.Schmidt - Villa Olmo Dipole cold masses

R.Schmidt - Villa Olmo First cryodipole lowered on 7 March 2005

R.Schmidt - Villa Olmo Transport in the tunnel with an optical guided vehicle about 1600 magnets to be transported for 20 km at 3 km/hour

R.Schmidt - Villa Olmo Transfer on jacks

R.Schmidt - Villa Olmo Preparation of interconnect

R.Schmidt - Villa Olmo Interconnection of beam tubes Cryogenic distribution line

R.Schmidt - Villa Olmo Cryogenic distribution line

R.Schmidt - Villa Olmo Cryogenic distribution line in the LHC tunnel 30 hours 300 K 0 K

R.Schmidt - Villa Olmo Repair of QRL modules at CERN

R.Schmidt - Villa Olmo Repair of special QRL elements at CERN

R.Schmidt - Villa Olmo Status summary l Magnet production well advanced l Installation in progress, more than 100 cryomagnets have been installed – this must accelerate l Powering system: commissioning started power converters installed and commissioning on short circuits started in tunnel l Cryogenics large part finished and operational (e.g. cryoplants) QRL being installed and partial commissioning started l Other systems (RF, Beam injection and extraction, Beam instrumentation, Collimation, Interlocks, Controls) essentially on schedule l Injector complex ready

R.Schmidt - Villa Olmo Operation and machine protection

R.Schmidt - Villa Olmo Global requirements on the machine l Highest energy proton collisions for ATLAS / CMS Nominal luminosity cm -2 s -1 in points 1 and 5 l Highest energy proton collisions for LHCb Nominal luminosity ~ cm -2 s -1 in point 8 l Proton various energies for ALICE Nominal luminosity ~ cm -2 s -1 in point 2 l Ion various energies for ALICE Nominal luminosity ~ cm -2 s -1 in point 2 ATLAS and CMS will also take data l Proton various energies for TOTEM Proton luminosity running Dedicated operation Dedicated operation

R.Schmidt - Villa Olmo energy ramp preparation and access injection phase coast LHC magnetic cycle L.Bottura 450 GeV 7 TeV start of the ramp

R.Schmidt - Villa Olmo injection phase 12 batches from the SPS (every 20 sec) one batch 216 / 288 bunches LHC magnetic cycle - beam injection L.Bottura 450 GeV 7 TeV beam dump energy ramp coast start of the ramp

R.Schmidt - Villa Olmo Beam lifetime with nominal intensity at 7 TeV Beam lifetime Beam power into equipment (1 beam) Comments 100 h1 kWHealthy operation 10 h10 kWOperation acceptable, collimation must absorb large fraction of beam energy (approximately beam losses = cryogenic cooling power at 1.9 K) 0.2 h500 kWOperation only possibly for short time, collimators must be very efficient 1 min6 MWEquipment or operation failure - operation not possible - beam must be dumped << 1 min> 6 MWBeam must be dumped VERY FAST Failures will be a part of the regular operation and MUST be anticipated

R.Schmidt - Villa Olmo End of data taking in normal operation: Beam Dump l Luminosity lifetime estimated to be approximately 10 h (after 10 hours only 1/3 of initial luminosity) l Beam current somewhat reduced - but not much l Energy per beam still about MJ l Beams are extracted into beam dump blocks l The only component that can stand a loss of the full beam is the beam dump block - all other components would be damaged l At 7 TeV, fast beam loss with an intensity of about 5% of one single “nominal bunch” could damage superconducting coils l In case of failure: beam must go into beam dump block

R.Schmidt - Villa Olmo Schematic layout of beam dump system in IR6 Q5R Q4R Q4L Q5L Beam 2 Beam 1 Beam Dump Block Septum magnet deflecting the extracted beam H-V kicker for painting the beam about 700 m about 500 m Fast kicker magnet

R.Schmidt - Villa Olmo Dumping the LHC beam about 8 m concrete shielding beam absorber (graphite) about 35 cm

R.Schmidt - Villa Olmo Full LHC beam deflected into copper target Target length [cm] vaporisation melting N.Tahir (GSI) et al. Copper target 2 m Energy density [GeV/cm 3 ] on target axis 2808 bunches

R.Schmidt - Villa Olmo SPS experiment: Beam damage at 450 GeV Controlled SPS experiment l 8  protons clear damage l beam size σ x/y = 1.1mm/0.6mm above damage limit l 2  protons below damage limit 25 cm 0.1 % of the full LHC beam 6 cm 8     10 12

R.Schmidt - Villa Olmo Operational margin of a superconducting magnet Bc Tc 9 K Applied Magnetic Field [T] Bc critical field 1.9 K quench with fast loss of ~5 · 10 9 protons quench with fast loss of ~5 · 10 6 protons 8.3 T 0.54 T QUENCH Tc critical temperature This is about 1000 times more critical than for TEVATRON, HERA, RHIC Temperature [K] Applied magnetic field [T]

R.Schmidt - Villa Olmo  ~1.3 mm Beam +/- 3 sigma 56.0 mm Beam in vacuum chamber with beam screen at 7 TeV

R.Schmidt - Villa Olmo Beam+/- 3 sigma 56.0 mm 1 mm +/- 8 sigma = 4.0 mm Example: Setting of collimators at 7 TeV - with luminosity optics Beam must always touch collimators first ! R.Assmanns EURO Collimators at 7 TeV, squeezed optics

R.Schmidt - Villa Olmo The LHC Phase 1 Collimator Vacuum tank with two jaws installed Designed for maximum robustness: Advanced Carbon Composite material for the jaws with water cooling! R.Assmann et al

R.Schmidt - Villa Olmo RF contacts for guiding image currents Beam spot

R.Schmidt - Villa Olmo Proton luminosity running: Parameters Machine parameters l Bunch intensity l Distance between two bunches (number of bunches) l Beta function (beam size) at interaction point Experiments l Will make use of any beam for detector commissioning l Minimize event pileup early on (go to 25 ns as soon as possible) l (My guess…..) Operate safely has priority (300 of cm -2 s -1 = 1 fb -1 ) - From Chamonix XIV - H SM -> 4 l (M Higgs = GeV and GeV) can be discovered with~ 4 fb -1 Some supersymmetry can be discovered at more modest luminosities ~ 1 fb -1 Potential for b-physics right from startup

R.Schmidt - Villa Olmo Proposal for early proton running 1.Pilot physics run with few bunches u No parasitic bunch crossings u Machine de-bugging no crossing angle u 43 bunches, unsqueezed, reduced intensity u Push performance (156 bunches, partial squeeze in 1 and 5, push intensity) 2.75ns operation u Establish multi-bunch operation u Relaxed machine parameters (squeeze and crossing angle) u Push squeeze and crossing angle 3.25ns operation (Phase I collimators + partial beam dump) u Needs scrubbing for higher intensities ( i b > ) 4.25ns operation u Push towards nominal performance R.Bailey

R.Schmidt - Villa Olmo Conclusions

R.Schmidt - Villa Olmo Recalling LHC status and challenges l Enormous amount of equipment l Complexity of the LHC accelerator l New challenges in accelerator physics with LHC beam parameters pushed to the extreme Fabrication of equipment Installation LHC Beam commissioning LHC “hardware” commissioning

R.Schmidt - Villa Olmo Conclusions l The LHC is a global project with the world-wide high-energy physics community devoted to its progress and results l As a project, it is much more complex and diversified than the SPS or LEP or any other large accelerator project constructed to date Machine Advisory Committee, chaired by Prof. M. Tigner, March 2002 l We recognize that the planned schedule is very aggressive, given the complexity and potential for damage involved in the initial phases of operation. l It will be important to understand the performance of the machine protection system, the collimation system and the orbit feedback system as well as cycle repeatability and adequate beta-beat control before proceeding to run with significant stored beam energy. Pressure to take shortcuts must be resisted. Machine Advisory Committee, chaired by Prof. M. Tigner, June 2005

R.Schmidt - Villa Olmo Is everything always going smoothly? Not really…. I am convinced that for a project such as the LHC, considering the complexity uniqueness novelty difficulties will always be encountered. However, it is important that such difficulties are identified, addressed, and mastered. This is required to make a project success

R.Schmidt - Villa Olmo Acknowledgement The LHC accelerator is being realised by CERN in collaboration with institutes from many countries over a period of more than 20 years Main contribution come from the USA, Russia, India, Canada, special contributions from France and Switzerland Industry plays a major role in the construction of the LHC Thanks for the material from: R.Assmann, R.Bailey, F.Bordry, L.Bottura, L.Bruno, L.Evans, B.Goddard, M.Gyr

R.Schmidt - Villa Olmo Some references Accelerator physics l Proceedings of CERN ACCELERATOR SCHOOL (CAS), In particular: 5th General CERN Accelerator School, CERN 94-01, 26 January 1994, 2 Volumes, edited by S.Turner Superconducting magnets / cryogenics l Superconducting Accelerator Magnets, K.H.Mess, P.Schmüser, S.Wolff, World Scientific 1996 l Superconducting Magnets, M.Wilson, Oxford Press l Superconducting Magnets for Accelerators and Detectors, L.Rossi, CERN-AT MAS (2003) LHC l Technological challenges for the LHC, CERN Academic Training, 5 Lectures, March 2003 (CERN WEB site) l Beam Physics at LHC, L.Evans, CERN-LHC Project Report 635, 2003 l Status of LHC, R.Schmidt, CERN-LHC Project Report 569, 2003 l...collimation system.., R.Assmann et al., CERN-LHC Project Report 640, 2003 l LHC Design Report 2003

R.Schmidt - Villa Olmo Reserve Slides

R.Schmidt - Villa Olmo Conclusions l The LHC is a global project with the world-wide high- energy physics community devoted to its progress and results l As a project, it is much more complex and diversified than the SPS or LEP or any other large accelerator project constructed to date Machine Advisory Committee, chaired by Prof. M. Tigner, March 2002 l No one has any doubt that it will be a great challenge for both machine to reach design luminosity and for the detectors to swallow it. l However, we have a competent and experienced team, and 30 years of accumulated knowledge from previous CERN projects has been put into the LHC design L.Evans

R.Schmidt - Villa Olmo Beam on Beam Dump Block about 35 cm M.Gyr initial transverse beam dimension in the LHC about 1 mm beam is blown up due to long distance to beam dump block additional blow up due to fast dilution kickers: painting of beam on beam dump block beam impact within less than 0.1 ms

R.Schmidt - Villa Olmo L.Bruno: Thermo-Mechanical Analysis with ANSYS Temperature of beam dump block at 80 cm inside up to C

R.Schmidt - Villa Olmo High luminosity running l Eventual goal: luminosity of cm -2 s -1 (ATLAS & CMS) Nominal settings Beam energy (TeV)7.0 Number of particles per bunch Number of bunches per beam2808 Crossing angle (  rad) 285 Nomalised transverse emittance (  m rad) 3.75 Bunch length (cm)7.55 Beta function at IP 1, 2, 5, 8 (m)0.55,10,0.55,10 Related parameters Luminosity in IP 1 & 5 (cm -2 s -1 )10 34 Luminosity in IP 2 & 8 (cm -2 s -1 )~ Transverse beam size at IP 1 & 5 (  m) 16.7 Transverse beam size at IP 2 & 8 (  m) 70.9 Stored energy per beam (MJ)362

R.Schmidt - Villa Olmo Regular (very healthy) operation Assuming that the beams are colliding at 7 TeV Single beam lifetime larger than 100 hours….. Collision of beams with a luminosity of cm -2 s -1 lifetime of the beam can be be dominated by collisions 10 9 protons / second lost per beam / per experiment (in IR 1 and IR 5 - high luminosity insertions)

R.Schmidt - Villa Olmo Beam losses into material l Proton losses lead to particle cascades in materials l The energy deposition leads to a temperature increase l For the maximum energy deposition as a function of material there is no straightforward expression l Programs such as FLUKA are being used for the calculation of the energy deposition Magnets could quench….. beam lost - re-establish condition will take hours The material could be damaged….. melting losing their performance (mechanical strength) Repair could take several weeks

R.Schmidt - Villa Olmo Quench - transition from superconducting state to normalconducting state Quenches are initiated by an energy in the order of mJ (corresponds to the energy of 1000 protons at 7 TeV) l Movement of the superconductor by several  m (friction and heat dissipation) l Beam losses l Failure in cooling To limit the temperature increase after a quench (in 1s to 5000 K) l The quench has to be detected l The energy is distributed in the magnet by force-quenching the coils using quench heaters l The magnet current has to be switched off within << 1 second

R.Schmidt - Villa Olmo is a lot of bunches per beam l Filling scheme requires 12 SPS cycles per beam Each with 2,3 or 4 batches of 72 bunches l Crossing angle needed l Emittance conservation with protons per bunch through Injecting Ramping Squeezing to 0.55m l This is going to take us a little while !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

R.Schmidt - Villa Olmo Cryodipole overview

R.Schmidt - Villa Olmo Density change in target after impact of 100 bunches Energy deposition calculations using FLUKA Numerical simulations of the hydrodynamic and thermodynamic response of the target with two- dimensional hydrodynamic computer code Target radial coordinate [cm] radial copper solid state N.Tahir (GSI) et al. 100 bunches – target density reduced to 10%