Much of this material comes from lectures given by Philippe Lebrun (head of CERN's Accelerator Technology Department), at SUSSP, Aug

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4 Much of this material comes from lectures given by Philippe Lebrun (head of CERN's Accelerator Technology Department), at SUSSP, Aug

5 * + Performance RF Vacuum Magnets* Cryogenics Outlook 2% 2% 3% 15% 1% 1% 3% 2% 3% 2% 12% 54% Magnets Cryogenics Beam dump Radio-frequency Vacuum Power converters Beam instrumentation Civil Engineering Cooling & ventilation Power distribution Infrastructure & services Installation & coordination

6 * Performance RF Vacuum Magnets* Cryogenics Outlook Topics NOT covered ATLAS CMS LHCb ALICE LHCf, TOTEM Testable BSM theories at LHC Possible future SASS talks? (hint, hint )

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9 / Preliminary conceptual studies 1984 First magnet models 1988 Start structured R&D program 1990 Approval by CERN Council 1994 Industrialization of series production DUP & start civil works 1998 Adjudication of main procurement contracts Start installation in tunnel 2003 Cryomagnet installation in tunnel Functional test of first sector 2007 Commissioning with beam 2008 Magnet quench Sep Planned operation at half-energy Nov. 2009

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12 " 1 B E! F = e ( E + v B ) e R v 0 & p = e B R [ GeV / c] 0. B [ T ] R[ m] p 3 " $ # % / '" ())*+ *$+, -.

13 1 2 " Normal conducting Superconducting LHC 7 Bending field [T] RHIC HERA proton ring Tevatron 2 1 ISR SppS Circumference [km]

14 3 1.E+35 1.E+34 x 7 LHC Luminosity [cm -2.s -1 ] 1.E+33 1.E+32 1.E+31 ISR LEP2 LEP1 HERA SppS TeVatron x E Center-of-mass energy [GeV]

15 1+ + L = Nb nb frev γ * 4 π ε β n /2 F / 3 1! 4 To maximize luminosity increase bunch number, bunch population reduce emittance, beta function at collision point cross at small angle

16 4 1 Circumference 26.7 km Beam energy at collision 7 TeV Collision energy, Pb ions 2.76 TeV/u Beam energy at injection 0.45 TeV Stored energy per beam 362 MJ Stored energy in magnets 11 GJ Dipole field at 7 TeV 8.33 T Radiated power per beam 3.6 kw Operating temperature 1.9 K Beam duration ~10 hrs. Power consumption 120 MW Annual operating cost 19 million Euros

17 Energy stored in circulating beam E beam = m 0 c 2 γ N b n b With 2808 bunches of protons at 7 TeV, E beam = 362 MJ, equivalent to 80 kg TNT! L = N f 1 N b F F E = f 2 rev * 4 π m π m c ε β b rev 2 * beam 0 c ε n β 4 0 n E beam 5+

18 1 Luminosity will decay with time due to degradation of beam intensity and emittance, by several processes intra-beam scattering, i.e. multiple Coulomb scattering between particles in the same bunch nuclear scattering of particles by residual gas molecules the collisions themselves Overall N total L 1 τ L = 1 τ IBS τ Ntotal τ nuclear = k L σ gas nuclear + τ 1 total 6+,(( 6-

19 % Number of bunches 2808 Protons per bunch 1.15 x Nominal bunch spacing ns = 7 m Bunch length few cm Bunch cross-section 1 mm Bunch cross-section at IP 16 m Collisions per crossing 20 Collisions per second 600 million Luminosity cm -2 s -1 Beam current 0.58 A Data recorded per second 700 MB Data recorded per year 15 PB

20 5 6 ) 8 cavities per beam One klystron per cavity 400 MHz Superconducting (niobium sputtering on copper) for small energy losses Operate at 4.5 K 16 MV in coast; 8 MV in injection Field: 5 MV/m Beam separation increased to 420 mm (normally at 194 mm) Power supplied to beams: 275 kw/beam

21 7 ) ) 3 vacuum systems Beampipe: <10-10 mbar (1/10 pressure on moon). Insulation for cryomagnets (~10-6 mbar): largest volume (~9000 m 3 ) Insulation for He distribution (~10-6 mbar)

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23 7 1 " Without beam 8 P = With beam 0:: P = Q S Q + η Γ S 9 0 0:: 4 0 "

24 ) 1 Dominated by nuclear scattering of protons on residual gas Lifetime of 100 h required to Limit decay of beam intensity Reduce energy deposited by scattered protons to ~ 5 30 mw/m 1 1 dn = = vσ i ni N dt τ gas i Partial pressure P i = n i k B T 0

25 ) 1 Gas species Nuclear scattering cross-section [mbarn] Gas density for 100 h lifetime [m -3 ] Pressure at 5 K for 100 h lifetime [Pa] H E E-8 He E E-8 CH E E-8 H 2 O E E-8 CO E E-9 CO E E-9

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29 ) ) 9300 total magnets dipole magnets, 14.3 meters long, 35 tons Tesla (@ 7 TeV) ~200,000x Earth's magnetic field NbTi cables; superconducting below 10 K 1.9 Kelvin A

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31 Superconducting magnets enable to contain electrical power consumption through two independent effects Higher magnetic field smaller circumference ; No dissipation lower power (refrigeration) per unit length (* <= 8 + ()* <1+*= 8 + >: - -1:?:.>: - ).1: /

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33 1 B >C B ( r) ds = µ 0 I( r) B B ( r) = µ 0 J r 2

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35 " *,, 2 D θe & + + D!E D E

36 6 8 B y F 3 G 4:4I. + ib x = B % FG 1 ( bn + ian) n= 1 x + iy r ref n 1 & D E >2F G + 8 H, F G +, + *

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39 " km of cable, made of 36 twisted 15-mm strands 250,000 km of strands, made of 6400 filaments (7 micron diameter) filaments laid end to end would stretch from earth to Sun and back 5 times

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46 ; < '!! / ) Number of Cryo-dipoles not reached Number of quenches to reach 8.33T

47 1 " H V beam waist silver mid-cell silver silver mid-cell silver Definition of geometry classes Distribution of as-built MB s

48 " π b3 distribution in sector 7-8 Effect of flip-flop pairing Effect of π-pairing

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54 1.9 K: colder than outer space Largest cryogenic system in the world 150 kw refrigerators at 4.5 K 20 kw refrigerators at 1.9 K 5 cryogenic islands Cooling process takes ~weeks Cool to 4.5 K (using t LN 2 & refrigerator turbines) Fill magnets with liquid He Final cool to 1.9 K Total of 120 t of He needed

55 Temperature difference [K] Tevatron LEP2 Tore Supra Pressurised He II Saturated LHe II He I UNK HERA TESLA SSC (HEB) SSC (main Ring) Distance [km] LHC Need leak-tight pipe junctions

56 %% Superfluid below 2.17 K Low effective viscosity 100 times lower than water at normal boiling point Very high specific heat 10 5 times that of the conductor by unit mass 2x10 3 times that of conductor by unit volume Very high thermal conductivity 10 3 times that of OFHC copper, cryogenic grade Peaking at 1.9 K Still, insufficient for transporting heat over large distances across small temperature gradients

57 : 1 ) " '"6K * -N<++ = ) 6.?: - H.%?: (N 77N '-N)% & 6?: - H?:

58 " = ', *H #:γ" I #,µ@ + * + <D2E= I op T LHe T * 6(7N 52 6@: ) # L(%@ # + )L%@ H [J/(m 3 K)] 1.E+05 1.E+05 1.E+05 8.E+04 6.E+04 4.E+04 Volumetric Specific Heat Al NbTi Cu G10 2.E+04 0.E T [K]

59 ; 9 days after startup in Sep. 2009, an electrical connection between 2 magnets melted Damaged liquid He plumbing, causing a temp. rise of ~100 K, 100 magnets quenched Large amounts of He vaporized, too fast for release valves Release of pressure displaced magnets by ~.5 m 53 magnets were damaged and had to be replaced

60 > LHC ~$4.5 billion Hubble Space Telescope ~$4.5-6 billion Nimitz class aircraft carrier ~$4.5 billion 2 B-2 bombers ~$4.2 billion *Cost estimates from Wikipedia

61 LHC the Guide, CERN-Brochure Eng (~60 pp.). Abridged LHC Design Report (~160 pp.): 2008 JINST 3 S08001 Full LHC Design Report (~600 pp.): CERN v1.

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