FermilabFermilab’’ss TevatronTevatron && LargeLarge HadronHadron ColliderCollider (LHC)(LHC) Teruki Kamon PHYS 627 Taken from slides by Ron Moore, Paul Derwent, Mike Syphers (FNAL) (Apr 2005) Modified/updated by Teruki Kamon for PHYS 627 Hadron Collisions at the Tevatron and the LHC 1 AA littlelittle bitbit ofof EinsteinEinstein…… Recall the well-known equation: E = mc 2 Measure energy in “electron volts” = eV (1 eV ≈ 1.6 x 10−19 Joule) 2 Measure mass in units of eV/c … (1 eV/c2 ≈ 1.78 x 10−36 kg) …but often use units where c ≡ 1, so mass can also be measured in eV For a moving particle: 1 v 2 2 2 2 γ = β ≡ E = (mc ) + ( pc) = γ mc 1 − β 2 c 2 2 Total Energy = Rest Energy + Kinetic Energy E = mc + (γ − 1 )mc Ultra-relativistic: γ >> 1 can neglect rest mass Hadron Collisions at the Tevatron and the LHC 2 FixedFixed TargetTarget vs.vs. CollidersColliders w/ow/o calculuscalculus Hadron Collisions at the Tevatron and the LHC 3 FixedFixed TargetTarget vs.vs. CollidersColliders w/w/ calculuscalculus Fixed Target Center of Mass Energy Energy E s = 2mE ultrarelativistic limit Head-On Collision Energy E Energy E s = 2E Compare protons @ 1 TeV: Fixed Target: ECM = 43 GeV Collider: ECM = 2000 GeV Big advantage for colliders! ⇒ Most efficient use of beam energy for physics! Challenge to get a high collision rate to look for interesting (rare) processes Fixed target still essential for secondary beams: antiprotons, kaons, µ’s, ν’s Hadron Collisions at the Tevatron and the LHC 4 Hadron Collisions at the Tevatron and the LHC 5 σ int σ int σ int A 3.46 x 109 crossings Skip Hadron Collisions at the Tevatron and the LHC 6 LuminosityLuminosity N N L = f 1 2 Luminosity is measure of the collision rate in a collider 4πσ 2 − 2 −1 Units are cm s f is collision frequency 32 − 2 − 1 × Peak luminosity ~ 1.2 10 cm s N 1, N 2 are # particles in each beam 32 − 2 − 1 Goal ~ 4.0 ×10 cm s σ is beam size −24 2 32 − 2 − 1 − 1 10 cm = 1 barn; 10 cm s = 360 nb /hr To reach higher luminosity… More beam May be hard…Tevatron needs more antiprotons Higher collision frequency (more bunches) Not for Tevatron – will keep using 36 bunches of protons and antiprotons Smaller beam Tevatron beams are ~30 µm wide at interaction points Linear colliders have nm size beams All can be hard to achieve due to instabilities that may develop Want high luminosity to study rare processes Luminosity × Cross Section = Event Rate 32 −2 − 1 e.g., 1 × 10 cm s × 10 pb = 3.6 events/hr Hadron Collisions at the Tevatron and the LHC 7 ModelModel ofof AcceleratorAccelerator Accelerating device + magnetic field to bring it back to accelerate again += Hadron Collisions at the Tevatron and the LHC 8 Hadron Collisions at the Tevatron and the LHC 9 WhereWhere isis thethe FermilabFermilab?? Hadron Collisions at the Tevatron and the LHC 10 Looking Down on the Fermilab Accelerator Complex ~5 mi. CDF D0 Hadron Collisions at the Tevatron and the LHC 11 CloselyClosely LookingLooking DownDown onon thethe FermilabFermilab Wilson Hall Tevatron Main 1 km Injector Hadron Collisions at the Tevatron and the LHC 12 NuMI (120 GeV protons) MiniBoone (8 GeV) 1 6 2 3 7 5 4 9 Accelerator Highest Energy Cockroft Walton 750 keV 8 Linac 400 Mev 10 Booster 8 GeV Main injector 150 GeV TEVATRON 980 GeV MachineMachine EnergiesEnergies ((cc == 1)1) Comparing relativistic β, γ for electrons and protons at various energies… electron proton rest mass 511 keV 938 MeV Machine KE βγβγ Cockroft-Walton 750 keV 0.926794588 2.47 0.707389304 1.00 FNAL Linac 400 MeV 0.999999186 784 0.818829208 1.43 FNAL Booster 8 GeV 0.999999998 15657 0.994538328 9.53 Main Injector 150 GeV 1 293543 0.999980691 161 ILC 500 GeV 1 978475 0.999998247 534 Tevatron 980 GeV 1 1.918E+06 0.999999543 1046 LHC 7 TeV 1 1.761E+07 0.999999995 9596 VLHC? 100 TeV 1 1.957E+08 1 106611 1 keV = 103 eV 1 MeV = 106 eV 1 GeV = 109 eV 1 TeV = 1012 eV Mass of top quark ≈ 175 GeV Hadron Collisions at the Tevatron and the LHC 14 HiHi--riserise BuildingBuilding •25 keV H− ion source •750 keV Cockcroft- Walton accelerator Hadron Collisions at the Tevatron and the LHC 15 CockcroftCockcroft--WaltonWalton •25 keV H− ion source •750 keV Cockcroft-Walton accelerator Hadron Collisions at the Tevatron and the LHC 16 LinacLinac Accelerate H− ions to 400 MeV − 116 MeV Alvarez linac (201.25MHz) H ions 400 MeV side-coupled cavity linac (805 MHz) Hadron Collisions at the Tevatron and the LHC 17 BoosterBooster Booster: 8 GeV Synchrotron Runs at 15 Hz Stripper foil at injection removes electrons from H− ions Accelerates protons from 400 MeV to 8 GeV Most protons (>75%) going through Booster are delivered to MiniBoone (eventually NuMI) Hadron Collisions at the Tevatron and the LHC 18 Main Injector & Recycler Ring Recycler Main Injector Hadron Collisions at the Tevatron and the LHC 19 MainMain InjectorInjector (MI)(MI) Replaced Main Ring (formerly in Tevaron tunnel) Higher repetition rate for stacking pbars Simultaneous stacking and fixed target running Many operating modes 12 Pbar production: ~ 6-7 x 10 120-GeV protons to pbar target “Slip-stacking” – merge two booster batches of beam on 1 MI ramp cycle “Tevatron protons/pbars”: Accelerate 8 GeV to 150 GeV 9 Coalesce 7-9 proton bunches at 90% eff into “270-300 x 10 proton” bunch 9 Coalesce 5-7 pbar bunches at 75-90% eff into “20-80 x 10 antiproton” bunch Transfer 8-GeV protons/pbars to the Recycler Provide protons for neutrino production 8-GeV protons for MiniBoone 120-GeV protons for NuMI 120-GeV protons to Switchyard (fixed target area) Hadron Collisions at the Tevatron and the LHC 20 DebuncherDebuncher && AccemulatorAccemulator Debuncher Two rings Accumulator Hadron Collisions at the Tevatron and the LHC 21 PbarPbar (Antiproton)(Antiproton) SourceSource (1) > 6 x 1012 120-GeV protons per pulse strike Ni target every 2-3 sec; (2) Li lens (740 Tesla/m) collects negative secondaries; (3) Pulsed dipole “PMAG” bends pbars down AP-2 line to Debuncher ε≈(14-18) x 10−6 pbars/proton on target Pbars “debunched”, cooled briefly in Debuncher prior to Accumulator Hadron Collisions at the Tevatron and the LHC 22 PbarPbar (Antiproton)(Antiproton) SourceSource Stack rate = 6-14 mA/hr Depending on stack size; Limited by stochastic cooling systems in Accumulator Transverse beam size increases linearly with stack size - That’s a drawback… In a really good 24 hour period, nearly 200 x 1010 pbars can be accumulated. −12 −24 Pbar Production Rate = 3.3 x 10 g/day (Mpbar ≈ 1.67 x 10 g) 800 million years to make 1 g of antimatter! Hadron Collisions at the Tevatron and the LHC 23 TevatronTevatron OverviewOverview Proton-pbar collisions (Ebeam = 980 GeV) Revolution time ~ 21 µs Virtually all of the Tevatron magnets are superconducting (Cooled by liquid helium, operate at 4 K) 150 GeV beams are injected from MI Protons injected from P1 line at F17; Pbars injected from A1 line at E48 36 bunches of proton and pbars circulate in same beam pipe, but separated by “electrostatic separators” 3 trains of 12 bunches with 396 ns separation (see the next page) 2 low β (small beam size) intersection points (CDF and D0) 8 RF cavities (near F0) to keep beam in bucket, acceleration 1113 RF buckets (53.1 MHz ⇒ 18.8 ns bucket length) Hadron Collisions at the Tevatron and the LHC 24 ProtonProton BunchBunch PositionsPositions 3 trains of 12 bunches with 396 ns separation P12 P13 P1 P24 P25 P36 Hadron Collisions at the Tevatron and the LHC 25 ProtonsProtons andand PbarsPbars atat HEPHEP Proton Collide Collide bunches @ CDF @ D0 P1-P12 A25-A36 A13-A24 A P13-P24 A1-A12 A25-A36 2 4~ P25-P36 A13-A24 A1-A12 P1 3 P25~P36 Hadron Collisions at the Tevatron and the LHC 26 ProtonProton--PbarPbar CollisionCollision PointPoint Hadron Collisions at the Tevatron and the LHC 27 First Collisions at the Tevatron Run 493 Event 11 Run 493 Event 15 October 13, 1985 Hadron Collisions at the Tevatron and the LHC 28 LargeLarge HadronHadron ColliderCollider HighlightsHighlights ~27km circumference 1232 bends Main bends are 14.3 meters long The strength of each magnet is 8.33 Tesla Huge synchrotron radiation loss. SynchrotronSynchrotron RadiationRadiation Accelerated charges produce radiation. r e ⎡ nr × (nr × β&)⎤ Useful equations for ideal conditions in SI E a = ⎢ ⎥ c R ⎣ ⎦ ret qvB v = r c r r c r 2 & S = E × B = E nr γm 4π 4π a 2 2 dP c r 2 e 2 e 2 = RE = nr × (nr × β&) = vr& sin 2 Θ dΩ 4π a 4πc 4πc 3 2 2 e 2 P = vr& 3 c 3 Above we integrated over the angle Θ, and below switched to more familiar units SI 2 r 2 q ⎛ dp ⎞ 4 1 dE dpr = ⎜ ⎟ ⎛ q ⎞ 2 2 Pγ 2 3 From here were can get if << 6π m c dt Pγ ∝ ⎜ ⎟ U B ε ο ⎝ ⎠ ⎝ m ⎠ c dτ dτ Go to, for example, Jackson’s Classical Electrodynamics book, find more convenient expression in terms of v, ρ, γ Hadron Collisions at the Tevatron and the LHC 31.