Accelerators LISHEP Lecture I Oliver Brning CERN - PDF document

Accelerators LISHEP Lecture I Oliver Brüning CERN http://bruening.home.cern.ch/bruening

Particle Accelerators Physics of Accelerators: High power RF waves Cryogenics Super conductivity Magnet design + construction Vacuum surface science, solid state physics, electro dynamics, engeneering, computer science Physics of Particle Beams: Single particle dynamics Collective effects Two beam effects classical and quantum mechanics, non-linear dynamics, relativity, electro dynamics, computer science

Overview ) I Motivation & Sources + Linear Accelerators II ) Circular Accelerators + main limitations III ) Challanges for the LHC IV ) Other Accelerator Projects & Applications

Overview and History: • S. Weinberg, ’The Discovery of Subatomic Particles’, Scientific American Library, 1983. (ISBN 0-7167-1488-4 or 0-7167-1489-2 [pbk]) (539.12 WEI) • C. Pellegrini, ’The Development of Colliders’, AIP Press, 1995. (ISBN 1-56396-349-3) (93:621.384 PEL) • P. Waloschek, ’The Infancy of Particle Accelerators’, DESY 94-039, 1994. • R. Carrigan and W.P. Trower, ’Particles and Forces - At the Heart of the Matter’, Read- ings from Scientific American, W.H. Freeman and Company, 1990. • Leon Lederman, ’The God Particle’, Delta books 1994 • Lillian Hoddeson (editor), ’The rise of the standard model: particle physics in the 1960s and 1970s’, Cambridge University Press, 1997 • S. Weinberg, ’Reflections on Big Science’, MIT Press, 1967 (5(04) WEI) Introduction to Particle Accelerator Physics: • Mario Conte and William McKay, ’An Introduction to the Physics of Particle Accelera- tors’, Word Scientific, 1991 • H.Wiedemann, ’Particle Accelerator Physics’, Springer Verlag, 1993. • CERN Accelerator School, General Accelerator Physics Course, CERN Report 85-19, 1985. • CERN Accelerator School, Second General Accelerator Physics Course, CERN Report 87-10, 1987. • CERN Accelerator School, Fourth General Accelerator Physics Course, CERN Report 91-04, 1991. • M. Sands, ’The Physics of Electron Storage Rings’, SLAC-121, 1970. • E.D. Courant and H.S. Snyder, ’Theory of the Alternating-Gradient Synchrotron’, Annals of Physics 3 , 1-48 (1958). • CERN Accelerator School, RF Engeneering for Particle Accelerators, CERN Report 92- 03, 1992. • CERN Accelerator School, 50 Years of Synchrotrons, CERN Report 97-04, 1997. • E.J.N. Wilson, Accelerators for the Twenty-First Century - A Review, CERN Report 90-05, 1990.

Special Topics and Detailed Information: • J.D. Jackson, ’Calssical Electrodynamics’, Wiley, New York, 1975. • Lichtenberg and Lieberman, ’Regular and Stochastic Motion’, Applied Mathematical Sci- ences 38, Springer Verlag. • A.W. Chao, ’Physics of Collective Beam Instabilities in High Energy Accelerators’, Wiley, New York 1993. • M. Diens, M. Month and S. Turner, ’Frontiers of Particle Beams: Intensity Limitations’, Springer-Verlag 1992, (ISBN 3-540-55250-2 or 0-387-55250-2) (Hilton Head Island 1990) ’Physics of Collective Beam Instabilities in High Energy Accelerators’, Wiley, New York 1993. • R.A. Carrigan, F.R. Huson and M. Month, ’The State of Particle Accelerators and High Energy Physics’, American Institute of Physics New Yorkm 1982, (ISBN 0-88318-191-6) (AIP 92 1981) ’Physics of Collective Beam Instabilities in High Energy Accelerators’, Wiley, New York 1993.

I) Motivation & Sources Linear Accelerators Motivation Particle Sources Acceleration Concepts: Equations and Units DC Acceleration RF Acceleration Electro−Magnetic Waves & Boundary Conditions Summary

Search for Elementary Particles Stage I: Nuclear Physics Chronology: Dalton Atom 1803: M & P Curie Atoms can decay 1896: Electron Thomson 1896: + Nucleus Rutherford 1906: Electron α + N O + H+ 1911: Rutherford Disintegration of Nuclei! Particle Accelerators

NP 1906: discovery of the electron

Rutherford 1906 − 1911: experimental evidence of atom structure NP for N. Bohr in 1922

Stage II: Particle Physics Chronology (Theory): 2 1905: Einstein E = mc 1930: Dirac Antimatter π 1935: - Meson Yukawa Chronology (Experiments): (Cosmic Rays) + Anderson 1932: e µ 1937: Anderson p - π } ? Accelerators

+ 1932: Anderson e (NP 1936: cosmic rays) ionizing particle

bubble chamber particle Κ

− e : Particle Sources: − e + − Cathode Rays

Particle Sources: ions + − H + e H + Example: − 2 e 2 2 + + − + + e p + − H + e H H 2 + − H + e H + 2 e − Antimatter: Pair Production

Acceleration Concepts Lorentz Force: dp ( ) + = Q E v x B * dt Energy gain only due to E field! Scalar and Vector Potential: 1 e A φ - -grad E = B = rot A c t e Electrostatic fields (A = 0) φ Time varying fields ( = 0)

Units Energy Gain: 1 eV 1 Volt E e − −19 (1.6 * 10 J) Common Units: keV, MeV, GeV, TeV 12 ) 3 6 9 ( 10 , 10 , 10 , 10 Total Particle Energy: 2 γ Relativity: E = mc ; m = * m 0 2 γ = 1/ 1 − ; β = v/c β −31 m = 9.11*10 kg; 0.51 MeV Electron: 0 −27 m = 1.67*10 kg; 0.94 GeV Proton: 0

Electrostatic Fields ion source High Voltage Unit: + acceleration high voltage unit tube V = 200 kV max - target Cascade Generator: 2U 4U 6U 0 o o o diodes ω U = U sin t o capacitors 1928: Cockroft + Walton 800kV p + Li 2 He 1932: 700kV (p) (Nobel Prize 1951)

High Voltage Unit at CERN:

Cascade Generator at CERN:

Van de Graaf Generator Single Unit: top terminal + + 10 MV + + + + + charge collector + ion + + source + + + + charge + + + + conveyor + belt + evacuated + + acceleration + channel 50 kV dc spraycomb experiment spectrometer magnet V = 10 MVolt max

Van de Graaf Generator Tuve 1935:

Van de Graaf Generator Tandem generator: experiment pressure tank negative + high voltage terminal + ion Source - - - - + + + + + + + + - - - - - + - spraycomb striping foil 50 kV or gas dc charge conveyor belt V = 25 MVolt max

Van de Graaf Generator Daresbury: 42 m high 20 MVolt 2 * Tandem Van de Graaf in BNL 1970

Time Varying Fields Linear Acceleration: beam E E E beam E−Field in the wrong direction! bunched beam requires shielding and timing between ´v´ and freq! long accelerator structure requires energy to move charges on capacitor plates!

Drift Tubes Ising 1924: V AC Voltage: t Symmetric line: + BEAM + + − − + + + − − + + − l = v T/2 part 1928: demonstrated by Wideroe 1MHz, 25kV oscillator 50kV potassium ions Lawrance: 1.3MV mercury ions with 48kV

Drift Tubes But: support tubes have capacitive impedance f < 7MHz operation limited to low frequencies l = v T/2 part + BEAM + + − − + + + − − + + − implies large structures for v = c! f = 7MHz −> l = 21 meter (for v = c)! only efficient for low energetic particles high energetic particles require higher frequencies find a structure with passive supports

Resonance Structures e A E = − 1 e E rot B = µε c e c e t t E capacitor beam AC generator Resonator: 2 µ N A L = 0 capacitor l C = ε A 0 coil d B beam E beam cavity cavity f; Q; R

LEP Cavity TM mode with 352 MHz; 1.5 MV/m 010

LEP Cavity

Resonance Structures Cavity Resonator: beam axis H E efficient use of energy exact dimensions determined by Maxwell Equations with boundary conditions

Time Varying Fields Maxwell Equations without Sources 1 B e Δ Δ x E + = 0 b) * E = 0 a) c t e µε e E Δ Δ x B − = 0 d) * B = 0 c) c t e d) and Rotation on b) Δ Δ Δ Δ Δ plus: x ( x V ) = ( V ) − V Wave equation: 2 2 c 2 c 2 2 2 e B Δ E e Δ t 2 = B = E µε µε 2 e t e

Time Varying Fields Plane Electro Magnetic Wave: ω ω ik n x − t ik n x − t B = B e E = E e 0 0 k = 2 π µε B = n x E 0 0 λ No acceleration in the direction of propagation!

Wave Guide Boundary Conditions option of two field configurations Transverse Electric Waves (TE): e B E = 0 everywhere; Boundary condition: = 0 z n e s E H H λ 2 immage charges Transverse Magnetic Waves (TM): Boundary condition: E = 0 B = 0 everywhere; z n s E H λ 2 wall currents displacement currents

Boundary Conditions I Transverse Electric Waves (TE): e B E = 0 everywhere; Boundary condition: = 0 z n e s Transverse Magnetic Waves (TM): B = 0 everywhere; Boundary condition: E = 0 z n s TM 01

Solutions for TM Waves Cylindrical Coordinates: Maxwell Equations: Example TM−mode: (Chapter 8 in Jackson: Classical Electrodynamics) mode frequency: