Accelerators

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Accelerators

• Mark Mandelkern

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For producing beams of energetic particles

• Protons, antiprotons and light ions
• heavy ions
• electrons and positrons
• (secondary) neutral beams (photons, neutrons,
  neutrinos)

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Some accelerator applications

• particle and nuclear physics
• synchrotron radiation
• materials science, biology
• medical radiation therapy
• isotope production
• plasma heating
• high energy X-ray production
• non-destructive testing, food sterilization

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Accelerators in particle physics

• probe small-scale structure
• l h/p197 10-13 cm /p(MeV/c)
• electrons, positrons
• Pointlike (also neutrinos), no strong
  interactions
• costly to accelerate (synchrotron radiation)
• protons and antiprotons
• complicated structures make interpretation
  difficult
• easier to accelerate to ultra-high energies

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Accelerator types

• electrostatic
• battery, lightning, van de Graff, Pellatron to
  about 30 MeV for nuclear physics and isotope
  production
• cascade
• Cockcroft-Walton to several MeV cheap for
  X-ray sources and injectors
• Linear
• RFQ
• drift-tube(Wideroe, Alvarez)preaccelerators,
  LAMPF
• Waveguideelectrons only(SLAC, NLC)

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Pelletron
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Van de Graff
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Cockcroft-Walton principle
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ISIS Cockcroft-Walton
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Wideroe Linac
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Alvarez Linac
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Radiofrequency Quadrupole RFQ
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SLAC Linac
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SLAC Waveguide
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Phase Stability
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Circular Accelerators

• betatron
• electrons only, cheap, portable, to 500 MeV
• cyclotron
• Protons to 500 MeV (TRIUMF, PSI)
• Synchrotron
• 100 GeV electrons (LEP)
• 1 TeV protons and antiprotons (FNAL)
• 7 TeV protons (LHC)

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Cyclotron animation
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First cyclotron
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TRIUMF
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Strong focusing principle
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Strong focusing animation
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HEP Accelerator Systems

• FNAL Tevatron(1 TeV p)
• CW(750 keV)LinacBooster(8 GeV)Main
  Injector(120 GeV) Tevatron Ring
• CERN SPS/LEP(400 GeV p/100 GeV e-)
• RFQ (750 keV)Linac (50 MeV)PS(28 GeV)SPSLEP

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FNAL Tevatron Tunnel
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Synchrotron radiation

• W(e2/3e0)(g4b3/R) loss per turn
• Ec(hc/2p)(3g3/2R) peak energy
• gE/mc2
• LEP 100 GeV/beam R4.9km W3 GeV Ec 90
  keV(hard X-ray) 288 SC RF cavities
• Tevatron E1 TeV R1.1km W 10 eV Ec0.4 eV
• LHC E7 TeV R4.9 kmW5 keV, Ec27 eV

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Colliders

• Circular
• e- e below 10 GeV (BEPS/PEP-2/KEKB)
• 1 TeV p/1 TeV pbar (Tevatron-FNAL),
• 27.5 GeV e-/920 GeV p (HERA-DESY)
• 105 GeV e-/105 GeV e (LEP-CERN)
• 7 TeV p/7TeV p (LHC-CERN)
• Linear
• 50 GeV e-/50 GeV e (SLC-SLAC)
• 1 TeV e-/1 TeV e (NLC-?)

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Why Colliders?

• Fixed target (pp)
• Ecm2mb2mt22Ebmt
• Eb1 TeV mbmt0.938 GeV Ecm43.3 GeV
• Symmetrical Collider
• EcmEbEt
• EbEt 1 TeV Ecm2 TeV

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How Colliders?

• Event Rate Ls
• Lf n1n2/(4psxsy)
• n1 n2 particles per bunch
• sx,sy rms horizontal (vertical) beam profile
• Thus intense bunched beams with tiny beam spots
  at the interaction points

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LEP
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LHC
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SLC/NLC