Transcript Accelerators - University of Houston

Accelerators
Mark Mandelkern
For producing beams of energetic
particles
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Protons, antiprotons and light ions
heavy ions
electrons and positrons
(secondary) neutral beams (photons,
neutrons, neutrinos)
Some accelerator applications
• particle and nuclear physics
• synchrotron radiation
– materials science, biology
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medical radiation therapy
isotope production
plasma heating
high energy X-ray production
– non-destructive testing, food sterilization
Accelerators in particle physics
• probe small-scale structure
• l = h/p=197 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
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
– Waveguide:electrons only(SLAC, NLC)
Pelletron
Van de Graff
Cockcroft-Walton principle
ISIS Cockcroft-Walton
Wideroe Linac
Alvarez Linac
Radiofrequency Quadrupole RFQ
SLAC Linac
SLAC Waveguide
Phase Stability
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)
Cyclotron animation
First cyclotron
TRIUMF
Strong focusing principle
Strong focusing animation
HEP Accelerator Systems
• FNAL Tevatron(1 TeV p)
– CW(750 keV):Linac:Booster(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):SPS:LEP
FNAL Tevatron Tunnel
Synchrotron radiation
W=(e2/3e0)(g4b3/R)
loss per turn
Ec=(hc/2p)(3g3/2R)
peak energy
g=E/mc2
LEP: 100 GeV/beam: R=4.9km W~3 GeV Ec~ 90
keV(hard X-ray) 288 SC RF cavities
Tevatron: E=1 TeV R=1.1km W~ 10 eV Ec~0.4 eV
LHC: E=7 TeV R=4.9 kmW~5 keV, Ec~27 eV
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-?)
Why Colliders?
• Fixed target (pp)
– Ecm2=mb2+mt2+2Ebmt
– Eb=1 TeV mb=mt=0.938 GeV Ecm=43.3 GeV
• Symmetrical Collider
– Ecm=Eb+Et
– Eb=Et= 1 TeV Ecm=2 TeV
How Colliders?
Event Rate = Ls
L=f 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
LEP
LHC
SLC/NLC