Accelerators Mark Mandelkern

For producing beams of energetic particles 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 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 = h/p  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=(e 2 /   )(  4    R) loss per turn E c =(hc/2  3    2R) peak energy  E/mc 2 LEP: 100 GeV/beam: R=4.9km W~3 GeV E c ~ 90 keV(hard X-ray) 288 SC RF cavities  evatron: E=1 TeV R=1.1km W~ 10 eV E c ~0.4 eV LHC: E=7 TeV R=4.9 kmW~5 keV, E c ~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) –E cm 2 =m b 2 +m t 2 +2E b m t –E b =1 TeV m b =m t =0.938 GeV E cm =43.3 GeV Symmetrical Collider –E cm =E b +E t –E b =E t = 1 TeV E cm =2 TeV

How Colliders? Event Rate = L  L=f n 1 n 2 /(4  x  y ) n 1 n 2 particles per bunch  x,  y rms horizontal (vertical) beam profile Thus intense bunched beams with tiny beam spots at the interaction points

LEP

LHC

SLC/NLC