Acceleration of Charged Particles by Dr.Ken Taylor
Why Accelerate Particles? To probe sub-nuclear world
Tw o-fold Nature ofparticle Accelerators 1. To provide high energy projectiles for: Breaking particles into constituents Creating new particles according to mass - energy relation E = mc 2 Pair Production Pair Annihilation
Two-Fold N atu re of Particle A ccelerators Pair Production Rochester, C. D. and J. G. Wilson; Cloud Chamber Photographs of the Cosmic Radiation; Pergamon Press, Ltd., 1952.
Tw o-fold Nature Accelerators ofparticle 2. To serve as a microscope in which projectiles of ultra-short wavelength probe the sub-nuclear world according to the matter - wave relation λ = h/p.
NaturalParticle Accelerators 1.Radioactive Sources Beta Particle Em ission Mn - 56 Fe - 56 + β + γ Alpha Particle Em ission Ra - 226 Rn - 222 + He - 4 (α)
N atu ral Particle A ccelerators Beta Decay Gouiran, Robert; Particles and Accelerators; World University Press; 1967 page178.
N atu ral Particle A ccelerators Beta Spectrum Spectrum suggested neutrinos Sproull, Robert L., and W. Andrew Phillips; Modern Physics The Quantum Physics of Atoms, Solids, and Nuclei, Third Edition; John Wiley and Sons, 1980; page549.
N atu ral Particle A ccelerators Radioactive Decay Modes Fernow, Richard; Introduction to Experimental Particle Physics; Cambridge University Press; 1986; page 119.
NaturalParticle Accelerators 2.Cosm ic Radiation Prim ary --- Protons Secondary --- Muons Electrons Neutrons
Cosm ic Rays Fernow, Richard; Introduction to Experimental Particle Physics; Cambridge University Press; 1986; page 118.
NaturalParticle Accelerators 3.Disadvantages ofnatural Particle Accelerators LAC K OF CONTROL OVER PARTICLE: Type Energy Direction Flux A rrivaltim e
Electrostatic Accelerators C rookes s Tube ---1st R esearch Accelerator Used by J.J.Thom son in Measuring e/m ofelectron
Electrostatic A ccelerator Crookes s Tube Gouiran, Robert; Particles and Accelerators; World University Press; 1967; page 19.
Electrostatic Accelerators TV A ccelerator Open structure TV set at Microcosm Museum - CERN; Photo by Ken Taylor
Electrostatic Accelerators: Cockcroft - Walton Invented at Fam ous C avendish Laboratory in 1932 Used to produce th e 1 st nuclear disintegration produced by m an-made accelerator p + Li 7 α + α + 17 M ev
Electrostatic Accelerators: Cockcroft - Walton C ascading Voltage Doubler Analogous to charging capacitors in parallel and discharging in series (high im pedance,low current voltage source)
Cockroft- Walton Voltage doubler circuit - unit cell Cockroft- Walton Voltage quadrupler circuit
Retired Cockcroft-Walton Accelerator - Microcosm Museum -CERN Photo by Ken Taylor
Retired Cockcroft-Walton Accelerator - Microcosm Museum -CERN Photo by Ken Taylor
Electrostatic Accelerators: Disadvantages Electrostatic Accelerators lim ited to 1 M V (Due to arcing discharges) Allcharges accelerated th rou gh gaps having electric fields established by potentialdifferences
Radio-Frequency Accelerator: The LINAC First con stru cted by R.Wideroe in 1928 --- 50 kev Idea:replace single wide gap oflarge potentialdifference with succession of many sm aller gaps having sm aller potentialdifferences Thus:acceleration tak es place across a sequence ofa large num ber ofsm all steps (rather than one large step)
RF A ccelerating Cavities Wilson, Robert R; Scientific American, The Next Generation of Particle Accelerators; January, 1980; Volume 242, Number 1
RF A ccelerating Wavefront Fernow, Richard; Introduction to Experimental Particle Physics; Cambridge University Press; 1986; page 96.
Klystron RF G en erator Fermilab LINAC Photo by Ken Taylor
Klystron RF G en erator Fermilab LINAC Photo by Ken Taylor
Circular Accelerators:The Synchrotron Idea:R euse sam e accelerating structure (RF typ e --- similar to LINAC)to save space and m oney Circular array ofbending magnets (causes particles to circulate again and again and obtain energy boosts during each orbit) Magnetic field ofm agnets increases as particle energy increases in order to maintain constant radius ofm otion
M acro-view of Synchrotron Gouiran, Robert; Particles and Accelerators; World University Press; 1967; page 208
Synchrotron M agnetic force provides requ ired centripetalacceleration of moving charges Required force to maintain fixed radius increases due to increase in velocity and m ass ofcharges
Synchrotron M aximum magnetic field of bending m agnets approxim ately 8-10 Tesla M aximum field places lim it on energy ofaccelerator for given radius or accelerator size Greater energies th u s requ ire greater realestate to reduce requ ired centripetalforce (due to larger radius)
Driver Motor Fermilab Helium Liquifier Plant Photo by Ken Taylor
Heliu m Com pressing Facilities Fermilab Photo by Ken Taylor
Liquid Heliu m Storage Tank Fermilab Photo by Ken Taylor
M icro-view of Synchrotron Wilson, Robert R; Scientific American, The Next Generation of Particle Accelerators; January, 1980; Volume 242, Number 1
Synchrotron Radiation E α E 4 /RM 4 Electrons in circular accelerators Protons in circular accelerators (allth ings being equal,protons suffer 10 13 times less radiative losses th an electrons)
Fixed-Target Beam s vs Colliders Collider beam s enjoy much greater collision energies th an th ose for fixed-target experiments For colliders --- The collision energy is tw ice th e energy ofeith er beam
Collid er D etector at Ferm ilab Photo by Ken Taylor
CD F Fermilab Photo by Ken Taylor
CDF Fermilab Photo by Ken Taylor
CDF and Assem bly Area Fermilab Photo by Ken Taylor
Aleph Experim ent Hall CERN Photo by Ken Taylor
TunnelNear Aleph Experim ent Hall CERN - Geneva, Switzerland Photo by Ken Taylor
Atlas C on stru ction Site CERN Photo by Ken Taylor
Atlas C on stru ction Workers CERN Photo by Ken Taylor
A tlas TunnelE xcavation (looking dow n) CERN Photo by Ken Taylor
Atlas Utility Tunnel(looking dow n) CERN Photo by Ken Taylor
Dr.Ken Taylor 2001 QuarkNet Associate Teacher Institu te Southern Methodist University