E.J.N.Wilson - Introduction to Accelerators I – History Slide 1
Introduction to AcceleratorsLecture I – History – E. Wilson
Electrostatic ideasThe BetatronLinear acceleratorCyclotron and vertical focusingNewton & EinsteinPulsed operation - synchrocyclotronComponents of a synchrotonPhase stabilityThe Woolich betatronGEC electron synchrotronBirmingham synchrotronCosmotronWeak focussing in a synchrotronStrong focussingCERN 25 GeV PSSPS then antiprotonsCenter of mass v. Fixed targetLEPSuperconducting magnets
E.J.N.Wilson - Introduction to Accelerators I – History Slide 2
Electrostatic ideas
Van der Graaf
Cockcroft -Walton
Fallacy
ES/Fallacy.pct
E.J.N.Wilson - Introduction to Accelerators I – History Slide 3
The Betatron
E.J.N.Wilson - Introduction to Accelerators I – History Slide 4
Linear accelerator
� Particle gains energy at each gap� Lengths of drift tubes follow increasing
velocity� Spacing becomes regular as v approaches c� Wideroe’s first linac:
E.J.N.Wilson - Introduction to Accelerators I – History Slide 5
Cyclotron (revolution frequency)
Bρ =mve
=pe
Magnetic rigidity
f rev =v
2πρ=v
2πeBmv
=eB
2πm
Constant revolution frequency
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Lawrence’s Cyclotron
E.J.N.Wilson - Introduction to Accelerators I – History Slide 7
Vertical Focusing
People just got on with the job of building them. Then one day someone was experimenting Figure shows the principle of vertical focusing in a cyclotronIn fact the shims did not do what they had been expected to do Nevertheless the cyclotron began to accelerate much higher currents
E.J.N.Wilson - Introduction to Accelerators I – History Slide 8
Newton & Einstein
Almost all modern accelerators accelerate particles to speeds very close to that of light. In the classical Newton regime the velocity of the particle increases with the square root of the kinetic energy. As v approaches c it is as if the velocity of the particle "saturates" One can pour more and more energy into the particle, giving it ashorter De Broglie wavelength so that it probes deeper into the sub-atomic worldVelocity increases very slowly and asymptotically to that of light
E.J.N.Wilson - Introduction to Accelerators I – History Slide 9
Pulsed operation - synchrocyclotron
E.J.N.Wilson - Introduction to Accelerators I – History Slide 10
Components of a synchroton
E.J.N.Wilson - Introduction to Accelerators I – History Slide 11
Phase stability
V = V0 sin(2πf a + φ s )
PHS.AD5
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Macmillan explains to Lawrence
MAC-LAW.pct
E.J.N.Wilson - Introduction to Accelerators I – History Slide 13
The Woolich Betatron
Fig.2(Woolich).pct
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GEC Electron Synchrotron
E.J.N.Wilson - Introduction to Accelerators I – History Slide 15
Birmingham synchrotron
BHAM-PHONES.pct
E.J.N.Wilson - Introduction to Accelerators I – History Slide 16
Cosmotron
COSMOTRON.PCT
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Weak focussing in a synchrotron
The Cosmotron magnet
Vertical focussing comes from the curvature of the field lines when the field falls off with radius ( positive n-value)Horizontal focussing from the curvature of the pathThe negative field gradient defocuses horizontally and must not be so strong as to cancel the path curvature effect
E.J.N.Wilson - Introduction to Accelerators I – History Slide 18
Cosmotron people
E.Courant -Lattice Designer Stan Livingston - Boss
Snyder -theorist Christofilos - inventor
FOURGUYS.pct
E.J.N.Wilson - Introduction to Accelerators I – History Slide 19
Strong focussing
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CERN at BNL
Odd Dahl, Frank Goward, and Rolf Widerö(right hand trio)
Fig.3(CERNVISITORS).pct
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CERN 25 GeV PS
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SPS
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Center of mass v. Fixed target
W = Energy available in center-of-mass for making new particles For fixed target :
Ec.m. ≅ 2mTEB... and we rapidly run out of money trying to gain a factor 10 in c.m. energy
But a storage ring , colliding two beams, gives:
Ec .m. ≅ 2 EBProblem: Smaller probability that accelerated particles collide .... "Luminosity" of a collider
L = N1N21A
βc2πR
≈ 1029 ...1034cm −2s −1
E.J.N.Wilson - Introduction to Accelerators I – History Slide 24
CERN Antiproton Accumulator
AA.PCT
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LEP
LEP(small).pct
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Superconducting magnets
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Summary of:Lecture I – History – E. Wilson
Electrostatic ideasThe BetatronLinear acceleratorCyclotron and vertical focusingNewton & EinsteinPulsed operation - synchrocyclotronComponents of a synchrotonPhase stabilityThe Woolich betatronGEC electron synchrotronBirmingham synchrotronCosmotronWeak focussing in a synchrotronStrong focussingCERN 25 GeV PSSPS then antiprotonsCenter of mass v. Fixed targetLEPSuperconducting magnets