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

E.J.N.Wilson - Introduction to Accelerators I – History Slide 6

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

E.J.N.Wilson - Introduction to Accelerators I – History Slide 14

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

E.J.N.Wilson - Introduction to Accelerators I – History Slide 17

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

E.J.N.Wilson - Introduction to Accelerators I – History Slide 21

CERN 25 GeV PS

E.J.N.Wilson - Introduction to Accelerators I – History Slide 22

SPS

E.J.N.Wilson - Introduction to Accelerators I – History Slide 23

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

E.J.N.Wilson - Introduction to Accelerators I – History Slide 25

LEP

LEP(small).pct

E.J.N.Wilson - Introduction to Accelerators I – History Slide 26

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