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A Brief History of Accelerators�

Adopted by P. Snopok from J. Kunz (2019) and L. Spentzouris (2018)

USPAS Summer 2022

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What Is a Particle Accelerator?

Structure to accelerate particles

Usually protons, electrons

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What Is a Particle Accelerator?

Structure to accelerate particles

Usually protons, electrons

Late 1800s, J. J. Thompson’s cathode ray tube

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What Is a Particle Accelerator?

Structure to accelerate particles

Usually protons, electrons

Late 1800s, J. J. Thompson’s cathode ray tube
Nowadays concentrate on the production of “beam”

What do you think is an important characteristic?

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What Is a Particle Accelerator?

Structure to accelerate particles

Usually protons, electrons

Late 1800s, J. J. Thompson’s cathode ray tube
Nowadays concentrate on the production of “beam”

Spatial divergence
Momentum spread
Desired location/time
Energy spread
Polarization
Etc.

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High Energy (high field)

Compact machines

🡺

Dense beams

Number of particles /

Size of beam

Timing

🡺

Short pulse

Rapid or continuous cycle

🡺

What is needed?

How is it done?

Source

Accelerating structures

Magnets

Diagnostics

Efficiency

🡺

Wall plug to beam power

Longitudinal oscillations

Transverse oscillations

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Why Do We Need Particle Accelerators?

Subatomic particle physics

Standard Model, Higgs, neutrinos

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Why Do We Need Particle Accelerators?

Subatomic particle physics

Standard Model, Higgs, neutrinos

Nuclear research

Nuclear energy levels, �quark-gluon plasma studies

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Why Do We Need Particle Accelerators?

Subatomic particle physics

Standard Model, Higgs, neutrinos

Nuclear research

Nuclear energy levels, quark-gluon plasma studies

Synchrotron radiation source (light source)

High precision imaging, study of atomic structure, chemistry, condensed matter physics, biology, and technology

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http://www.anl.gov/articles/how-hiv-infects-cells

For example:

Scientists, with high-brightness x-rays (Argonne APS) determined the structure of a cell-surface receptor that most strains of HIV use to gain entry to human immune cells.

They also showed where an HIV drug, attaches to cells and blocks HIV’s entry

Light Sources – generate high frequency light

Human Genome project: identified

20,000-25,000 genes in human DNA

that regulate human body function.

Study proteins

Develop pharmaceuticals

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Why Do We Need Particle Accelerators?

Subatomic particle physics

Standard Model, Higgs, neutrinos

Nuclear research

Nuclear energy levels, quark-gluon plasma studies

Synchrotron radiation source (light source)

High precision imaging study of atomic structure, chemistry, condensed matter physics, biology, and technology

Medical applications
Ion beams for plasma heating in fusion reactor experiments
Oil and natural gas exploration
Food sterilization

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Acceleration Schemes

High voltage is key! Cathode ray tube 10 kV

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Acceleration Schemes

High voltage is key! Cathode ray tube 10 kV
Cockcroft and Walton: 750 kV

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Acceleration Schemes

Periodic passage through voltage system

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Cyclotron

Ernest Lawrence

1929-30

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Courtesy Fermilab visual services

Alternating Electromagnetic ‘RF’ accelerating fields

Pillbox Cavity

With drift tubes for shielding decelerating fields

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Courtesy FNAL computational accelerator

Physics group using Synergia, under SciDAC

Simulated 3D space of Fermilab Booster

Time

Longitudinal Oscillations

Bunches

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(FNAL) Conventional copper standing-wave accelerating structures

(SLAC) Conventional copper

traveling-wave accelerating structures

(Jefferson lab) Superconducting

niobium accelerating structure

Courtesy Fermilab Visual Services

Courtesy Jefferson Lab

Courtesy Stanford Linear Accelerator Center

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Linear Accelerator Example

Typically electron/positron

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Linear Accelerator Example

Typically electron/positron

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Synchrotron

Typically anti/proton

RF cavities (covered in detail tomorrow)
Strong focusing (discussed later today)

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Courtesy Fermilab Visual Services

Booster

Main Injector & Recycler

Tevatron

Pbar Accumulator and Debuncher

Pointing the beam:

MI

Recycler

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Electromagnets

Courtesy Fermilab Visual Services

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How much bending field do you need

(say for 500 m circumference, and 8.9 Gev)?

What if you want to leave some gaps for devices other than bending magnets?

What if you want to increase the beam energy?

See Transverse dynamics notes page 1-5

ρ = 79.58 m

pc = 8.8886 x 10³MeV

B = 0.37 T

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x

Magnetic quadrupole fields provide restoring force for transverse errors

Focusing the beam

Courtesy Fermilab Visual Services

Courtesy K. Steffen ‘Basic course on accelerator optics’

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What is the magnetic field gradient B’ of a quadrupole magnet?

Material	Permeability
Vacuum	4π x 10^-7
FNAL MI dipole steel	2.3 x 10^-4
Iron	6.3 x 10^-3

See Magnet elements notes

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B.J. Holzer

Single particle trajectories within beam envelope

Harmonic restoring forces correct small trajectory errors

in all three possible directions of motion

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Courtesy Fermilab Visual Services

Quadrupole, Dipole, Sextupole

Superconducting coils

Superconducting quadrupole

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Beam intensity

Dipole magnet current

time (s)

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FNAL machine	Cycle time	Final Energy
Pre-accelerator	20	750 keV	.04
Linac	Pulse: 200 Beam: 20	400 MeV	.71
Booster	66 ms	8 GeV	.9945
Main Injector	Pbar prod. 2-3 s Tev inj. 5 s	120 GeV 150 GeV	.99997 .99998
Tevatron	60-200 s	980 TeV	.9999995

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A proton has a kinetic energy of 3 GeV.

What are beta and gamma of the proton?

β

electrons

protons

20

5000

Total Energy [MeV]

See relativity notes

γ = 4.2

β = 0.97

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[Mandatory] log-linear Livingston plot

Original plot