Introduction to Accelerators, African School of Physics, KNUST, Kumasi, Ghana; L. Rivkin, PSI & EPFL...

Introduction to Accelerators, African School of Physics, KNUST, Kumasi, Ghana; L. Rivkin, PSI & EPFL

Particle Accelerators: An introduction

Lenny RivkinSwiss Institute of Technology Lausanne (EPFL)

Paul Scherrer Institute (PSI)Switzerland


CERN

PSI

EPFL


The Role of Accelerators in Physical and Life Sciences

“It is an historical fact that scientific revolutions are more often driven by new tools than by new concepts”

Freeman Dyson


Particle beams: main uses(protons, electrons, photons, neutrons, muons, neutrinos etc.)

Research in basic subatomic physics

Analysis of physical, chemical and biological samples

Modification of physical, chemical and biological properties of matter


Medicine35%

Industry60%

Research5%

Accelerators in the world

New technologies

New ApplicationsTotal number ~ 30’000growing at about 10% per year

Introduction to Accelerators, African School of Physics, KNUST, Kumasi, Ghana; L. Rivkin, PSI & EPFLH. Dosch, DESY

Introduction to Accelerators, African School of Physics, KNUST, Kumasi, Ghana; L. Rivkin, PSI & EPFLR. W. Hamm, 9th ICFA Seminar, October’08, SLAC


• High energy frontier

• High luminosity frontier

• High precision measurements

ACCELERATORS: INSTRUMENTS FOR PARTICLE PHYSICS


Energy available in collisions (center-of-mass energy)

Fixed target geometry

Colliding beams

or for unequal energies

E

E E

EEcm 2

EmcEcm 22

212 EEEcm

Livingston plot

Equivalent energy of a fixed target accelerator

2

2

2mc

EE cm


BECAME THE MOST POWERFUL

ACCELERATOR FOR RESEARCH IN PARTICLE PHYSICS

IP

IP

COLLISION AT THE

IP (Interaction Point)

COLLIDERCIRCULAR

Luminosity

scmANf 2

2 1L

Interaction rate

int Ldtdn

R

Point cross-section

2int

1s

Unit: barn = 10 -24 cm2

1 fb

1 pb

History of luminosity in the world

1034cm-2s-

1=10 /nb/s


Scaling of high energy proton rings

cGeVpmTB...29979.0

1

LEP tunnel: 1 TeV per 1 Tesla

Ecosts,


Scaling of high energy electron rings

Electrons emit synchrotron radiation

2Ecosts,

2

4

PowerE2

4

cost

Eba

Ecosts :CollidersLinear


Linear Colliders

30 – 40 kmRF in RF out

E

e+ e-

damping ring

main linac

beam delivery

rf power source

particles “surf” the electromagnetic wave

Introduction to Accelerators, African School of Physics, KNUST, Kumasi, Ghana; L. Rivkin, PSI & EPFL24

Tunnel implementations (laser straight)

Central MDI & Interaction Region


1 professional lifespan!

Beyound LHC? An 80 km tunnel?

John Osborne (CERN), Caroline Waaijer (CERN)

Magnetic field Energy c.o.m.

8.3 Tesla 42 TeV

16 Tesla 80 TeV

20 Tesla 100 TeV

Enrico Fermi’s (1954) Space-Based World Machine

Cosmic accelerators

Constellation Pictor: Pictor A X-ray imageX-ray jet originating near a giant black hole

800‘000 light years

Chandra X-Ray Observatory


Useful books and references

H. Wiedemann, Particle Accelerator Physics I and IISpringer Study Edition, 2003

K. Wille, The physics of Particle Accelerators: An IntroductionOxford University Press, 2001

D. A. Edwards, M. J. Syphers, An Introduction to the Physics of High Energy AcceleratorsJohn Wiley & Sons, Inc. 1993

E.J.N. Wilson, An Introduction to Particle AcceleratorsOxford University Press, 2001

A. W. Chao, M. Tigner, Handbook of Accelerator Physics and Engineering, World Scientific 1999

CERN Accelerator School (CAS) proceedingsE. D. Courant and H. S. Snyder, Annals of Physics: 3, 1 - 48 (1958)M. Sands, SLAC-121


1980 James W. Cronin and Val L. Fitch

Cronin and Fitch concluded in 1964 that CP (charge-parity) symmetry is violated in the decay of neutral K mesons based upon their experiments using the Brookhaven Alternating Gradient Synchrotron [28].

1981 Kai M. Siegbahn Siegbahn invented a weak-focusing principle for betatrons in 1944 with which he made significant improvements in high-resolution electron spectroscopy [29].

1983 William A. Fowler Fowler collaborated on and analyzed accelerator-based experiments in 1958 [30], which he used to support his hypothesis on stellar-fusion processes in 1957 [31].

1984 Carlo Rubbia and Simon van der Meer

Rubbia led a team of physicists who observed the intermediate vector bosons W and Z in 1983 using CERN’s proton-antiproton collider [32], and van der Meer developed much of the instrumentation needed for these experiments [33].

1986 Ernst Ruska Ruska built the first electron microscope in 1933 based upon a magnetic optical system that provided large magnification [34].

1988 Leon M. Lederman, Melvin Schwartz, and Jack Steinberger

Lederman, Schwartz, and Steinberger discovered the muon neutrino in 1962 using Brookhaven’s Alternating Gradient Synchrotron [35].

1989 Wolfgang Paul Paul’s idea in the early 1950s of building ion traps grew out of accelerator physics [36].

1990 Jerome I. Friedman, Henry W. Kendall, and Richard E. Taylor

Friedman, Kendall, and Taylor’s experiments in 1974 on deep inelastic scattering of electrons on protons and bound neutrons used the SLAC linac [37].

1992 Georges Charpak Charpak’s development of multiwire proportional chambers in 1970 were made possible by accelerator-based testing at CERN [38].

1995 Martin L. Perl Perl discovered the tau lepton in 1975 using Stanford’s SPEAR collider [39].

2004 David J. Gross, Frank Wilczek, and H. David Politzer

Gross, Wilczek, and Politzer discovered asymptotic freedom in the theory of strong interactions in 1973 based upon results from the SLAC linac on electron-proton scattering [40].

2008 Makoto Kobayashi and Toshihide Maskawa

Kobayashi and Maskawa’s theory of quark mixing in 1973 was confirmed by results from the KEKB accelerator at KEK (High Energy Accelerator Research Organization) in Tsukuba, Ibaraki Prefecture, Japan, and the PEP II (Positron Electron Project II) at SLAC [41], which showed that quark mixing in the six-quark model is the dominant source of broken symmetry [42].

Year Name Accelerator-Science Contribution to Nobel Prize-Winning Research

1939 Ernest O. Lawrence Lawrence invented the cyclotron at the University of Californian at Berkeley in 1929 [12].

1951 John D. Cockcroft and Ernest T.S. Walton

Cockcroft and Walton invented their eponymous linear positive-ion accelerator at the Cavendish Laboratory in Cambridge, England, in 1932 [13].

1952 Felix Bloch Bloch used a cyclotron at the Crocker Radiation Laboratory at the University of California at Berkeley in his discovery of the magnetic moment of the neutron in 1940 [14].

1957 Tsung-Dao Lee and Chen Ning Yang

Lee and Yang analyzed data on K mesons (θ and τ) from Bevatron experiments at the Lawrence Radiation Laboratory in 1955 [15], which supported their idea in 1956 that parity is not conserved in weak interactions [16].

1959 Emilio G. Segrè and Owen Chamberlain

Segrè and Chamberlain discovered the antiproton in 1955 using the Bevatron at the Lawrence Radiation Laboratory [17].

1960 Donald A. Glaser Glaser tested his first experimental six-inch bubble chamber in 1955 with high-energy protons produced by the Brookhaven Cosmotron [18].

1961 Robert Hofstadter Hofstadter carried out electron-scattering experiments on carbon-12 and oxygen-16 in 1959 using the SLAC linac and thereby made discoveries on the structure of nucleons [19].

1963 Maria Goeppert Mayer Goeppert Mayer analyzed experiments using neutron beams produced by the University of Chicago cyclotron in 1947 to measure the nuclear binding energies of krypton and xenon [20], which led to her discoveries on high magic numbers in 1948 [21].

1967 Hans A. Bethe Bethe analyzed nuclear reactions involving accelerated protons and other nuclei whereby he discovered in 1939 how energy is produced in stars [22].

1968 Luis W. Alvarez Alvarez discovered a large number of resonance states using his fifteen-inch hydrogen bubble chamber and high-energy proton beams from the Bevatron at the Lawrence Radiation Laboratory [23].

1976 Burton Richter and Samuel C.C. Ting

Richter discovered the J/ particle in 1974 using the SPEAR collider at Stanford [24], and Ting discovered the J/ particle independently in 1974 using the Brookhaven Alternating Gradient Synchrotron [25].

1979 Sheldon L. Glashow, Abdus Salam, and Steven Weinberg

Glashow, Salam, and Weinberg cited experiments on the bombardment of nuclei with neutrinos at CERN in 1973 [26] as confirmation of their prediction of weak neutral currents [27].

24 Nobel Prizes in Physics that had direct contribution from accelerators


19 Nobels with X-rays

Chemistry1936: Peter Debye1962: Max Purutz and Sir John

Kendrew1976 William Lipscomb1985 Herbert Hauptman and

Jerome Karle1988 Johann Deisenhofer, Robert

Huber and Hartmut Michel1997 Paul D. Boyer and John E.

Walker2003 Peter Agre and Roderick

Mackinnon2009 V. Ramakrishnan, Th. A.

Steitz, A. E. Yonath

Physics1901 Wilhem Rontgen1914 Max von Laue1915 Sir William Bragg and son1917 Charles Barkla1924 Karl Siegbahn1927 Arthur Compton1981 Kai Siegbahn

Medicine1946 Hermann Muller1962 Frances Crick, James

Watson and Maurice Wilkins1979 Alan Cormack and Godfrey

Hounsfield


Light sources


60‘000 users world-wide


The “brightness” of a light source:

Flux, F

FS x W

Brightness = constant x _________

Angular divergence, W

Source area, S

Steep rise in brightness

1021

1015

109

1900 1950 2000

Wigglers

Bending magnets

Undulators

Rotating anode

SPring8

ESRF

APS

Bertha Roentgen’s hand(exposure: 20 min)

Moore’s Law for semiconductors

SLSSOLEIL (F)DIAMOND (UK) …

the second wave

XFEL


The electron beam “emittance”:

Emittance = S x W

Angular divergence, W

Source area, S The brightness

depends on the geometry of the source, i.e., on the electron beam emittance


Medical applications

Protons – treatment of tumors

improved radiation therapy> 800 patients treated with deep-seated tumors> 5800 patients treated with eye tumors

> 50 % of patients are below 40 years old

25%

12%

15%14%

13%

14%

7%

<20

21-30

31-40

41-50

51-60

61-70

>70


BRAGG PEAK

PROTON BEAM

… ALLOWS THE TREATMENT OF DEEP INSIDE LYING TUMORS WITH BEST

PROTECTION OF THE SURROUNDING


Comparison of Characteristics of Photons und Protons for Radiation Therapy

Tumor

Depth (cm)

Dose

SPOT SCANNING

ENERGY

PO

SIT

ION


GANTRY


Aim of proton therapy: Dose concentrated in the tumor volume,low dose or no dose to healthy tissues

Protons IMRT -Photons


First accelerators


Electrostatic linear accelerator

SLS DC electron gun: U = 90 kV, Ek = 90 keV

U- +

CATHODE

2

vm 1)(γcm EeU

2o2

ok non-relativistic approxim.

COCKROFT WALTON

VAN DE GRAFF

TANDEM

PELLETRON


First accelerators:Cockcroft and Walton 1932

MeV2.177 pLi


Going beyond 1 MV

Can we repeat the process of DC acceleration?

Need time varying fields

tV

tV

t


Wideroe Linac 1928Wideroe Linac 1928

Drift tubesIon source Acceleration of slow ions

RF TransmitterfRF ~ 1–7 MHz

Beam

04.0


FOR THE SAME ENERGY EXTRACTED FROM THE FIELD,

A PARTICLE WITH LOWER MASS IS MORE RELATIVISTIC

v/c

eU [MeV]0

0.2

0.4

0.6

0.8

1

0.001 0.01 0.1 1 10 100 1000 10000

c

v

2

11

v

c

e p

oE

eU1

U- +

CATHODE


FERMILAB

ALAVAREZ DTL

The drift tubes are enclosed in a single resonant tank in order to avoid large radiative energy losses at higher frequencies (e.g. 200 MHz)

ALVAREZ LINACS WORK UP TO b ~ 0.4

A NEW STRUCTURE IS REQUIRED FOR RELATIVISTIC PARTICLES !


Electron RF linacs

Disk loaded accelerating structure slows down the RF wave to let electron keep up with it


SLS 100 MeV RF linac


Lawrence: coiled up linac


First accelerators: cyclotron

Livingston and Lawrence4.5 inch model cyclotron27 inch cyclotron


First accelerators: cyclotron


Rolf Wideröe‘s notebook


Donald Kerst: first betatron (1940)

"Ausserordentlichhochgeschwindigkeitelektronenentwickelndenschwerarbeitsbeigollitron"

Introduction to Accelerators, African School of Physics, KNUST, Kumasi, Ghana; L. Rivkin, PSI & EPFL...

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