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Accelerators

Ken PeachJohn Adams Institute for Accelerator Science

Charters School

28th February 2007

Ken Peach John Adams Institute 28 2 2007 2

Outline

• Accelerators– Early Accelerators– Accelerators today

• Science– Particle Physics and Cosmology– Other sciences

• Society– Medicine

• Summary & Conclusions

http://www.adams-institute.ac.uk Ken.Peach@adams-institute.ac.uk

Accelerators

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The 1st Accelerator Experiment?• Galileo Galilei (1564 - 1642)

• (Probably apocryphal)

– Use Leaning Tower of PisaLeaning Tower of Pisa • time to fall independent weight

– Result?

• The Law of Gravity!

1 22

12N

mGF

r

m

Galileo Aristotle

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Lessons

1. Cost is significant

2. Limit to energy with the same technology

3. Higher energy needs a different approach

not more of the “old” method

Étienne & Joseph Montgolfier

Galileo Aristotle

1 22

12N

mGF

r

m

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Cockcroft and Walton (UK)

Early accelerator

From the early days to

ISIS@RAL

The “Leaning” Cockcroft &

Walton

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+ +-

The Linear Accelerator (Linac)

+ -+

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The Linear Accelerator (Linac)

-+ -+ -+ -+- + - + - + - +Each voltage step is “modest”

Inside a Linac

The LEP Linear Injector Linac

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SLAC – The Stanford Linear Accelerator (Centre)

50 GeV electrons and positrons

2.8GHz RF

17MeV/m

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Lawrence (US) – the Cyclotron

The Chicago Cyclotron Magnet

Lawrence’s 1st cyclotron

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The Cyclotron

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Lawrence (US) – the Cyclotron

The Chicago Cyclotron Magnet

Lawrence’s 1st cyclotron

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Mark Oliphant and the Birmingham Synchrotron

1940s, Mark Oliphant

• designed and built a 1 GeV proton synchrotron at Birmingham

• (almost) the first working proton synchrotron in the world!

(Just beaten by Berkeley)

Mark Oliphant

1901-2000

Oliphant also build a 400MeV cyclotron in Birmingham in the late 1930s

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CERN in Geneva (& France)

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LEP – the Large Electron-Positron Collider

The Largest (electron) Synchrotron [so far!]

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Science

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The equation of the Universe!

(after Feynman)

We know the equation of the Universe

U = 1U = 0 The trouble is, we have no idea what U is!!!!

but … we know a lot about what U contains

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How to discover the structure of the Universe

• 3 basic waysLook at it Heat it Smash it

Wavelength Temperature T Energy E

hc/ = kT E=

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Remarkable comment

All three the same fundamental physics!

Uses ‘light’ Uses ‘heat’ T Uses ‘probe’ E

hc/ = kT E=

Photons Photons ‘Photons’

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The Big Bang

BIGBANG

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LEP – the Large Electron-Positron Collider

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ALEPHA detector for LEP Physics

©

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Some events ‘evaporating from the vacuum’

Ze+e- Z+-

Z+ -Zqq

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Some more (complicated) events

Z+- Zqqg

Z4 ‘jets’

ZW+W-

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High Precision Frontier

Known phenomena studiedwith high precision may show

inconsistencies with theory

High Energy Frontier

New phenomena(new particles)

created when the “usable” energy > mc2 [×2]

Accelerators for particle physics

What is needed, and why

2 routes to new knowledge about the fundamental structure of the matter

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HiggsHiggsBosonBosonHiggsHiggsBoson?Boson?

For

ceF

o rce

Car

riers

Car

r iers

ZZ boson

WW boson

photon

ggluon

Generations of Generations of matter matter

-neutrino

tau

bbottom

ttop

III III

-neutrino

muon

sstrange

ccharm

II II

ee-neutrino

eelectron

ddown

upu

I I

Lept

ons

Lept

ons

Qua

rks

Qua

rks

The experimentalist’s view

Each with its own

‘antiparticle’

© Brian Foster

Particles and

Forces

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What remains to be done?

• The Standard Model is a very good description of the Universe at the particle scale (~2MW)– But does not explain many things

• Why so many particles?• Why so many forces?• What is mass?

– Why do particles have the masses they have?

• How do neutrinos get mass?– Are neutrinos different? How do they fit in?

• What is Dark Matter? Dark Energy?• Why is matter different from antimatter?

– (Where did all the antimatter go?)

• Where does gravity fit in?

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The Large Hadron Collider @ CERN

• 7,000,000,000,000 volt protons colliding head on

• 40,000,000 times per second

protons protons

What Happens?

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The Large Hadron Collider @ CERN

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LHC machine status

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The Large Hadron Collider

ATLAS

CMS

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Status 16th February 2006

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Status 23rd February 2007

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What does the LHC hope to find?

1. The Higgs Boson– Complete the “Standard Model”– Confirm that we “understand” mass

• But perhaps not !

2. Find something new– Clues to “Beyond the Standard Model”

• Towards a “Standard Theory”• That Explains as well as Describes

– Supersymmetry• A new completely type of particle

Could explain Dark Matter

– Extra Dimensions• We lives in 1 time + 3 out of n space dimensions!

– The unexpected

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The Unexpected

protons protons

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After the LHC?

– What next?– Need to study the new discoveries

– Precision measurements

– History shows that– Proton colliders are good at discovery– e+e- colliders are good at precision

measurement

– Need higher energy than LEP– But synchrotrons at the limit

– Synchrotron radiation– E4 at fixed radius

– i.e. 2 Energy = 16 Power or 16 Radius!

– Back to the Linac!!!!

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Why an e+e- collider?

After Barry Barish

LEP

LHC

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A Linear Collider

~30 km!

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The heart of the Linear Collider

http://www.adams-institute.ac.uk Ken.Peach@adams-institute.ac.uk

Other Sciences

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Accelerators for other sciences

Neutron sources

X-ray sources

Nuclear Physics

Accelerators for other applications

Accelerators in Medicine

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NIMROD @ RAL & NINA @ Daresbury

• Built in the 1960s– NIMROD @ RAL

• 8 GeV proton synchrotron

– NINA @ Daresbury• 3 GeV electron synchrotron

• Both closed in the 1970s!– The UK’s accelerators were “@CERN”

• New projects from their ashes– ISIS @ RAL

• 800MeV proton synchrotron for a

Spallation Neutron Source

– SRS @ Daresbury• 2GeV Synchrotron Radiation Source

}

Particle Accelerators for other sciences

(Physics, Chemistry,

Engineering, Biology, Medicine)

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What is a Spallation Neutron Source?

High Energy (~1GeV)High Power (~MW)

(ISIS – 0.16MW)

nn

n

n

n

n n

nTargetProtons

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ISIS @ RALISIS @ RAL

ISIS:50 Hz800 MeV300 µA

ISIS @ RAL

600 Experiments/year1200 Users/year235 UK Groups

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Neutron Scattering (ISIS)

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What is Synchrotron Radiation?

Motion of a charged particle (an electron) in a magnetic field

When ultra-relativistic, emits x-rays tangential to the motion

X-ray

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SRS @ Daresbury

Sir John Walker,

Nobel Prize in Chemistry, 1997

“for elucidation of the

enzymatic mechanism underlying

the synthesis of adenosine triphosphate

(ATP)”

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Examples of use of Synchrotron Radiation

CCLRC/SRD annual report

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Diamond & the ISIS 2nd Target Station

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SocietyAccelerators in Medicine

Proton and Heavy Ion Therapy

(not discussed: Accelerator Driven Reactors

Accelerator Driven Transmutation of radioactive Waste)

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Incidence of Cancer in the UK

• 13.5% probability, all types (except skin cancer)– Around half are associated with specific risks– Statistically, some will be close to sensitive tissue

• And difficult to treat surgically or chemically

Source: Cancer Research UK

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The Clatterbridge Centre for Oncology

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The Clatterbridge Centre for Oncology

• Established 1989 – First hospital based

proton therapy – >1400 patients with

ocular melanoma– First example of 3D

computer treatment planning in UK;

• eye gaze direction used to obtain best approach angle to eye.

• Unsung success story of British Oncology!

After Bleddyn Jones

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The ‘spread-out’ Bragg Peak –plateau effect

[SOBP]

65MeV 140meV200MeV

5 10 cmDepth

Dose (%)

Effective Range varies with proton Energy

Why use protons?

After Bleddyn Jones

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Single field100

50

2 opposed fields200

50

3 co-planar fields300

50

PROTONS X-Rays

2 opposed fields

3 co-planar fields

Single field

100

200

100

Depth Depth

% DOSE

%DOSE

How does it work?

After Bleddyn Jones

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X-Rays

Protons 30050 50

60

100

80 80150

0

60

Axial view

3 Field techniques

After Bleddyn Jones

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Many centres world-wide

based on information of the Particle Therapy Co-Operative Group (PTCOG)

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Hadron Therapy in Chiba(Japan)

Stolen from Loma LindaBorrowed from Rob Edgecock

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Medical applications of accelerators

• Oncology– Protons, heavy ions, electrons

• Why so little interest in the UK?

• Preparation of radio-nuclides

• Requires precision control of– Energy– Dose

• Just like the linear collider (energy, luminosity)

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Summary and Conclusions

• Particle Accelerators are important tools– For Particle Physics (& cosmology)

• Science [and Society] will benefit– Science

• understanding the structure of (bio)materials

– Society• New and better materials• New and better drugs• New (and better?) therapies

• and they are fun too!