applications of accelerators

Philip Burrows

John Adams Institute for Accelerator Science

Oxford University

Applications of Accelerators

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Lecture 2 outline

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• Application of accelerators for fundamental discoveries

• A bit of history

• Colliders

• Large Hadron Collider

• After the Large Hadron Collider

Scientific importance of accelerators

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• 30% of physics Nobel Prizes

awarded for work based

on accelerators

• Increasing number of non-physics

Nobel Prizes being awarded

for work reliant on accelerators!

Accelerator-related Physics Nobel Prizes

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• 1901 Roentgen: X rays• 1905 Lenard: cathode rays• 1906 JJ Thomson: electron• 1914 von Laue: X-ray diffraction• 1915 WH+WL Bragg: X-ray crystallography• 1925 Franck, Hertz: laws of impact of e on atoms• 1927 Compton: X-ray scattering• 1937 Davisson, Germer: diffraction of electrons• 1939 Lawrence: cyclotron

Accelerator-related Physics Nobel Prizes

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• 1943 Stern: magnetic moment of proton• 1951 Cockcroft, Walton: artificial acceleration• 1959 Segre, Chamberlain: antiproton discovery• 1961 Hofstadter: structure of nucleons• 1968 Alvarez: discovery of particle resonances• 1969 Gell-Mann: classification of el. particles• 1976 Richter, Ting: charmed quark• 1979 Glashow, Salam, Weinberg: Standard Model• 1980 Cronin, Fitch: symmetry violation in kaons

Accelerator-related Physics Nobel Prizes

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• 1984 Rubbia, van der Meer: W + Z particles • 1986 Ruska: electron microscope• 1988 Ledermann, Schwartz, Steinerger: mu nu• 1990 Friedmann, Kendall, Taylor: quarks• 1992 Charpak: multi-wire proportional chamber• 1994 Brockhouse, Shull: neutron scattering• 1995 Perl: tau lepton discovery• 2004 Gross, Pollitzer, Wilczek: asymptotic freedom• 2008 Nambu, Kobayashi, Maskawa: broken symm.

Particle Physics Periodic Table

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Particle Physics Periodic Table

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Composition of the universe

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Dark Matter

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Composition of the universe

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Dark Energy

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Recreating conditions of early universe

Older ….. larger … colder ….less energetic

nowBig Bang

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Telescopes to the early universe

Older ….. larger … colder ….less energetic

nowBig Bang

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Large Hadron Collider (LHC)

Best window

we have on

matter in the

universe, at

ultra-early

times and at

ultra-small scales

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Interesting speculations

All eyes on collider as it comes to life

Will atom smasher signal end of the world?

Le LHC, un succès européen à célébrer

Large Hadron Collider e International Linear Collider a caccia del bosone di Higgs

Wir stoßen die Tür zum dunklen Universum auf

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For physics studies seeHeavy ion physics (Barbara Jacak)

Standard Model (Harald Fritzsch)

The LHC and the Standard Model (Albert de Roeck)

Beyond the Standard Model (John Ellis)

CP violation (Yosef Nir)

Detectors (Emmanuel Tsesmelis)

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Accelerators

• Want to see what matter is made of

• Smash matter apart and look for the building blocks

• Take small pieces of matter:

accelerate them to very high energy

crash them into one another

• LHC: protons crashing into protons head-on

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High energy is critical

Size of structure we can probe with a collider like LHC= h / p (de Broglie, 1924)

h = Planck’s constant = 6.63 x 10**-34 Jsp = momentum of protons

The larger the momentum (energy), the smaller the size

LHC exploring structure of matter at 10**20 m scale

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Why build colliders?

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Why build colliders?

60 mph stationary

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Why build colliders?

60 mph stationary

30 mph 30 mph

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Why build colliders?

60 mph stationary

30 mph 30 mph

For speeds

well below

light speed:

same damage!

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Why build colliders?

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Why build colliders?

Now try this with protons moving near light speed

stationary

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Why build colliders?

Now try this with protons moving near light speed

stationary

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Why build colliders?

stationary

For the same physics,

14,000 times the energy

of each proton in the LHC

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Why colliders?

Most of the energy goes into carrying the momentum forward

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Why colliders?

All the energy available for smashing up the protons

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Large Hadron Collider (LHC)

Largest,

highest-energy

particle

accelerator

CERN,

Geneva

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The fastest racetrack on the planet

The protons will

reach

99.9999991%

speed of light,

and go round the

27km ring 11,000

times per second

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The coldest places in the galaxy

The LHC operates at -271 C (1.9K),

colder than outer space.

A total of 36,800 tonnes are cooled to this temperature.

The largest refrigerator ever

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The emptiest vacuum in the solar system

Ten times more atmosphere on the Moon than inside LHC beam pipes

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The hottest spots in the galaxy

When the two beams of protons collide, they will generate temperatures

1000 million times hotter than the heart of the sun,

but in a minuscule space

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LHC Beams

• Each beam contains 3000 ‘bunches’ of protons

• Each bunch contains 200 billion protons

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Stored Beam Energy

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Stored Beam Energy Equivalents

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Machine Protection System

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LHC Magnets

• 27km tunnel is 50 – 150 m below ground

• Two beams of protons circulating in opposite directions

• Beams controlled by 1800 superconducting magnets, dipoles are of field strength about 8 Tesla

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Stored Magnet Energy

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LHC dipole magnets

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When Magnet Energy Escapes

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Dipole removal from tunnel

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Dipole repair on surface

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Last repaired dipole descending

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Large Hadron Collider (LHC)Back on November 20th 2009

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At last!

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Highest energy subatomic collisions

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Highest energy nuclear collisions

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Luminosity

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N number of particles in each bunchn_b number of bunches per beamf_rep repetition frequency of bunches

Number of particles passing per unit timesigma_x * sigma_ytransverse area of bunches

Number passing per unit time per unit area(‘flux’)

Event rate

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The LHC design luminosity is c. 10**34 / cm**2 / s

Number of events per second

= luminosity * cross section

600 million proton-proton collisions per second

The biggest detectors ever built

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The biggest detectors ever built

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Data rate

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About 10 Petabytes of data per year (at design luminosity)

The most extensive computer system

To analyse the data

tens of thousands of computers

around the world are being harnessed in the Grid

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After LHC?

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?

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LEP:

c. 100 GeV

per beam

Before LHC

Synchrotron radiation

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Power lost due to synchrotron radiation P ~ gamma ** 4 / r**2

gamma = E / mr = radius of trajectory

For LEP each electron loses ~ 3 GeV per turn

P = 10**-6 Watts/electron 18 MW total

Must be compensated by accelerating cavities

Synchrotron radiation

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Suppose we increase LEP beam energy (100 GeV) by factor 5: E 500 GeV, in the same tunnel

P ~ gamma ** 4 / r**2

gamma increases by 5, so P increases by 5**4

this would give P = 5 **4 * 18 MW = 11 GW!

Compensate by increasing radius r?Need 10 x r to reduce P by 100 270km tunnel!

Synchrotron radiation

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What about LHC?

m_proton ~ 2000 * m_electron

for same E, gamma_electron ~ 2000 * gamma_proton

P_electron ~ 2000**4 * P_proton

Even for LHC, E = 70 * LEP, each proton loses only 5 keV per turn

SLAC Linear Collider

c. 50 GeV

per beam

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International Linear Collider

31 km

c. 250 GeV / beam

Philip Burrows IoP Divisional Conference, Glasgow 6//4/1164

Drive Beam Generation Complex

Main Beam Generation Complex

Delahaye

Compact Linear Collider (CLIC)

1.5 TeV / beam

Concept for beam-driven Plasma Wake Field TeV Linear Collider

Drive beam accelerator

DR e- DR e+ main beam e- injector

main beam e+ injector

Beam Delivery and IR

PWFA cells

RF gun

RF separator bunch compressor

Drive beam distribution

PWFA cells

Wim Leemans and Eric Esarey, Physics Today, March 2009

Concept of TeV e+e- collider based on laser-plasma acceleration

Engineering challenges (1)

Civil:

tunnelling, hydrology, stabilisation, survey, metrology, alignment …

Mechanical:

supports, vacuum, materials, surfaces, stability, shielding, personnel protection, remote handling, cooling systems, cryogenics, thermal management …

Electrical:

site power + distribution, powering the beams, magnets, pulsers, power supplies, amplifiers, beam dumps …

Engineering challenges (2)

Controls:

beam position, size, energy, beam orbit steering, feedback to maintain collisions, control system, data acquisition

Systems:

redundancy, reliability, efficiency, machine protection …

Human:

maintenance + repairs, operator interface, remote operation

…

Resume of lecture 2

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• Importance of accelerators for fundamental discoveries

• Why colliders + how they work

• The Large Hadron Collider is amazing

• Future high-energy colliders