Applications of Accelerators

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Applications of Accelerators
Philip Burrows John Adams Institute for
Accelerator Science Oxford University
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Lecture 2 outline

• Application of accelerators for fundamental
  discoveries
• A bit of history
• Colliders
• Large Hadron Collider
• After the Large Hadron Collider

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Scientific importance of accelerators

• 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!

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Accelerator-related Physics Nobel Prizes

• 1901 Roentgen X rays
• 1905 Lenard cathode rays
• 1906 JJ Thomson electron
• 1914 von Laue X-ray diffraction
• 1915 WHWL 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

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Accelerator-related Physics Nobel Prizes

• 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

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Accelerator-related Physics Nobel Prizes

• 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.

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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
Big Bang
now
Older .. larger colder .less energetic
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Telescopes to the early universe
Big Bang
now
Older .. larger colder .less energetic
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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 see

• Heavy 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 Plancks constant 6.63 x 10-34 Js
• p momentum of protons
• The larger the momentum (energy), the smaller the
  size
• LHC exploring structure of matter at 1020 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?
For speeds well below light speed same damage!
60 mph
stationary
30 mph
30 mph
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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?
For the same physics, 14,000 times the energy
of each proton in the LHC
stationary
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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

• N number of particles in each bunch
• n_b number of bunches per beam
• f_rep repetition frequency of bunches
• ? Number of particles passing per unit time
• sigma_x sigma_y transverse area of bunches
• Number passing per unit time per unit
  area (flux)

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Event rate
The LHC design luminosity is c. 1034 / cm2 /
s Number of events per second
luminosity cross section ? 600 million
proton-proton collisions per second
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The biggest detectors ever built
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The biggest detectors ever built
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Data rate
About 10 Petabytes of data per year (at design
luminosity)
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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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Before LHC
LEP c. 100 GeV per beam
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Synchrotron radiation
Power lost due to synchrotron radiation P
gamma 4 / r2 gamma E / m r 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
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Synchrotron radiation
Suppose we increase LEP beam energy (100 GeV) by
factor 5 E ? 500 GeV, in the same tunnel P
gamma 4 / r2 gamma increases by 5, so P
increases by 54 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!
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Synchrotron radiation
What about LHC? m_proton 2000
m_electron for same E, gamma_electron 2000
gamma_proton P_electron 20004
P_proton Even for LHC, E 70 LEP, each proton
loses only 5 keV per turn
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SLAC Linear Collider
c. 50 GeV per beam
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International Linear Collider
c. 250 GeV / beam
31 km
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Compact Linear Collider (CLIC)
Drive Beam Generation Complex
Main Beam Generation Complex
1.5 TeV / beam
Delahaye
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Concept for beam-driven Plasma Wake Field TeV
Linear Collider
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Concept of TeV ee- collider based on
laser-plasma acceleration
Wim Leemans and Eric Esarey, Physics Today, March
2009
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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

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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
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Resume of lecture 2

• Importance of accelerators for fundamental
  discoveries
• Why colliders how they work
• The Large Hadron Collider is amazing
• Future high-energy colliders

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