Transcript NLC - Nanyang Technological University

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
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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
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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
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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.
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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
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Want to see what matter is made of
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Smash matter apart and look for the building blocks
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Take small pieces of matter:
accelerate them to very high energy
crash them into one another
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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 Js
p = 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?
For speeds
well below
60 mph
stationary
30 mph
30 mph
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?
For the same
physics,
14,000 times
the energy
stationary
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
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Each beam contains 3000 ‘bunches’ of protons
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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
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27km tunnel is 50 – 150 m below ground
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Two beams of protons circulating in opposite directions
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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)
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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. 10**34 / cm**2 / 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 / r**2
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 / 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!
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Synchrotron radiation
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
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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
Philip Burrows
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IoP Divisional Conference, Glasgow 6//4/11
Concept for beam-driven Plasma Wake Field TeV
Linear Collider
RF gun
Drive beam accelerator
RF separator
bunch compressor
Drive beam distribution
Beam Delivery and IR
PWFA cells
DR e-
main beam einjector
PWFA cells
main beam e+
injector
DR e+
Concept of TeV e+e- collider based on laser-plasma
acceleration
Wim Leemans and Eric Esarey, Physics Today, March 2009
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
• 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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