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What is the LHC?
• The most powerful particle accelerator in the world.
• A synchrotron (ring-shaped particle accelerator)
• Built by the European Organization for Nuclear Research (CERN)
• A part of the CERN accelerator complex
History of the LHC
• The LEP (Large Electron-Positron Collider)– Built in the tunnels the LEP used to occupy
• Approved by CERN Council in 1994• Built 1996- 2008• Opened April 5th 2008• Technical difficulties–Magnetic failures and a helium leak
• 2010 first successful experiment
What does it do?
• It accelerates two beams of hadrons at 99% the speed of light.– Particles of Matter
• Uses 9,600 magnets to collide the two beams at six sites around its circumference.
• Observes and studies the collisions.
What it’s looking for…
• A mini Big Bang– Atomic subparticles– Matter v. Antimatter
• Dark Matter• The Standard Model– Higgs Boson Particle
• String Theory– 11 dimensions– Supersymmetry
Six Collision Sites
ATLAS• A Toroidal LHC ApparatuS• 46m long, 25m tall, 25m
wide• Inner tracker
– Detect & analyze momentum
• Calorimeter– Measures energy by
absorption, shows path
• Moun spectrometer– Measures momentum of
particles too heavy to be caught by calorimeter
CMS• Compact Moun
Solenoid• General purpose• Contained inside
solenoid magnet– Field is 100,000 times
stronger than Earth’s
Six Collision Sites cont.
ALICE• A Large Ion Collider
Experiment• Studies the collisions
of iron ions• Moun spectrometer• Time Projection
Chamber (TPC)– Tracks particle
trajectories
LHCb• Large Hadron Collider
beauty• Search for antimatter
– Beauty/bottom quarks
• 20 meters of detectors around the site to catch the quarks
The Two Small Collision Sites
TOTEM• TOTal Elastic and
diffractive cross section Measurement
• Measures the size of protons
• Measures luminosity (how precisely an accelerator produces collisions)
LHCf• Large Hadron Collider
forward• Stimulates cosmic
rays• Tries to make
experiments where naturally occurring cosmic rays can be observed and studied
• 27 km circumference• 100 m underground• 8 arches, 8 insertions• Insertions- long
straight sections, control coming and going of particles– Injection– Beam dumping– Beam cleaning
• 3 vacuum systems– Beam vacuum– Insulation for
cryomagnets– Insulation for helium
distribution line
How It Works
Magnets•9,600 magnets•Guides the particle beams into collisions and through insertions.•3 Kinds
•Quadrupole- focuses beam•Accelerating Cavities- accelerate particles and keep them at constant speed•Dipole- keep the beams going in a circle
•8.33 T
Cooling System
• Designed so that the magnets can conduct electricity with almost no resistance and generate a high enough magnetic field.
• 120 tons of super fluid helium
• 5 cryogenic ‘islands’• Colder than outer
space: 1.9 K (-456.25 F)
Helium is cooled to 80 K, using 10,000
tons of liquid nitrogen.
Helium is cooled to 4.5 K, using refrigerator
turbines and is injected to the
magnets.
Refrigerator cools magnets further down, to 1.9 K.
Strip electrons from hydrogen atoms or lead ions to produce protons.
Protons enter LINAC 2 then the PS Booster. • Use radio frequency cavities to accelerate the protons to
form beams.• Control is transferred from the radio-frequency electric
fields to the magnets.
Sent to the Super Proton Synchotron (SPS).• Accelerated and divided into bunches• 2808 bunches in a beam, 1.1 x 1011 protons in a bunch.
Then takes 20 minutes for beams to reach top speed of 11,245 trips around the LHC per second.
Beams are positioned to collide at one of the six collision sites.
Particle Process
Collision Results
• Quarks- subatomic particles• Gluon- mitigating force• Photons- particles of light• Positrons- the anti-particles to
electrons• Muons- negatively charged, heavier
version of electrons
LHC Computing Grid
Tier 0CERN’s computing system
Processes information and divides it into chunks for the other two tiers.
Tier 112 sites in various countries
Receives data over dedicated computer connections at 10 gigabytes per second.
Divides the information again.
Tier 2Thousands of computers at universities all over
the world.Receives data through standard network
connection.Processes and analyzes the data.
Sends data back through the tiers to CERN.
•150 million sensors in the LHC•700 megabytes of data per second•15 petabytes per year•2001- EDG (European Data Grid project)•2004- EGEE (Enabling Grid for E-sciencE)•Divides the data into chunks to be analyzed separately•Uses midware•Uses identification and authorization procedures to keep the information safe.
Question 1
What does LHC stand for?1. Luminosity Higgs Controller2. Large Higgs Chamber3. Low Helium Cryomagnet4. Large Hadron Collider
Question 3
What are the names of the six detector sites?
1. CMS, ALICE, TPS, TOTEM, LEP, LHCb2. LHCf, LEP, CMS, ATLAS, LHCb, SPS3. ATLAS, CMS, ALICE, LHCb, TOTEM,
LHCf4. EDG, ATLAS, SPS, LEP, LHCf, CMS
Question 4
What does the LHC do?1. Measures momentum of particles too
heavy to be caught by calorimeter.2. Guides the particle beams into
collisions and through insertions.3. Collides two beams of particles.4. Measures energy of particles through
absorption.