Jan 12, 2016
What are we made of ?
Neutrinos
Building a Particle Collider
The ring is 27km round and on average 100m underground
CERN – LEP, LHC
We need particles…
The hydrogen source for protons at the LHC…
We need to accelerate them…
Van de Graff Generator
+ Plasma Ball
LHC RF cavityLHC RF cavity
We need to control them…
Cathode ray tube + magnets
Accelerator Physics
Electron positron annihilation to a photon allows us to convert their energy to look for all the particles that make up nature
E = m c 2
The Large Hadron Collider collides the nuclei of atoms with 10 times higher energy than has previously been achieved (14 TeV)
1232, 35 ton, superconducting dipole magnets accelerate ions and focus them into bunches for collision
36,000 tons of coolant below 2K!
LHC
Proton-Proton collisions (hydrogen atom nuclei)
100 billion protons per bunch
20 collisions per crossing
1 crossing every 25ns
600 million collisions per second
14 TeV centre of mass energy
To store all collision data would involve storing 10 Petabytes of data a year ie a 20km high stack of CDs… more than can be made
Detection…
Cloud Chamber
Calorimeters…• Crystal, glass,
liquid• Acts as absorber
and scintillator• Light detected
by photodetector
• E.g. PbWO4
vertex detectors look for inflight decays of particles…
What have we found?
What have we found?
Why do otherwise identical particles have different masses?
There must be a new force that interacts differently with the muon and electron… its quanta are the higgs boson… more in the final lecture…