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…