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Re-creating the Big BangExperiments at the Large Hadron Collider
Dr Cormac O’ Raifeartaigh (WIT)
Albert Einstein
Ernest Walton
Overview
I What
II Why
III How
IV A brief history of atoms
V Expectations
I The Large Hadron Collider
A particle accelerator
‘Atom smasher’
Particles created
Detected
LHC at CERN, Geneva
How
High speed proton beams
Opposite directions - collisions
Huge energy of collision
Create short-lived particles
Detection and measurement E = mc2
HOW
27 km
Energy: 14 TeV
Low temp: 1.6 K
Ultra high vacuum
Why
Explore fundamental constituents of matter
Investigate forces that hold matter together
Glimpse of early universeHighest energy since BB
Are the forces of the universe related ?
•Gravity caused by sun’s mass
Newton (1642-1727)
•Planet orbits due to gravity
Newton’s gravity
2r
MmGF
•Terrestrial gravity due to earth’s mass
Four forces of nature Force of gravityHolds cosmos togetherLong range
Electromagnetic force Holds atoms together
Strong nuclear force: holds nucleus together
Weak nuclear force: radioactivity
The atom
A brief history of atoms
Democritus (600 BC): matter made of atoms
Dalton (19th ct): Mendeleev (19th ct):
chemical reactions
A brief history of atoms
Maxwell (19th ct): atomic theory of gases
Einstein: (1905): Brownian motion due to atoms?
Perrin (1908): verified
Brownian motionEinstein Perrin
The atomic nucleus
•Most projectiles through
•A few deflected backwards
•Atom has nucleus
•Electrons outside
Rutherford (1911)
Nuclear model of the atom
nNu
•Nucleus (+ve): •Electrons (-ve): orbiting •Force: electromagnetic
•Protons (1909)•Nucleus (1911)•Neutrons (1932)?
Atom
Nucleus
Nuclear force: stronger than electromagnetic?
Splitting the nucleus
Cockcroft and Walton: particle accelerator
Particles used to split the nucleus (1932)
Nobel prize (1956)
H + Li = He + He
Verified mass-energy (E= mc2)Verified quantum tunnelling
Nuclear fission
Meitner, Hahn: nuclear fission
Energy released
•Chain reaction•Nuclear bomb
•Nuclear power•Nuclear power stations
New particles
Cosmic rays New particle accelerators
cyclotron
Particle Zoo
Over 100 particles
The quark model
New periodic tableNew fundamental particle
Proton not fundamental Inner structure
Symmetry argumentsQuarks
Murray Gellmann
Quarks and leptons
Six different quarks(u,d,s,c,t,b)
Six leptons
(e, μ, τ, υe, υμ, υτ)
Particles of matter: fermions
Two extra generations
The Standard Model
Matter: leptons and quarks
Force carriers: bosons
EM + weak = electroweak
Strong force = quark force
Higgs fieldParticle massesHiggs boson
LHC: expectations
Higgs boson
120-180 GeV
Set by mass of top quark, Z boson
Explain masses for other particles
Beyond the standard model
Unification of 3 forces
Grand unified theory
Supersymmetry
Supersymmetric particles?
Unification of 4 forces
Theory of everything
String theory
Extra dimensions
LHC and cosmology
√ 1. Exotic particles
√ 2. Unification of forces
3. Nature of dark matter?
4. Missing antimatter?
LHC = photo of early U
3. Summary
Higgs bosonClose chapter on SM
Supersymmetric particlesOpen chapter on unification
WIMPSExplain Dark Matter
Unexpected particlesRevise theory
Epilogue: CERN
World centre for particle physics
20 member states
10 associate states
Ireland not a member
No particle physics in Ireland
Organization for Nuclear research