LARGE HADRON

COLLIDERat CERN

RAS, Nov 2008 Alan Barr University of Oxford

The

The building blocks of matter

CELLSTwentyper mm

DNA Five hundred

thousandper mm

Nucleus Five hundred

billionper mm

QuarksMore than onemillion billion

per mm

Extra magnification?

x 2 thousand

x 25 thousand

x 1 million

Electronmicroscope

Particle Accelerators

2 fm

< 1 am

50 μm

2 nm

Microscope

The new periodic table

Electron, e

d quark

Photon, γ

Gluon, gNot to scale!

Commonplace particles

u quark

Matter Particles

u

Quarks

d

c

s

t

b

Leptons

νe νμ ντ

e μ τ

Force carriers

W Z γg

Components and theory largely understood

Underlie all of physics, astronomy, chemistry, life!

Almost all extremely well tested

Not seen

h G

Several big unanswered questions at the scientific frontier…Several big unanswered questions at the scientific frontier…

Extraordinarily well tested

Where has all the anti-matter gone?

Matter and antimatter should have been created in equal amounts

Subtle differences between matter and anti-matter will be investigated at the LHC

High energy collisions create both in approximately equal amounts

Where are the anti-planets?

The dark side of the universe

96% of the universe is NOT made of atoms

Invisible matter dominatesLots of circumstantial evidence

Invisible mass

Visible mass

Bullet

Mass and the Higgs Boson

In this analogy the Higgs Bosonis a treacle-ball – something which allows us to see the treacle itself

Endows space with a kind of all-pervasive sticky-treacle

Interactions with this treacle gives mass to particles

They then travel slower than the speed of light

The Higgs Field

High energy collisions ought to make Higgs Bosons

Big questions

Where do the particles get their mass from?

Where has all the anti-matter gone?

What is dark matter made of?

What else is out there?

CERN European Laboratory for Particle Physics

Map © Google

• World’s largest particle physics laboratory• Joint venture started in 1954 • Multi-national laboratory on Swiss-French border• Collaborators include many UK universities

French Alps

Lake Geneva

Geneva

French Jura Mts

Blue Peter guide

Take some protons Lots of these in nature!

Make them move (very fast)

Bang them together It’s good to stand back at this point

Photograph the debris Your camera-phone may not be fast enough!

Foot on the accelerator…

2.. cmE Energy

v / c

Lorentz velocity factor

221

1

cv

Speed of light

Mass

Velocity factor

Note concerning “high energy”

Spark could jump 5000 km in air(~radius of The Earth)

The detectors are like digital camerasVery large

cathedral-sizedPrecise:

better than hair-width accuracyFast:

40 million snaps per second (Your camera-phone probably isn't up to this!)

Built by Collaborations: constructed by hundreds of physicists, technicians, engineers

Simulation

Switch on…CMS

LHCbALICE

… the beginning …

Physics output will take some time, but benefits seen already…

Physics output will take some time, but benefits seen already…