The Large Hadron Collider: will it produce a Big Bang? - Dr Vincent Smith University of Bristol & UNSW Visiting Fellow
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The Large Hadron Collider: will it produce a Big Bang? Dr Vincent Smith University of Bristol & UNSW Visiting Fellow
The Large Hadron Collider:
will it produce a Big Bang?
● Introduction to CERN
● What do we know already?
● What might we find ?
● The LHC and the experiments
Introduction to CERN CERN: Conseil Européen pour la Recherche Nucléaire (European Organisation for Nuclear Research: 1954) Sometimes: European Laboratory for Particle Physics (In reality, not just European…) We are an International Organisation (like Nato, UN, etc)
CERN • Budget 2011: 1 112 million Swiss Francs • 20 Member States • Each member state pays in proportion to GDP • UK pays 15% (£100 million) per year • = £1.70 per person per year (2.70 AUD)
But CERN ‘users’ come from all over the world...
What do we do at CERN ? Fundamental research in particle physics: • Constituents of matter (and forces) • Origin and Structure of the Universe • Big Questions: What is the origin of mass, what is dark matter, what happened in the big bang, what happened to anti-matter…
Four Forces of Physics:
• (Gravity)
• Electromagnetism
• Strong Nuclear Force
• Weak Nuclear Force
Each has its carrier particles
9
• Why is there such a range of particle masses?
Why do they have mass at all?
Possible solution: Higgs mechanism…Have we found all the particles there are? Galactic rotation curves: visible matter is only a fraction of the total, the remainder is ‘Dark Matter’ (and Dark Energy.) Can we create Dark Matter particles in the lab ?
• Are quarks and leptons related?
Are they made of
even tinier particles?
•Are the different forces related ?
Do they become a single force
at very high energy ?• What happened
in the Big Bang ?
A new state of matter
at extremely high
temperature?
13• What happened to all the Antimatter ?
Matter and antimatter annihilate
to form pure energy …
14• What other surprises does Nature have for us?
Unknown unknowns…
15How do we do our research ?
Accelerators: Put lots of energy into particles
Colliders: Turn energy into matter: E = mc2
Detectors: Identify and measure particles,
Computers: To understand what happened:
infer the properties of the parent (heavy) particles.In the LHC particles are accelerated
to 7 000 000 000 000 volts
p
pMethods of Particle Physics
1) Concentrate energy on
particles (accelerator)
2) Collide particles (recreate
conditions after Big Bang)
3) Identify created particles in
Detector (search for new clues)
18CERN's mission:
Accelerator chain
to at CERN,
build a complex
particle business
accelerators
19CERN's mission:
The Large Hadron Collider (LHC)
to build is theaccelerators
particle most powerful
instrument ever built to investigate particle properties.
• Four gigantic
underground caverns to
host the huge detectors
• The highest energy of
any accelerator in the
world
• The most intense
beams of colliding
particles
• It operates at a
temperature colder than
outer spaceSome LHC statistics
Proton beam energy: 7 TeV + 7 TeV (3.5 + 3.5 TeV this year and next)
(Proton mass = 1 GeV)
Speed of Protons: 99.999 999 1 % of speed of light
Stored energy in beam: 300 MJ (eventually; a few MJ today)
Magnetic field: 8.36 Tesla
Cooled by 700,000 litres of liquid Helium at 1.9K
(superfluid…)
Dipole length: 15 m, mass 35 T (1232 of them + ~2500 others)
Wire is Niobium-Titanium alloy, carrying 12kA at full field.
There are 40,000 pipe joints.The Detectors
General-Purpose Detectors: Atlas and CMS ● Detect and measure all particles from the collision (‘Hermetic’ construction) ● Tracker (and magnet) to measure direction and momentum of charged particles ●‘Calorimeters’ to measure energy of: (1) Electromagnetic and (2) Hadronic particles ● Muon chambers ● ‘Missing’ Energy
The CMS experiment at point 5
CMS Detector at LHC
One of 5 sections of the CMS superconducting coil
Building the CMS experiment for the LHC
The CMS magnet has about 10 000 tonnes of iron
(more than the Eiffel tower)
32The CMS Detector before closing
7 TeV collision event recorded in CMS
Higgs signature at the LHC
In the LHC particles collide about 600 million times/second
We expect only 1 Higgs in
1,000,000,000,000 events 35‘Possible’ Higgs event: H → Z Z → 2e + 2μ Electrons ‘shower’ in calorimeter, muons penetrate to outer detectors.
Higgs event into two Photons
Higgs ‘discovery’ or ‘exclusion’ ?
(Part of ) The CERN Computer Centre
(20 000 PCs)The GRID: a possible solution to CERN
The LHC Computing GRID (LCG)needs
computing is a project co-funded by
the European Union. Its objective is to build the next
generation computing infrastructure providing intensive
computation and analysis.
Uni x Lab m
regional group
CERN Tier 1
Uni a
Lab a UK
USA
France
The LHC
Tier 1
Tier3 Uni n
physics
Tier2 Computing
……….
Italy
Centre CERN Tier 0
department
Desktop
γ ………. Germany
Lab b Lab c
β physics group
Uni y Uni b
α
40Why do we do it ?
(and who benefits?)
• Basic Research (We seek answers to fundamental questions about the
constituents of matter, the origin of the universe, etc.)
• Advanced technology (Pushing forward the frontiers of technology
and engineering.)
• Training (Education and experience for the young scientists and
engineers who will be the experts of tomorrow.)
• International cooperation (Unites about 9,000 physicists coming
from all over the world.)CERN: where the Web was born!
How to x-ray a lorry ! Using wire chambers, invented at CERN
Medical applications of Particle Physics …
44Thanks for listening! Proton collisions at 3.5 + 3.5 TeV this year and next… You can watch and for further news…
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