The Large Hadron Collider and Beyond

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The Large Hadron Collider and Beyond
Steve King, University of Southampton,
Masterclass, 24th March, 2010
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Why High Energy?
There are three reasons

1. The resolving power of a microscope is limited by
   the wavelength of the light.

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2. Einstein taught us that
So
high energy is equivalent to large mass. With
high energies we are able to produce very heavy
particles.
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3. Boltzmann taught us that so
high energy means high temperature
where is Boltzmanns constant. In the
early Universe, just after the big bang, the
universe was very small and very hot.
So high energy physics
teaches us about the early Universe.
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What have we learned from High Energy Physics?
- Matter is made of particles (particle physics)
To understand this, take an apple and a knife,
and cut the apple in half once. Then cut one half
in half again. Then continue the process. After
some number of cuts you will arrive at a single
atom.
Question how many cuts are required?
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The nucleus of the atom is positively charged
It is made of protons (p) and neutrons (n)
The protons and neutrons are made of charged
quarks
The quarks also carry a new colour charge
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I think I finally understand atoms
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Nothing lasts for ever
The (free) neutron is radioactive and beta decays
after 15 minutes into proton, electron and
neutrino (electron-like neutral particle)
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Neutrinos from the Sun
Question How many neutrinos from the Sun are
passing through your fingernail in one second?
Answer 40 billion! day and night since
neutrinos can pass right through the Earth
without interacting
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The four forces of Nature
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Quarks and Leptons
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The mystery of spin
All observed elementary particles have spin i.e.
spinning angular momentum like a spinning top In
quantum mechanics the basic unit of angular
momentum is Plancks constant h divided by 2?
Photons and gluons have one unit of spin e.g.
polarization of light is due to the photon
spin Quarks and leptons have half a unit of
spin e.g. In chemistry each s-orbital can only be
occupied by at most two electrons, spin-up and
spin-down. N.B. Without spin any number of
electrons could pile into the lowest energy
s-orbital and Chemistry AS level would not exist
unfortunately you not exist either!
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What is the origin of the particle masses?
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The Higgs Boson
In the Standard Model the origin of mass is
addressed using a mechanism named after the
British physicist Peter Higgs.
This predicts a spinless particle Higgs boson
According to Higgs, space is filled with a new
type of field analagous to magnetic or electric
fields
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The CERN Large Hadron Collider (LHC)
Atlas
particle_event_full_ns.mov
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Pictorial History of the LHC
10th September 2008 - LHC switched on
BBC devote a whole day of
coverage to Big Bang day -Soothsayers predict
the end of the World
- Scientists at CERN celebrate

Too many late nights?
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Pictorial History of the LHC
19th September 2008 LHC explosion due to bad
soldering joint between two magnets repairs
took 14 months
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Pictorial History of the LHC
20th November 2009 LHC switched on again 23rd
November 2009 first LHC proton- proton
collisions
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Pictorial History of the LHC
16th December 2009 LHC routine shut down for
Christmas 28th February 2010 LHC switched on
again 19th March 2010 (last Friday) LHC proton
beams at 3.5 TeV
E3.5 TeV
mc20.938 GeV
World land speed record for protons
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The CERN Large Hadron Collider (LHC) will next
Tuesday collide protons on protons at energy of
3.5 TeV 3.5 TeV 7 TeV
LHC plans to run at 7 TeV for 18-24 months to
acquire as many collision events as possible
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What will the LHC discover? (apart from the Higgs)
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Supersymmetry ?
All particles in nature are either fermions or
bosons.
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Could dark matter observed in the collisions of
galaxy clusters be the photino? LHC will see
it
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SUSY permits a unification of forces
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string1.avi
Strings live in 11 dimensions
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What if no Higgs or SUSY is discovered?
My personal best bet for the first discovery at
the LHC is a heavier version of the Z boson
called a Z-primed Other possibilities include a
fourth family, composite quarks and leptons,
extra dimensions, technicolour, black holes
(environmentally friendly), extra exotic
particles with weird charges and colours,
etc.. Nightmare scenario one Higgs boson and
nothing else! I DONT BELIEVE THIS WILL
HAPPEN More likely LHC will discover something
no-one has thought of let us hope that whatever
is found will be of great benefit humanity I
think there is every chance
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What has the LHC done for us?

• Many technological and medical spin-offs
• Medical imaging chips developed at CERN
• Software developed at CERN used in medical
  physics
• World Wide Web developed at CERN
• Many top engineers and scientists trained at CERN
• Oxford positron systems founded by CERN physicst
• - Young people attracted into science by CERN
  physics