THE

LARGE
HADRON
COLLIDER
By:
Ashutosh
Hema kashyap
Neeti bisht
 World’s largest particle physics laboratory
 European organization for nuclear reseach.
 Joint venture started in 1954
 Multi-national laboratory on Swiss-French border
 Collaborators include many UK universities
 Large Designed
Designed and
and built
built
Hadron over
over last
last two
two decades
decades
Collider

Turns
Turns onon
this Will
Will help
help to
to answer
answer
this year
year
some
some of
of the
the deepest
deepest
mysteries
mysteries inin science
science
 LHC is the world’s largest and highest-energy particle
accelerator.
 Based on proton –proton collision.
 It is designed to collide opposing particle beams of either
protons at an energy of 7 Tev per particle or lead nuclei at an
energy of 574 Tev per nucleus.
 French Alps
Geneva
Lake Geneva French Jura Mts

Lies in a tunnel 27 km in circumference

Beneath the Franco-Swiss border near
Geneva,Switzeraland
At a depth ranging from 100 to 175 m
underground
 help to answer the most fundamental particles  in physics
 basic laws governing the interactions and forces among the elementary objects
 the deep structure of space and time, especially regarding the intersection of 
quantum mechanics and general relativity, where current theories and
knowledge are unclear or break down altogether. These issues include, at least:
 Is the Higgs mechanism for generating  elementary particle masses
 via electroweak symmetry breaking indeed realised in nature?
 it is anticipated that the collider will either demonstrate or rule out the
existence of the Higgs boson, completing the Standard model.
 Is supersymmetry, an extension of the standard model and poincare’s
Symmetry, realised in nature, implying that all known particles
have supersymmetry parterners. These may clear up the mystery of Dark
Matter.
 Are there extra dimensions as predicted by various models inspired by string
theory, and can we detect them?
 The 3.8-metre (12 ft) wide concrete-lined tunnel,
constructed between 1983 and 1988, was formerly used
to house the Large Electron–Positron Collider.
 It crosses the border between Switzerland and France at
four points, with most of it in France.
 Surface buildings hold ancillary equipment such as
compressors, ventilation equipment, control electronics
and refrigeration plants.
 The collider tunnel contains two adjacent parallel beam
pipes that intersect at four points, each containing a
proton beam, which travel in opposite directions around
the ring.
 Some 1,232 dipole magnets keep the beams on
their circular path, while 392 quadrupole magnets
 are used to keep the beams focused .
 In order to maximize the chances of interaction
between the particles in the four intersection
points, where the two beams will cross.
 In total, over 1,600 superconducting magnets are
installed, with most weighing over 27 tonnes.
Approximately 96 tonnes of liquid helium is needed
to keep the magnets at their operating
temperature of 1.9 K (−271.25 °C), making the LHC
the largest cryogenic facility in the world at liquid
helium temperature.
 Conti….
 It will take less than 90 microseconds (μs) for a proton to travel once around the
main ring – a speed of about 11,000 revolutions per second.
 Rather than continuous beams, the protons will be bunched together,
into 2,808 bunches, so that interactions between the two beams will take place
at discrete intervals never shorter than 25 nanoseconds (ns) apart.
 However it will be operated with fewer bunches when it is first commissioned,
giving it a bunch crossing interval of 75 ns.
 Prior to being injected into the main accelerator, the particles are prepared by a
series of systems that successively increase their energy.
 The first system is thelinear particle accelerator LINAC 2 generating 50-MeV
protons, which feeds the Proton Synchrotron Booster (PSB).
 There the protons are accelerated to 1.4 GeV and injected into the 
Proton Synchrotron (PS), where they are accelerated to 26 GeV.
 Finally the Super Proton Synchrotron (SPS) is used to further increase their
energy to 450 GeV before they are at last injected (over a period of 20 minutes)
into the main ring. Here the proton bunches are accumulated, accelerated (over
a period of20 minutes) to their peak 7-TeV energy, and finally circulated for 10
to 24 hours while collisions occur at the four intersection points.
 Very large:cathedral-sized
 Precise:better than hair-width accuracy
 Fast:40 million snaps per second
 Built by Collaborations: constructed by hundreds
of physicists, technicians, engineers
 Six detectors have been constructed at the LHC, located
underground in large caverns excavated at the LHC's
intersection points.
 Two of them, the ATLAS experiment and the 
Compact Muon Solenoid (CMS), are large, general
purpose particle detectors.[20] 
 A Large Ion Collider Experiment (ALICE) and LHCb have
more specific roles and the last two TOTEM and LHCf are
very much smaller and are for very specialized research.
The BBC's summary of the main detectors is
Four detectors at different points around the ring
reconstruct the debris from the collisions
One of two general purpose detectors. ATLAS will be used to look
for signs of new physics, including the origins of mass and extra
dimensions.
will study a "liquid" form of matter called 
quark–gluon plasma that existed shortly after the 
Big Bang.
the other general purpose detector will, like ATLAS, hunt for
the Higgs boson and look for clues to the nature of dark
matter.
equal amounts of matter and antimatter were created
in the Big Bang. LHCb will try to investigate what
happened to the "missing" antimatter.
 Take some protons
You can get these
from the tap if you like
 Make them move
(very fast)
 Bang them together
It’s good to stand
back at this point
 Photograph the Hydrogen Electron Proton
debris
Your camera-phone may
not be fast enough!
At four places the beams
intersect
Simulated event of the
collision of two protons in
a particle accelerator
viewed along the beam
pipe. The colors of the
tracks emanating from
the center show the
different types of
particles emerging from
the collision
 Electric waves speed particles up

Magnets bend them

in a circle
 The energy density and temperature that will
be made available inthe collisions at the LHC
are similar to those that existed a few
momentsafter the Big Bang. In this way
physicists hope to discoverhow the Universe
evolved.
Commonplace particles Matter Particles
Electron, e Quarks Leptons
u quark
u c t e μ τ
Photon, γ d s b νe νμ ντ
d quark Force carriers Not seen
Gluon, g
Not to scale!

g W Z γ h G

 Components and theory largely understood

 Underlie all of physics, astronomy, chemistry, life!

 Almost all extremely well tested

 The first beam was circulated through the collider on the
morning of 10 September 2008.
 CERN successfully fired the protons around the tunnel in stages,
three kilometres at a time.
 The particles were fired in a clockwise direction into the
accelerator and successfully steered around it at 10:28 local time.
 The LHC successfully completed its first major test: after a series
of trial runs, two white dots flashed on a computer screen
showing the protons travelled the full length of the collider.
 It took less than one hour to guide the stream of particles around
its inaugural circuit.
 CERN next successfully sent a beam of protons in a
counterclockwise direction, taking slightly longer at one and a
half hours due to a problem with the cryogenics with the full
circuit being completed at 14:59.
Normal: Made from atoms
Includes stars,
planets, people…
Dark matter: Unknown substance
(not atoms)
May be a “fat cousin”
of normal light
Hope to make & study
it at the LHC
Dark energy: Even weirder!
 Black holes possess gravitational fields so
strong that nothing can escape them, not
even light. They normally form when the
remains of a dead star collapse under their
own gravity, squeezing their mass together.
Although black holes can't be seen,
astronomers infer their existence by the 
gravitational effects they have on gas and
stars around them.
 Scientists could generate a black hole as
often as every second when the world's most
powerful particle accelerator comes online in
2007.
 This potential "black hole factory" has raised
fears that a stray black hole could devour our
planet whole.
 Still, any fears that such black holes will consume
the Earth are groundless, Landsberg said.
 "Still, let's assume that even if Hawking is a genius,
he's wrong, and that such black holes are more
stable," Landsberg said. Nearly all of the black
holes will be traveling fast enough from the
accelerator to escape Earth's gravity. "Even if you
produced 10 million black holes a year, only 10
would basically get trapped, orbiting around its
center," Landsberg said.
 Now: finishing construction
Commissioning equipment
(Access still possible)

End 2007: End 2008?:

Mid 2008:
switch on First results
physics analysis
 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?

Various exotics considered…
 New forces of nature
 Extra dimensions of space
 Microscopic black holes
Suggested by e.g. string theory

The
The LHC
LHC experiments
experiments can
can look
look for
for all
all of
of
these
these..
Also
Also sensitive
sensitive to
to something
something “completely
“completely different”
different”