2. • The Large Hadron Collider (LHC) is
the world's largest and highest-energy particle
accelerator. It was built by the European
Organization for Nuclear Research (CERN) over a
ten year period from 1998 to 2008, with the aim of
allowing physicists to test the predictions of
different theories of particle physics and high-
energy physics, and particularly for the existence of
the hypothesized Higgs boson and of the large
family of new particles predicted
by supersymmetry. The LHC is expected to address
some of the most fundamental
questions of physics, advancing the understanding
of the deepest laws of nature. It contains six
detectors each designed for specific kinds of
3.
4.
5. • The LHC lies in a tunnel 27 kilometres (17 mi)
in circumference, as deep as 175 metres (574 ft)
beneath the Franco-Swiss border near Geneva,
Switzerland. Its synchrotronis designed
to collide opposing particle beams of
either protons at up to 7 teraelectronvolts (7
TeV or 1.12 microjoules) per nucleon,
or lead nuclei at an energy of 574 TeV (92.0 µJ)
per nucleus (2.76 TeV per nucleon).It was built
in collaboration with over 10,000 scientists and
engineers from over 100 countries, as well as
hundreds of universities and laboratories.
6. The LHC experiments
• The six experiments at the LHC are all run by
international collaborations, bringing together
scientists from institutes all over the world. Each
experiment is distinct, characterised by its unique
particle detector.
• The two large experiments, ATLAS and CMS, are
based on general-purpose detectors to analyse the
myriad of particles produced by the collisions in the
accelerator. They are designed to investigate the
largest range of physics possible. Having two
independently designed detectors is vital for cross-
confirmation of any new discoveries made.
7. The LHC experiments
• Two medium-size
experiments, ALICE and LHCb, have
specialised detectors for analysing the LHC
collisions in relation to specific phenomena.
• Two further experiments, TOTEM and LHCf, are
much smaller in size. They are designed to focus on
"forward particles" (protons or heavy ions). These
are particles that just brush past each other as the
beams collide, rather than meeting head-on
8. The LHC experiments
• The ATLAS, CMS, ALICE and LHCb detectors
are installed in four huge underground caverns
located around the ring of the LHC. The
detectors used by the TOTEM experiment are
positioned near the CMS detector, whereas those
used by LHCf are near the ATLAS detector.
9. Detector Description
ATLAS
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.
CMS
the other general purpose detector will, like ATLAS, hunt for the Higgs
boson and look for clues to the nature of dark matter.
ALICE
is studying a "fluid" form of matter called quark–gluon plasma that
existed shortly after the Big Bang.
LHCb
equal amounts of matter and antimatter were created in the Big Bang.
LHCb will try to investigate what happened to the "missing" antimatter.
10.
11. Inaugural tests
• 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.
12. Inaugural tests
• The LHC successfully completed its 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.
13.
14.
15.
16. 2008 quench incident
• On 19 September 2008, a magnet
quench occurred in about 100
bending magnets in sectors 3 and 4, causing a
loss of approximately six tonnes of liquid
helium, which was vented into the tunnel, and a
temperature rise of about 100 kelvin in some of
the affected magnets. Vacuum conditions in the
beam pipe were also lost, and mechanical
damage was caused.
17. 2008 quench incident
• Shortly after the incident CERN reported that the
most likely cause of the problem was a faulty
electrical connection between two magnets, and
that – due to the time needed to warm up the
affected sectors and then cool them back down to
operating temperature – it would take at least two
months to fix.Subsequently, CERN released a
preliminary analysis of the incident on 16 October
2008, and a more detailed one on 5 December
2008.Both analyses confirmed that the incident was
indeed initiated by a faulty electrical connection. A
total of 53 magnets were damaged in the incident
and were repaired or replaced during the winter
shutdown.
18. 2008 quench incident
• In the original timeline of the LHC commissioning,
the first "modest" high-energy collisions at a center-
of-mass energy of 900 GeV were expected to take
place before the end of September 2008, and the
LHC was expected to be operating at 10 TeV by the
end of 2008.However, due to the delay caused by
the above-mentioned incident, the collider was not
operational until November 2009.Despite the delay,
LHC was officially inaugurated on 21 October 2008,
in the presence of political leaders, science ministers
from CERN's 20 Member States, CERN officials,
and members of the worldwide scientific
community.
19. 2008 quench incident
• Most of 2009 was spent on repairs and reviews
from the damage caused by the quench incident,
along with two further vacuum leaks identified
in July 2009 which pushed the start of
operations to November of that year.
21. Full operation
• The first proton run ended on 4 November 2010. A
run with lead ions started on 8 November 2010, and
ended on 6 December 2010, allowing the ALICE
experiment to study matter under extreme
conditions similar to those shortly after the Big
Bang.
• CERN has declared that the LHC will run through to
the end of 2012, with a short technical stop at the
end of 2011. The energy for 2011 will be 3.5 TeV per
beam. In 2013 the LHC will go into a long shutdown
to prepare for higher-energy running starting in
2014.
23. Safety of particle collisions
• The experiments at the Large Hadron Collider
sparked fears among the public that the particle
collisions might produce doomsday phenomena,
involving the production of stable microscopic black
holes or the creation of hypothetical particles
called strangelets .Two CERN-commissioned safety
reviews examined these concerns and concluded
that the experiments at the LHC present no danger
and that there is no reason for concern ,a conclusion
expressly endorsed by the American Physical
Society.
25. Cost of this experiment
• With a budget of 7.5 billion euros (approx. $9bn
or £6.19bn as of Jun 2010), the LHC is one of
the most expensive scientific instruments ever
built.The total cost of the project is expected to
be of the order of 4.6bn Swiss francs (approx.
$4.4bn, €3.1bn, or £2.8bn as of Jan 2010) for
the accelerator and SFr 1.16bn (approx. $1.1bn,
€0.8bn, or £0.7bn as of Jan 2010) for the CERN
contribution to the experiments.
26. Cost of this experiment
• The Large Hadron Collider gained a considerable
amount of attention from outside the scientific
community and its progress is followed by most
popular science media. The LHC has also sparked the
imaginations of authors of works of fiction although
descriptions of what it is, how it works, and projected
outcomes of the experiments are often only vaguely
accurate, occasionally causing concern among the
general public.
