What is Large Hadron Collider?
1.
The Large Hadron Collider (LHC) is a particle accelerator which will probe deeper into matter than ever before. Due to switch on in 2007, it will ultimately collide beams of protons at an energy of 14 TeV . Beams of lead nuclei will be also accelerated, smashing together with a collision energy of 1150 TeV.
A TeV is a unit of energy used in particle physics. 1 TeV is about the energy of motion of a flying mosquito. What makes the LHC so extraordinary is that it squeezes energy into a space about a million million times smaller than a mosquito.
Housed 100-kilometers below the earth, the LHC is currently being built by CERN.
The Large Hadron Collider makes mini big bangs.
2.
A device that when used has the potential to create miniature black holes. Physicist have assured us that this is of no concern, though, for two reasons. One is that these black holes are supposed to evoporate due to Hawking Radiation, which is an unobserved theory. And the other is that if the LHC is capable of producing black holes, cosmic rays should produce miniature black holes frequently when they collide with the atmosphere, which totally ignores the fact that these natural miniature black holes would have velocities much greater than the Earth's escape velocity. So there is a distinct possibility that when this collider fires up in 2007, the Earth could be doomed to be slowly accreted by miniature black holes at the center of the earth. However, you can rest assured that the physicists that are willing to gamble with the functional existence of Earth on the basis that this scenario will not happen do not seem to care.
Firing up the Large Hadron Collider without observational evidence of Hawking Radiation is like not putting enough life boats on the Titanic.
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3.
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator complex, intended to collide opposing beams of protons (one of several types of hadrons) with very high kinetic energy. Its main purpose is to explore the validity and limitations of the Standard Model, the current theoretical picture for particle physics. It is theorized that the collider will confirm the existence of the Higgs boson, the observation of which could confirm the predictions and missing links in the Standard Model, and could explain how other elementary particles acquire properties such as mass.
The LHC was built by the European Organization for Nuclear Research (CERN), and lies underneath the Franco-Swiss border between the Jura Mountains and the Alps near Geneva, Switzerland. It is funded by and built in collaboration with over eight thousand physicists from over eighty-five countries as well as hundreds of universities and laboratories. The LHC is operational and is presently in the process of being prepared for collisions. The first beams were circulated through the collider on 10 September 2008, and the first high-energy collisions are expected to take place after 6-8 weeks.
The LHC
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 an additional 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, making the LHC the largest cryogenic facility in the world at liquid helium temperature.
Superconducting quadrupole electromagnets are used to direct the beams to four intersection points, where interactions between protons will take place.
Superconducting quadrupole electromagnets are used to direct the beams to four intersection points, where interactions between protons will take place.
Once or twice a day, as the protons are accelerated from 450 GeV to 7 TeV, the field of the superconducting dipole magnets will be increased from 0.54 to 8.3 tesla (T). The protons will each have an energy of 7 TeV, giving a total collision energy of 14 TeV (2.2 μJ). At this energy the protons have a Lorentz factor of about 7,500 and move at about 99.999999% of the speed of light. It will take less than 90 microseconds 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. When the collider is first commissioned, it will be operated with fewer bunches, to give a bunch crossing interval of 75 ns. The number of bunches will later be increased to give a final bunch crossing interval of 25 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 the linear particle accelerator Linac 2 generating 50 MeV protons, which feeds the Proton Synchrotron Booster. 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 of 20 minutes) to their peak 7 TeV energy, and finally stored for 10 to 24 hours while collisions occur at the four intersection points.
The LHC will also be used to collide lead (Pb) heavy ions with a collision energy of 1,150 TeV. The Pb ions will be first accelerated by the linear accelerator Linac 3, and the Low-Energy Injector Ring will be used as an ion storage and cooler unit. The ions then will be further accelerated by the PS and SPS before being injected into LHC ring, where they will reach an energy of 2.76 TeV per nucleon.
Detectors
The Large Hadron Collider's (LHC) CMS detectors being installed.
The Large Hadron Collider's (LHC) CMS detectors being installed.
Six detectors are being 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.
* ATLAS – one of two so-called 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 – will study a "liquid" form of matter called quark-gluon plasma that existed shortly after the Big Bang.
* LHCb – equal amounts of matter and anti-matter were created in the Big Bang. LHCb will try to investigate what happened to the "missing" anti-matter.
Purpose
A Feynman diagram of one way the Higgs boson may be produced at the LHC. Here, two quarks each emit a W or Z boson, which combine to make a neutral Higgs.
A Feynman diagram of one way the Higgs boson may be produced at the LHC. Here, two quarks each emit a W or Z boson, which combine to make a neutral Higgs.
A simulated event in the CMS detector, featuring the appearance of the Higgs boson.
A simulated event in the CMS detector, featuring the appearance of the Higgs boson.
When in operation, about seven thousand scientists from eighty countries will have access to the LHC. It is theorized that the collider will produce the elusive Higgs boson, the last unobserved particle among those predicted by the Standard Model. The verification of the existence of the Higgs boson would shed light on the mechanism of electroweak symmetry breaking, through which the particles of the Standard Model are thought to acquire their mass. In addition to the Higgs boson, new particles predicted by possible extensions of the Standard Model might be produced at the LHC. More generally, physicists hope that the LHC will enhance their ability to answer the following questions:
* Is the Higgs mechanism for generating elementary particle masses in the Standard Model indeed realised in nature?
* Are electromagnetism, the strong nuclear force and the weak nuclear force just different manifestations of a single unified force, as predicted by various Grand Unification Theories?
* Why is gravity so many orders of magnitude weaker than the other three fundamental forces? See also Hierarchy problem.
* Is Supersymmetry realised in nature, implying that the known Standard Model particles have supersymmetric partners?
* Will the more precise measurements of the masses and decays of the quarks continue to be mutually consistent within the Standard Model?
* Why are there apparent violations of the symmetry between matter and antimatter? See also CP-violation.
* What is the nature of dark matter and dark energy?
* Are there extra dimensions
Of the possible discoveries the LHC might make, only the discovery of the Higgs particle is relatively uncontroversial, but even this is not considered a certainty. Stephen Hawking said in a BBC interview that "I think it will be much more exciting if we don't find the Higgs. That will show something is wrong, and we need to think again. I have a bet of one hundred dollars that we won't find the Higgs." In the same interview Hawking mentions the possibility of finding superpartners and adds that "whatever the LHC finds, or fails to find, the results will tell us a lot about the structure of the universe."
As an ion collider
The LHC physics programme is mainly based on proton–proton collisions. However, shorter running periods, typically one month per year, with heavy-ion collisions are included in the programme. While lighter ions are considered as well, the baseline scheme deals with lead ions.
Test timeline
The first beam was circulated through the collider on the morning of 10 September 2008.
The first high-energy collisions are expected to take place 6-8 weeks after the start of LHC commissioning on September 10. In the 2008 run, however, the LHC will operate at a reduced energy of 10 TeV. The winter shut-down (starting likely around end of November) will then be used to train
Expected results
Once the supercollider is up and running, CERN scientists estimate that if the Standard Model is correct, a Higgs boson may be produced every few hours. At this rate, it may take up to three years to collect enough statistics unambiguously to discover the Higgs boson. Similarly, it may take one year or more before sufficient results concerning supersymmetric particles have been gathered to draw meaningful conclusions.
Proposed upgrade
CMS detector for LHC
CMS detector for LHC
Main article: Super Large Hadron Collider
After some years of running, any particle physics experiment typically begins to suffer from diminishing returns; each additional year of operation discovers less than the year before. The way around the diminishing returns is to upgrade the experiment, either in energy or in luminosity. A luminosity upgrade of the LHC, called the Super LHC, has been proposed,
Cost
The total cost of the project is expected to be €3.2–6.4 billion.
David King, the former Chief Scientific Officer for the United Kingdom, has criticised the LHC for taking a higher priority for funds than solving the Earth's major challenges; principally climate change, but also population growth and poverty in Africa.
Computing resources
The LHC Computing Grid is being constructed to handle the massive amounts of data produced by the Large Hadron Collider. It incorporates both private fiber optic cable links and existing high-speed portions of the public Internet, enabling data transfer from CERN to academic institutions around the world.
The distributed computing project LHC@home was started to support the construction and calibration of the LHC. The project uses the BOINC platform to simulate how particles will travel in the tunnel. With this information, the scientists will be able to determine how the magnets should be calibrated to gain the most stable "orbit" of the beams in the ring.
On 10 September 2008, a group identifying as the Greek Security Team managed to hack a computer system of the Large Hadron Collider charged to analyze the data from the Compact Muon Solenoid detector.
Safety issues
Safety of particle collisions
Main article: Safety of the Large Hadron Collider
Although there have been questions concerning the safety of the planned experiments in the media and even through the courts, the consensus in the scientific community is that there is no basis for any conceivable threat from the LHC particle collisions.
Operational safety
The size of the LHC constitutes an exceptional engineering challenge with unique operational issues on account of the huge energy stored in the magnets and the beams.
Loss of only one ten-millionth part (10−7) of the beam is sufficient to quench a superconducting magnet, while the beam dump must absorb an energy equivalent to that of a typical air-dropped bomb. These immense energies are even more impressive considering how little matter is carrying it: under nominal operating conditions (2,808 bunches per beam, 1.15×1011 protons per bunch), the beam pipes contain 1.0×10-9 gram of hydrogen, which, in standard conditions for temperature and pressure, would fill the volume of one grain of fine sand.
Construction accidents and delays
On 25 October 2005, a technician was killed in the LHC tunnel when a crane load was accidentally dropped.
In popular culture
Aerial view of CERN and the surrounding region of Switzerland and France
Aerial view of CERN and the surrounding region of Switzerland and France
The Large Hadron Collider was featured in Angels & Demons by Dan Brown, which involves dangerous antimatter created at the LHC used as a weapon against the Vatican. CERN published a "Fact or Fiction?" page discussing the accuracy of the book's portrayal of the LHC, CERN, and particle physics in general.
CERN employee Katherine McAlpine's "Large Hadron Rap"
BBC Radio 4 commemorated the switch-on of the LHC on 10 September 2008 with "Big Bang Day".
That Large Hadron Collider is going to kill us all
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4.
It's a series of tubes.
They're firing up the Large Hadron Collider today! Gonna smash some particles!
Oh shi-
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5.
Worlds largest particle accelerator built on the border of Switzerland and France 150 meters (164 yards for Americans) under ground so that the scientist using it would forget the fact that they don't have a girlfriend.
It has the potential to destroy all life on Earth, but the scientist assure us that everything will be ok.
If you're reading this, it means that the experiment went ok (by the time this is published September 10, 2008 will pass).
case of a bad scenario:
scientist 1: I don't have a girlfriend.
scientist 2: Neither do I!
scientist 1: Hey! We should apply scorched Earth strategy. If we can't have fun, nobody will. Let's blow up the world with our Large Hadron Collider.
case of a good scenario:
scientist: We just fired up the LHC and it was great! I don't know what the fuck happened but it was great!
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