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Large Hadron Collider


Large Hadron Collider

Large Hadron Collider Cooldown Status

The Large Hadron Collider (LHC) is a particle accelerator built near Geneva, Switzerland. Buried approximately 50 to 175 meters underground, the Large Hadron Collider resides inside a circular tunnel roughly 27 kilometers in circumference, running along the border between Switzerland and France.

What Does the Large Hadron Collider Do?

The LHC circulates a beam of charged particles (specifically hadrons, probably either protons or lead ions) through a tube which maintains a continuous vacuum. The particles are guided through the continuous vacuum within the circular tube using a series of magnetic superconductors which accelerate and guide the charged particles. In order to maintain the superconducting properties of the magnets, they remain supercooled near absolute zero by a massive cryogenic system.

Once the beam reaches its highest energy levels, obtained by steadily increasing the energy as the beam circles repeatedly through the magnets, it will be maintained in a storage ring. This is a loop of tunnel where the magnets will keep circulating the beam so that it retains its kinetic energy, sometimes for hours on end. The beam can then be routed out of the storage ring to be sent into the various testing areas of the LHC.

The beams are expected to obtain energy levels up to 7 TeV (7 x 1012 electronvolts). Since two beams will collide with each other, the energy of the collisions are therefore anticipated to reach 14 TeV from protons.

In addition, by accelerating heavier lead ions, they anticipate collisions with energies in the range of 1,250 TeV ... energy levels on the order of those obtained only moments after the Big Bang. (Not the energies obtained during the Big Bang. The TeV energy scale is about 1016 times smaller than the Planck mass energy scale, for example, which Lee Smolin uses as the top of his particle energy scale in The Trouble with Physics. Presumably, the Big Bang energy levels would have been somewhere on this Planck energy scale or higher, where the quantum physics and general relativity aspects of reality both begin to break down.)

What Is the Large Hadron Collider Looking For?

Since the Large Hadron Collider will be having collisions of such high energy, the hope is that it will release exotic particles which are normally not observed. Any results from the Large Hadron Collider collisions should have a major impact on our understanding of physics, either confirming or refuting the projections from the Standard Model of particle physics.

One major product which is being looked for is the Higgs boson, the last particle from the Standard Model of particle physics that hasn't been observed.

It's also possible that the LHC will create some indicators of the exotic dark matter, which makes up nearly 95% of the universe but cannot be directly observed!

Similarly, there might be some evidence of the extra dimensions predicted by string theory. The fact is that we just don't know until we perform the experiments!

LHC Experiments

There are a variety of ongoing experimental systems built into CERN:

  • ATLAS (A Toroidal LHC ApparatuS) and CMS (Compact Muon Solenoid) - these two large, general purpose detectors will be capable of analyzing the particle produced in LHC collisions. Having two such detectors, designed and operated on different principles, allows independent confirmation of the results.

  • ALICE (A Large Ion Collider Experiment) - this experiment will collide lead ions, creating energies similar to those just after the Big Bang. The hope is to create the quark-gluon plasma believed to have existed at these energy levels.
  • LHCb (LHC beauty) - this detector specifically looks for the beauty quark, which will allow it to study the differences between matter and antimatter, including why our universe appears to have so much matter and so little antimatter!

  • TOTEM (TOTal Elastic and diffractive cross section Measurement) - this smaller detector will analyze "forward particles" which only brush past each other instead of having head-on collisions. It will be able to measure the size of the proton, for example, and the luminosity within the LHC.

  • LHCf (LHC forward) - this small detector also studies forward particles, but analyzes how the cascades of charged particles within the LHC relates to the cosmic rays that bombard the Earth from outer space, helping interpret and calibrate studies of the cosmic rays.

Who Runs the Large Hadron Collider?

The Large Hadron Collider was built by the European Organization for Nuclear Research (CERN). It is staffed by physicists and engineers from around the world. Nations participating in the construction and experiments consist of:
Armenia, Australia, Austria, Azerbaijan Republic, Belarus, Belgium, Brazil, Bulgaria, Canada, China, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Georgia, Germany, Greece, Hungary, India, Israel, Italy, Japan, Korea, Morocco, Netherlands, Norway, Pakistan, Poland, Portugal, Romania, Russia, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, United States, Uzbekistan

How Much Did It Cost?

The building of the accelerator, including manpower and materials, is 3.03 billion euros - roughly 4 billion U.S. dollars (using conversion from Sept. 4, 2008). On top of this, of course, is the cost of the various experiments and computing power.

How Is It Going?

The Large Hadron Collider originally went online in September of 2008 and, within about a week, had to shut down due to a leak in one of the seals that insulated the supercooled vacuum from the outside world. After about a year of repairs, the LHC went online once again, this time with much more success. In December 2009 it produced beams with an energy of 1.18 TeV each, resulting in collisions of 2.36 TeV - the most powerful experiment ever conducted on Earth. At present, physicists are still analyzing the results of these collisions to discover what the results mean.
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