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From Lightning Bolts to Synchrotrons: The Evolution of the Particle Accelerator |
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Written by Dirk Englund
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Wednesday, 04 April 2007 |
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Page 6 of 9 There are two more technological breakthroughs that allowed the even higher energies achieved by the synchrotrons of the 1980’s and 90’s. The first is the use of anti-matter. Anti-matter can be created in high-energy collisions between elementary particles (such as protons). This anti-matter can then be collided head-on with normal matter. For example, the Tevatron synchrotron at Fermi National Laboratory smashes protons into anti-protons. The two particles annihilate completely, releasing a large amount of energy (according to E = mc2). All of the kinetic energy of the particles is released as well. That extra kinetic energy can be appreciated by considering a car crash. If one car runs into another which is at rest, both will move together, leaving some of the initial energy as kinetic energy. Only a fraction of the total energy goes into bending the metal. On the other hand, if two cars crash head-on and come to rest, all of their kinetic energy goes into squashing the auto bodies. In the same way, more energy is available in the accelerator if the particles collide head-on. In 1981, the converted Super Proton Synchrotron (SPS) at CERN became the first synchrotron to smash protons into anti-protons, reaching 540 GeV (540 billion eV).2
The other major breakthrough was the application of superconductive wires for magnets. The magnets used to steer the beam are made from coils carrying a current. This current can be very large and run up a hefty electricity bill. Superconducting wires, however, have no resistance; once the current and thus the magnet is turned on, it will stay on virtually forever. One only needs to pay the electricity required to keep the wires cold and superconducting.
More importantly, superconducting magnets can produce very high magnetic fields. Currently, they can reach just under 10 Tesla—over five times higher than the best normal electromagnets and almost 100,000 times the earth’s magnetic field[8]. The superconducting technology allowed the Tevatron at Fermi National Laboratory in Illinois to reach 1 trillion eV (1 TeV) in 1985 and will be essential in future synchrotrons3 .
2This break-through in energy allowed the discovery, in 1983, of the W-and Z-bosons—the carriers of the weak nuclear force—thus confirming the theory of electro-weak interactions and unifying the weak and electromagnetic force.
3One of Tevatron’s greatest triumphs was that it proved the existence of six quarks in the standard model of particle physics.
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Last Updated ( Saturday, 29 December 2007 )
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