Tevatron
|
|
Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory. The Tevatron accelerates particles in a 6.3 km ring to energies of up to 1 TeV. The Tevatron was completed in 1983 at a cost of $120 million and has been regularly upgraded since then, the Main Injector was the most substantial addition built over five years from 1994 at a cost of $299 million.
The acceleration is undertaken in a number of stages. The first stage is the 750 keV Cockcroft-Walton pre-accelerator which ionizes hydrogen gas and accelerates the negative ions created using a positive voltage. The ions then pass into the 150 meter long linear accelerator (linac) which uses oscillating electrical fields to accelerate the ions to 400 MeV. The ions then pass through a carbon foil, to remove the electrons, and the charged protons then move into the Booster.
The Booster is a small circular magnetic accelerator, the protons are passed around the Booster up to 20,000 times to attain an energy of around 8 GeV. From the Booster the particles pass into the Main Injector, which was completed in 1999 to perform a number of tasks. It can accelerate protons up to 150 GeV; it can produce 120 GeV protons for antiproton creation; it can increase antiproton energy to 120 GeV and inject protons or antiprotons into the Tevatron. The antiprotons are created by the Antiproton Source, 120 GeV protons are collided with a nickel target producing a range of particles including antiprotons which can be collected and stored in the accumulator ring. The ring can then pass the antiprotons to the Main Injector.
The Tevatron can accelerate the particles from the Main Injector up to 1 TeV (actually 980 GeV), within 320 km/h of the speed of light. The protons and antiprotons are accelerated in opposite directions, crossing paths in the CDF and D0 (zero) detectors to collide at 1.96 TeV. To hold the particles on track the Tevatron uses superconducting dipole magnets cooled in liquid helium producing 4.2 teslas.
On the 27th of September 1993 the cryogenic cooling system of the Tevatron Accelerator was named an International Historic Landmark by the American Society of Mechanical Engineers. When built in 1978 the system, which provides cryogenic liquid helium to the Tevatron's superconducting magnets, was the largest low-temperature system in existence. It maintains the coils of the magnets, which bend and focus the particle beam, in a superconducting state with a power consumption of 1/3 what it would be at normal temperatures.
In 1995, both CDF and D0 experiments announced the discovery of the Top quark.