The main tunnel at Fermilab, now housing both the older ring
of conventional magnets (red and blue, above) and the new
ring of superconducting magnets (yellow, below). In its present
mode of operation as the Tevatron, the superconducting ring
receives injections of protons and antiprotons from the
conventional ring. the two beams are accelerated in opposite
directions around the ring to their final energy of 1 TeV, and
then
collided together at interaction points. The Tevatron is the most
powerful accelerator in the world today. (Courtesy of Fermi Natio
al Accelerator Laboratory)