The next step is the booster ring. The booster ring is a 468 m circumference circular accelerator that uses magnets to bend beams of protons in a circular path. The protons coming from the Linac travel around the Booster about 20,000 times in 33 milliseconds so that they repeatedly experience electric fields. With each revolution the protons pick up more energy, leaving the Booster with 8 GeV. The Main Injector is the next link in the accelerator chain. Completed in 1999, it has become Fermilab's "particle switchyard" with three functions: it accelerates protons, it delivers protons for antiproton production, and it accelerates antiprotons coming from the antiproton source. The final accelerator was the Tevatron. It was the second most powerful particle accelerator in the world (CERN's Large Hadron Collider being the most powerful). Traveling at almost the speed of light, protons and antiprotons circle the Tevatron in opposite directions. Physicists coordinate the beams so that they collide at the centers of two 5,000-ton detectors DØ and CDF inside the Tevatron tunnel at energies of 1.96 TeV, revealing the conditions of matter in the early universe and its structure at the smallest scale. The Tevatron is being converted into a museum.