The Tevatron was a circular particle accelerator at the Fermi National Accelerator Laboratory (also known as Fermilab), just east of Batavia, Illinois. It was the second highest energy particle collider in the world after the Large Hadron Collider (LHC). The Tevatron is a synchrotron that accelerates protons and antiprotons in a 6.28 km (3.90 miles) ring to energies of up to 1 TeV, hence its name. The Tevatron was completed in 1983 at a cost of $120 million ($ today) and has been regularly upgraded since then. (The 'Energy Doubler', as it was known then, produced its first accelerated beam — 512 GeV — on July 3, 1983.) The "Main Injector" was the most substantial addition, built over five years from 1994 at a cost of $290 million. The Tevatron was shut down on September 30, 2011.