The 4-mile-in-circumference Tevatron accelerator, shut down in September 2011, is one of eight particle accelerators and storage rings at the Department of Energy’s Fermilab. It used superconducting magnets to propel protons and antiprotons to nearly the speed of light. In the foreground is the 2-mile Main Injector accelerator, which powers Fermilab’s neutrino and muon research programs.