In this Tuesday, Sept. 20, 2011 photo, physicist Dmitri Denisov, who works on one of two huge particle detectors at the Fermi National Accelerator Laboratory in Batavia, Ill., that gather data from the lab's Tevatron collider, looks over the area that houses the lab's four mile underground track. Inside the track, beams of protons and anti-protons race around at nearly the speed of light before smashing them to dislodge hidden particles that make up matter. On Friday, Sept. 30, physicists will shut down the Tevatron, a once-unrivaled atom smasher that has been eclipsed by the Large Hadron Collider buried beneath the border of France and Switzerland. (AP Photo/M. Spencer Green)