The storied Tevatron particle collider, the most powerful machine of its kind in the U.S. and for many years in the world, will smash its final protons and antiprotons Friday.

The collider, which came online in 1983, accelerates particles to near light speed on a six-kilometer racetrack before steering them into head-on collisions. At those energies, the debris from collisions can contain fleeting particles never before observed by physicists. But the Tevatron has been eclipsed by Europe's larger, more powerful Large Hadron Collider, which finally powered up two years ago after a series of delays.

Tevatron physicists had lobbied for a three-year extension to the collider's operational lifetime, but the Department of Energy (DoE) turned them down in January, citing budgetary constraints.

In its 28 years of operation the Tevatron made countless contributions to particle physics. Its import is most tangibly demonstrated by the 1995 discovery of the top quark, one of the last missing pieces of the Standard Model of particle physics, the reigning framework describing the elementary particles that make up our world. The Tevatron also made significant contributions in the ongoing search for the Higgs boson, a particle hypothesized to lend mass to other particles. Tevatron experiments have not revealed the Higgs itself but have largely ruled out large swaths of theoretical terrain where it might be hiding.

The collider's home institution, DoE's Fermilab in Illinois, will mark the end of the Tevatron era September 30 with a Webcast shutdown of the particle accelerator and its two detectors, D0 and CDF, at 3:00 P.M. (Eastern Daylight Time), followed by a lab-wide party.