Scientists at west suburban Fermilab will pull the plug Friday on their giant particle collider, the Tevatron.

When it began crashing particles together in 1985, the Tevatron became the world’s most powerful atom smasher. It revealed two of the 12 fundamental particles thought to make up the universe and offered clues to great mystery, such as why the universe is filled with matter instead of antimatter.

But last year Europe’s Large Hadron Collider overtook it, and the U.S. government denied a request to continue funding Fermilab’s machine for three more years.

Scientists who worked on the Tevatron say its ending is bittersweet.

“There is a certain sadness that ths wonderful story is coming to an end,” said Fermilab director Pier Oddone. “But this is really a celebration. This has been such a wonderful run. I wish the Large Hadron Collider in Europe to have as rich a life as the Tevatron has had here.”

Fermilab will still be crunching data from the Tevatron for at least another two years. Later, officials hope to build a new machine that would produce record numbers of particles, though at lower energies. Fermilab will also continue its programs in neutrino research and astrophysics.