Millions of protons and antiprotons fly in opposite directions in a large circular collider, smashing into each other at high speeds. These sorts of experiments are done at the Tevatron, a high-energy-particle collider at Fermilab in Batavia, Ill., about 42 miles west of Chicago. But on Friday, this giant collider will shut down after a little more than a quarter of a century of colliding.

The Tevatron is “the world’s highest-energy proton-antiproton collider” according to the Fermilab. “It’s both an accelerator and a collider. It accelerates protons and antiprotons to very high energies, and then stores them in a ring, and they counter rotate and collide head on,” said John Hauptman, a high-energy physicist and professor in the department of physics and astronomy at Iowa State.

Protons are injected into the Tevatron from the Main Injector Ring. They begin to build up more and more speed, and at one point antiprotons are injected.

“The higher the energy of the incoming particles, the more detail we can see,” said E. Walter Anderson, a professor who works with high-energy physics in the department of physics and astronomy at Iowa State.

These particles fly in opposite directions and collide. These collisions are recorded by data collaborations on the Tevatron.

There are a couple of reasons behind the closing of the Tevatron. One reason is because of the newer European collider, the LHC, Large Hadron Collider, at CERN.

The LHC is running at a higher energy than the Tevatron is now. “If we want to study the most fundamental particles we can get our hands on, we need higher and higher energy,” Anderson said.

The LHC is also producing more data. “It’s a huge volume of data, it’s an avalanche of data. You don’t try to compete with that. There’s no sense in duplicating things you can learn. And there’s already two big experiments at the LHC. Two’s enough, you don’t need four, two’s enough,” Hauptman said.

Another reason is that it’s costly to run a particle accelerator. It would cost millions just to run the Tevatron for another year. “It’s a losing game to keep an accelerator running forever,” Hauptman said.

Fermilab and CERN are not the only ones to use accelerators either.

“Industry uses accelerators a lot,” Hauptman said.

For instance, the Iowa State University Meat Laboratory uses a linear accelerator, using an irradiation process, to decontaminate the meat that passes through, processing 500 pounds per hour, according to the Linear Accelerator Facility at Iowa State University website.

Although Fermilab’s biggest highest energy collider will be shutting down, experiments using other lower energy accelerators, and other fields will continue. The data collected from the Tevatron’s two major data collaborations, DZero and CDF, will be analyzed as well over the next few years.