MELISSA BLOCK, host: From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.
MICHELE NORRIS, host: And I'm Michele Norris.
Physicists who study the building blocks of the universe have just said goodbye to a beloved giant in their field, not a fellow scientist but a machine. It's a huge device near Chicago called the Tevatron.
For a quarter century, it was the most powerful machine of its kind in the world and today scientists shut it down. NPR's Nell Greenfieldboyce has this remembrance.
NELL GREENFIELDBOYCE: The Tevatron was designed to reveal the mysterious innards of tiny atoms. To do that, the machine had to be really complicated and really big. It sent bits of atoms racing through an underground tunnel four miles around. Protons and antiprotons sped up to nearly the speed of light, then smashed together.
Scientists sifted through the subatomic rubble for clues about hidden particles.
ROGER DIXON: It was a very interesting machine to work on in the first place because we knew we were building something that had never been built before.
GREENFIELDBOYCE: I met Roger Dixon last month at the Fermi National Accelerator Laboratory in Illinois. We stood in the Tevatron's main control room surrounded by glowing computer screens.
How long have you worked here?
DIXON: Thirty-four years. Do I have to admit that on the radio?
GREENFIELDBOYCE: Dixon says the Tevatron didn't always cooperate.
DIXON: It definitely has a personality and that started right away. It had an attitude at the beginning.
GREENFIELDBOYCE: It did not forgive mistakes. As one operator wrote, the Tevatron taught me humility and gave me paranoia.
But Dixon says caretakers battled floods, blizzards, weird equipment failures to keep it running 24 hours a day because it was worth it.
DIXON: This machine has certainly opened windows on the universe that you couldn't imagine opening before, so it's done a great job.
GREENFIELDBOYCE: For example, the Tevatron is where the top quark was discovered, confirming scientists' predictions about the fundamental nature of matter. And the technology inside this machine laid the foundation for an even bigger and more powerful particle collider that's just fired up in Europe. That collider is what finally made the Tevatron obsolete.
So today, a physicist named Helen Edwards stood in the Tevatron's control room. Decades ago, she led the construction of this machine. She got the honor of shutting it down.
When operations expert, Bob Mau told her to, she pushed a big, red button. He pointed to a computer screen.
BOB MAU: As you can see on the red display, the line has gone to zero, so there is no longer any colliding beams or protons and antiprotons in the Tevatron.
GREENFIELDBOYCE: Then he told her to push a blue button to turn off power to its four mile ring of super-conducting magnets. For a long moment, nothing happened on the computer screen. Then, a green line began to drop.
MAU: There it goes. It didn't want to give up so easy.
GREENFIELDBOYCE: The power faded away and that was that. Everyone then went to a party, a kind of wake for the Tevatron. Its scientists will now turn to other experiments and the lab hopes to build new physics machines to probe elusive particles like neutrinos.
The silent Tevatron will eventually be opened up for public tours to let people see the machine that was once the greatest in the world.
Nell Greenfieldboyce, NPR News.