Finding Neutrinos in a Cubic Kilometer of Ice
Spectrum's Glenn Zorpette reports from Antarctica
This is part of the series:
Antarctica: Life on the Ice
Transcript: Finding Neutrinos in a Cubic Kilometer of Ice
Glenn Zorpette: Neutrinos are among the most common things in the universe—and yet they’re also among the most difficult to detect. In a unique effort to see these subatomic particles, engineers are now turning a cubic kilometer of ice under the South Pole into one of the oddest telescopes in the world. By spotting some of the countless neutrinos that streak across the universe, this telescope should help scientists understand mysterious things: like black holes, exploding stars, and dark matter, the invisible stuff that makes up 23 percent of our universe.
Glenn Zorpette: How do you make a hole two and a half kilometers down into solid ice? You melt your way down. It takes two days and 20 000 gallons of hot water. Dennis Dillings showed me how it’s done.
Dennis Dillings: That’s our drill water for this project.
Glenn Zorpette: So you actually use hot water to drill?
Dennis Dillings: Yes we do.
Glenn Zorpette: There’s no metal bit. Just hot water.
Dennis Dillings: We use 200 gallons a minute at 90 ¿C which is boiling in the environment. And we push it out at 1000 pounds of pressure out of a three-quarter-inch nozzle. That equates up to the power of a Burlington locomotive, a big one at full power, coming out of that nozzle. That’s why this drill will drill what it drills.
Glenn Zorpette: Dillings is the drill manager for the company building the IceCube observatory. So far he’s drilled 79 of these mile-and-a-half holes in a kilometer-square stretch of ice near the South Pole. He has seven more to go.
Glenn Zorpette: Once a hole is drilled, technicians lower into it a string of 60 basketball-sized light detectors. By February of 2011, over 5000 detectors will lie frozen in a billion tons of ice. They’re going to look for the most elusive particles in the universe: neutrinos.
Mark Krasberg: Neutrinos are really neat—they’re chargeless, they’re almost massless. You’ve actually got 10 million going through your thumb every second. They’re really, really hard to detect.
Glenn Zorpette: Mark Krasberg is a physicist on the IceCube project. He explains that because neutrinos don’t interact with anything, they’re very hard to detect. But that same lack of interaction also means they can zip across vast stretches of the universe unimpeded. So to astronomers, neutrinos are like minuscule messengers carrying news about exploding stars, baby black holes, and other violent events that occurred unimaginably far away, and an unimaginably long time ago.
Mark Krasberg: …since neutrinos are chargeless, they go on a straight line through the universe. You basically, if you have a source, just have a straight line going back, and you can ask an astronomer, What’s at that spot in the sky?
Glenn Zorpette: Neutrinos can also come from sources closer to home. In fact, neutrinos coming from the center of our Sun or our Milky Way galaxy could give physicists clues about the nature of dark matter, the mystery mass that pervades our universe but about which nothing is known. But how do you detect particles that are almost undetectable? Well, the IceCube telescope is looking for the one-in-a-million neutrino that crashes into an atom of an ice molecule and creates another particle called a muon. As that muon shoots through the ice, it gives off blue light. In the pure, incredibly clear ice of the South Pole, that tiny bit of light can travel hundreds of feet. And then it can hit those basketball-size light detectors.
Mark Krasberg: It’s basically an inverse lightbulb. It collects the light and converts it into charge. There’s a computer on top of here and the signals go to the surface.
Glenn Zorpette: Researchers hope these ghostly particles will help them solve some of the biggest mysteries of the universe. If they do, then one day this strange telescope under the ice might not seem so strange after all.