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Catching Neutrinos

January 28, 2015

In a cavern a half-mile below the hills of northern Minnesota, scientists and engineers have built a “battleship in a bottle” — a 6,000-ton concoction of steel and electronics designed to study some of the most ephemeral particles in the universe.

Neutrinos are produced in nuclear reactions, such as those that power the Sun and other stars. They stream through space at almost the speed of light, and zip through stars and planets without stopping. In fact, trillions of them pass through your body every second.

Early theories said that neutrinos shouldn’t have any mass. But experiments found that they come in three varieties, known as flavors. And they can change flavors as they speed along — like a scoop of ice cream morphing from chocolate to vanilla to strawberry. For this idea to be correct, neutrinos must have a small mass, with a different mass for each flavor.

The Minnesota experiment, known as MINOS, is studying how the neutrinos change as they speed through the universe. Scientists fire a beam of one flavor of neutrinos from a lab in Illinois. The beam travels hundreds of miles below Wisconsin and Lake Superior before some of its neutrinos hit the detector. There are so many neutrinos that one of them occasionally zaps an atom in the detector, causing a splash of atomic particles.

Studying these events should help scientists learn how neutrinos work — information that can help them better understand the reactions that power the stars.


Script by Damond Benningfield, Copyright 2014

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