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July 21, 2011

The world's largest astronomical instrument is in high gear, trying to ferret out the sources of the most powerful cosmic rays. Known as IceCube, it consists of more than 5,000 light detectors buried more than a mile deep in the ice at the south pole. It began full-time science operations in May.

IceCube doesn't look for cosmic rays themselves. But the same events that produce cosmic rays should also produce neutrinos -- particles that stream through space unimpeded by just about anything -- even solid planets. A scant few of them should hit molecules of Antarctic ice, though, producing flashes of light that IceCube will detect.

Frances Halzen is IceCube's leader.

HALZEN: The most publicized goal of this detector is to find the sources of the cosmic rays by hopefully detecting neutrinos that travel in a straight line from the source to our detector, unlike the cosmic rays themselves, which are charged and get scrambled in the galactic magnetic fields, and therefore don't reveal where they come from.

Some neutrinos probably come from the remains of exploded stars, known as supernova remnants, inside the Milky Way galaxy, while others probably come from powerful explosions far beyond the Milky Way.

HALZEN: If IceCube doesn't see these sources within five years then there's something wrong and we'll rule them out. Especially for supernova remnants, this would be a very interesting result, because nobody has a clue what else would do it.


Script by Damond Benningfield, Copyright 2011


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