Huge detector under Antarctic ice may have seen first cosmic neutrinos

May 15, 2013 at 6:12 PM
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MADISON, Wis., May 15 (UPI) -- A giant experiment buried beneath the South Pole's ice has recorded the first neutrinos ever detected originating outside our solar system, researchers say.

Neutrinos are produced in our atmosphere but the IceCube experiment -- a cubic kilometer of sensitive detectors sunk into the Antarctic ice -- has seen the first "cosmic neutrinos," they said.

IceCube consists of 86 strings, each with 60 sensitive light detectors strung along it like "fairy lights," sunk deep into the ice.

Rare collisions of neutrinos with the nuclei of atoms in the ice produce a brief flash that the detectors can catch.

With more than 5,000 detectors catching the flashes the direction of the neutrinos' arrival on Earth can be determined, the researchers said.

Neutrinos can be produced in the Earth's atmosphere -- IceCube picks up about 100,000 of that variety a year -- but previous attempts to isolate neutrinos created in far-flung cosmic processes had all failed.

However, in April the IceCube research team reported detecting two neutrinos -- nicknamed Bert and Ernie -- with energy levels high enough to suggest a cosmic rather than atmospheric origin.

The team has now reported 26 more events of similar energy that they expect will also be confirmed as cosmic in origin.

Detection is just a first step and "of course, there's much more to do," IceCube principle investigator Francis Halzen told BBC News.

"It's after you find them that the work starts; these events are very difficult to analyze."

The study results were presented Wednesday at the IceCube Particle Astrophysics Symposium in Madison, Wis.

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