Last year Cosmos magazine featured the IceCube Neutrino Observatory a US$271 million project to drill down two and a half kilometres into the Antarctic ice to create a giant neutrino detector.
IceCube has been looking for very high-energy neutrinos scientists believe, are created deep inside some of the universe’s most violent phenomena.
The particles created in these events, including neutrinos and cosmic rays, are accelerated to energy levels that exceed the record-setting earthbound accelerators such as the Large Hadron Collider by a factor of more than a million.
Now, having sorted through the billions of subatomic particles that zip through its frozen cubic-kilometer-sized detector each year, the IceCube scientists have published a new study highlighting the detection of 21 ultra high-energy muons – secondary particles created on the very rare occasions when neutrinos interact with other particles – that provides independent confirmation of astrophysical neutrinos from our galaxy as well as cosmic neutrinos from sources outside the Milky Way.
The observations are reported in a paper published in the journal Physical Review Letters by the IceCube Collaboration.
That paper called the data an “unequivocal signal” for astrophysical neutrinos – ultra high-energy particles that have crossed space.
“Looking for muon neutrinos reaching the detector through the Earth is the way IceCube was supposed to do neutrino astronomy and it has delivered,” explains Francis Halzen, a UW-Madison professor of physics and the principal investigator of IceCube. “This is as close to independent confirmation as one can get with a unique instrument.”
Between May 2010 and May 2012, IceCube recorded more than 35,000 neutrinos. However, only about two dozen of those neutrino events were clocked at energy levels indicative of astrophysical or cosmic sources.
Bill Condie is a science journalist based in Adelaide, Australia.
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