Scientists reported that they have found cosmic neutrinos buried deep within the Antarctic’s ice sheet. The ellusive, nearly massless subatomic particles are believed to originate from beyond our galaxy’s outer reaches and are expected to help scientists learn more about cosmic ray formation.
The discovery was made with help from the IceCube Neutrino Observatory, a scientific facility located near the South Pole. The observatory has dozens of shafts that can reach nearly 8,000 feet depths and contain detectors that scan the surrounding ice for the nearly invisible form of matter.
Neutrinos usually originate from supernovas, black holes, galactic centers, nuclear plants, and other high-radiation sources. The particles carry no electric charge and can travel through matter at breath-taking speeds as if the matter didn’t even exist. Human-made detectors cannot detect them but they do find traces left behind after neutrinos collide with matter.
Yet, because of their structure they rarely collide with other particles, but when they do, they create a new particle called muon. Antarctic scientists focused on finding those muons which are faster than the speed of light and they release faint radiation around them when interacting with other particles.
That radiation is an important hint for researchers that neutrinos are nearby. Study authors also explained that across a solid surface such as ice muons travel slower because the speed of light is constant only in empty space.
Researchers said that they had found muons generated by neutrinos coming from outside the Milky Way a couple of years ago. In the recent study, a group of scientists from the University of Wisconsin-Madison, tried to confirm the 2013 finding and make sure that the particles originated from locations outside our galaxy.
To achieve that goal, researchers analyzed neutrinos that were hitting Earth from all directions. The team explained that this type of neutrinos is not tied to our planet’s orbit and rotation, so their source cannot be located within the Milky Way.
Since 2010, the IceCube Neutrino Observatory detected over 35,000 neutrinos. About 20 particles had high enough energy to make scientists believe that they had cosmic origins. The rest were created when cosmic rays interacted with our planet’s atmosphere.
Albrecht Karle, senior researcher involved in the study said that the energy of those 20 muon neutrinos hinted that the particles had an extragalactic origin.
“This was a new discovery,”
Mr. Karle added.
A paper on the new findings was published in the journal Physical Review Letters on Thursday.
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