Arctic observatory finds 'alien' particles

Possible signals from at least 26 suspected high-energy neutrinos of as yet unknown origin have been picked up by a particle detector at the IceCube Neutrino Observatory near the South Pole, a science site has reported.

 

Scientists said the preliminary data showed the newly-found neutrinos are less energetic than two record-setters earlier discovered, ScientificAmerican.com reported.

 

“The result right now is very preliminary ... We’re not totally certain right now that it’s from an astrophysical source,” it quoted Nathan Whitehorn of the University of Wisconsin–Madison, who described the new data May 15 during a symposium in Madison on particle astrophysics, as saying.

 

Yet, the site said the possible neutrions appear to carry more energy than if caused by cosmic rays hitting the atmosphere.

 

For now, Whitehorn said it is difficult to explain the number and energy of the detected particles using known processes in the solar system.

 

“If this does in fact hold up with more data, and this does turn out to be an astrophysical source, then we’ll be able to address some questions in ways that were totally inaccessible before,” he said.

 

Physicists at IceCube are trying to work out the origins of high-energy cosmic rays, or charged particles from space that hit Earth. This may bear on the origins of neutrinos as well.

 

Wide net

 

Since neutrinos, lightweight fundamental particles, rarely interact with atoms of matter, the IceCube Neutrino Observatory is casting a wide net of more than 5,000 light sensors, buried at depths of up to 2 km embedded in Antarctic ice.

 

Researchers hope to have at least one neutrino by chance bump against an atom in the ice, and produce a tiny flash of light.

 

Light from such a neutrino strike is recorded in the IceCube detector.

 

On the other hand, researchers used screening techniques to filter out impostor particles and limit background noise from atmospheric neutrinos.

 

“You don’t want things that have come into the detector, you want things that start in the detector,” said IceCube physicist Claudio Kopper of U.W.–Madison.

 

ScientificAmerican.com said researchers expected to register about 10.6 particles over two years, with energies in the tens or hundreds of tera–electron volts or trillions of electron volts.

 

So far, it said the 28 detected particles, including two extremely high-energy particles announced in April, indicate an additional neutrino source that has not been accounted for.

 

IceCube physicist Naoko Kurahashi Neilson, also of U.W.–Madison, traced the directions of the newfound energetic particles to look for clues to their origins.

 

“What I tried to do is figure out if they point back to anything that might correspond with cosmic-ray production,” she said.

 

However, no strong patterns emerged as there were relatively few particles to work with, prompting her to conclude that "there are no identifiable sources at this time.”

 

Screening techniques

 

For now, the scientists said proving the neutrinos originated in high-energy cosmic processes will take time.

 

“The search is always for the source, and we haven’t found that yet. That would be the smoking gun,” Kopper said. — TJD, GMA News