Quantum fluctuation explains missing neutrinos
4 May 2015 by Evoluted New Media
After three years of data collection, scientists have discovered why only one form of neutrino can be recorded.
A research team led by the University of Copenhagen used data from the IceCube detector, located at the South Pole, and found that quantum fluctuations allow only one type of neutrino particle – a muon neutrino – to be detected.
Research leader Professor Jason Koskinen said: “In this study, we have only measured muon neutrinos and in comparison to how many muon neutrinos form in in the atmosphere and pass through the Earth, we only see a fraction at the South Pole. The explanation is that the muon neutrinos undergo quantum fluctuations that change them into tau neutrinos and we do not see those. If they had not changed, we would see them all. Our calculations show that 20 percent have undergone quantum fluctuations and changed from muon neutrinos to another type of neutrino as they pass through the Earth.”
Neutrinos are high energy – nearly massless – particles produced by radioactive decay. Scientists believe that they are among the most abundant particles in the Universe and interact extremely weakly with matter.
“In the IceCube project we have registered about 35 neutrinos, which are very likely to have come from distant regions in space. They have a very high energy and because they have not interacted during their long journey, they can carry information from the most distant parts of the Universe,” said Professor Koskinen.
To record these particles, the scientists used the IceCube particle detector located deep in the ice at the South Pole. They set up a network of detectors and awaited neutrino particles to collide with atoms in the ice – a rare event indeed due to the weakly interactive nature of neutrinos. When collisions did occur, charged particles were created emitting radiation that was then recorded by IceCube’s digital optical modules.
In the study, published in the journal Physical Review D, the researchers also investigated the physical properties of neutrinos that come from closer to home.
“In addition to the rare cosmic neutrinos, we are also studying the neutrinos created in the Earth’s atmosphere in order to unravel the physical properties of neutrinos,” said Professor Jason Koskinen.
The team will continue to study these particles and investigate their properties.
Paper: http://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.072004
