IceCube reveals two neutrinos over 1 PeV

 

IceCube reveals two neutrinos over 1 PeV.

– extracts from the article –

In a paper submitted to Physical Review Letters, the IceCube Collaboration confirms that those two events are the two highest energy neutrinos ever observed. The events have estimated energies of 1.04 ± 0.16 and 1.14 ± 0.17 PeV, hundreds of times larger than the energy of a proton at the LHC.

Most of the neutrinos reaching the Earth originate either in the Sun or in our atmosphere through the interaction of incoming cosmic rays. However, if we look at neutrino energy, once we reach the PeV scale (the energy equivalent to 1,000,000 times the mass of a proton), neutrinos coming from far off in our galaxy or from more distant places in the visible Universe become dominant.

IceCube researchers have estimated that the probability that these two events are not background, i.e., anything else in the detector besides astrophysical neutrinos, is at the 2.8 sigma level.

OPERA observed a third neutrino tau

27 March 2013 – INFN – OPERA observed a third neutrino tau.

The OPERA international experiment at the INFN Gran Sasso Laboratory (Italy) has observed a third neutrino tau candidate from “flavour” oscillation. The “muon-type” neutrino produced at CERN in Geneva arrived at the Gran Sasso laboratory as a “tau” neutrino. An extremely rare event observed only twice before, in 2010 and in 2012.

The data analysis will be pursued for two more years searching for other tau neutrinos that could definitely prove this very rare phenomenon.