Neutrino oscillation Observed First confirmation that particle changes between muon-type to tau-type.
Researchers on the OPERA experiment at the INFN1′s Gran Sasso laboratory in Italy today announced the first direct observation of a tau particle that changed from a muon neutrino beam sent from CERN directly through the Earth (730km away).
This results solves a problem that has been pending since the 1960.
Ray Davis, who won the Nobel Prize identified the problem. He noticed there were not enough neuturinos arriving from the Sun. So either the models were wrong or something was happening to the neutrinos
In 1969, Bruno Pontecorvo and Vladimir Gribov suggested the neutrinos might flip between muon-type and tau-type neutrinos.
Several experiments since have observed the disappearance of muon-neutrinos, confirming the oscillation hypothesis, but until now no observations of the appearance of a tau-neutrino in a pure muon-neutrino beam have been observed: this is the first time that the neutrino chameleon has been caught in the act of changing from muon-type to tau-type.