The research group of Nagoya University announced the final result of the neutrino oscillation search, assuming that 10 tau neutrinos generated as a result of the neutrino oscillation were finally observed in the Japan-Europe international joint research, long baseline neutrino oscillation experiment OPERA.
The OPERA experiment is an experiment aimed at showing that muon neutrinos oscillate into tau neutrinos.Muon neutrino beams generated using the accelerator of the European Organization for Nuclear Research (CERN) in Switzerland will be directed to the OPERA experimental device installed at the Gran Sasso underground laboratory in Italy, 730 km away, in the five years from 2008. It was irradiated over.
In nature, the existence of three types of electron, mu, and tau neutrinos is known.The university's research group has predicted a phenomenon in which one type of neutrino propagates over a long distance and then changes to another type of neutrino (“neutrino oscillation”), and by 3, this definitive OPERA experiment Five cases of evidence (a phenomenon in which muon neutrinos changed to tau neutrinos during the flight from Switzerland to Italy) were detected.This achievement also helped Professor Kajita and his colleagues win the Nobel Prize in Physics for the "Discovery of Neutrino Oscillation" in 2015.
After that, the vibration experiment OPERA, which has increased the statistics further.This time, a new analysis method aimed at improving detection efficiency was applied to all the data collected during the beam irradiation period from 2008 to 2012, and five new tau neutrino reaction candidates were detected and the analysis was completed. ..As a result, the appearance of a total of 5 tau neutrinos was captured, and the final result was announced as the neutrino oscillation was proved to be extremely reliable compared to that at the time of 10.
Paper information:[Physical Review Letters] Final Results of the OPERA Experiment on ντ Appearance in the CNGS Neutrino Beam
