Following the first evidence of neutrino oscillations provided by the Super-Kamiokande experiment in 1998, the OPERA experiment was designed to prove neutrino oscillations in the muon to tau neutrino channel through the first observation of the tau neutrino appearance in a muon neutrino beam. The detector was built from 2003 to 2007 and it took data for five years, from 2008 to 2012, with the CERN Neutrinos to Gran Sasso (CNGS), an almost pure muon neutrino beam.
We have completed the analysis of a large sample corresponding to about 90% of the data collected and we have found five tau neutrino events therein. Given the intense work aimed at the reduction of the background down to an extremely low level, this result corresponds to the discovery of the oscillation process with a five sigma level significance. The detector has shown to be unique in the capability of seeing all three active neutrinos. We report the results achieved on the oscillations and also on side analyses.
