The Oscillation Project with Emulsion-tRacking Apparatus (OPERA) was an instrument used in a scientific experiment for detecting tau neutrinos from muon neutrino oscillations. The experiment is a collaboration between CERN in Geneva, Switzerland, and the Laboratori Nazionali del Gran Sasso (LNGS) in Gran Sasso, Italy and uses the CERN Neutrinos to Gran Sasso (CNGS) neutrino beam.
The process started with protons from the Super Proton Synchrotron (SPS) at CERN being fired in pulses at a carbon target to produce pions and kaons. These particles decay to produce muons and neutrinos.[1]
The beam from CERN was stopped on 3 December 2012,[2] ending data taking, but the analysis of the collected data has continued.
3 December 2012 After 5 years of operation the CNGS beam was stopped. In total it was 17.97×1019 protons on target provided by the CNGS.