The OPERA experiment has been designed to perform the most
straightforward test of the phenomenon of neutrino oscillations. This
experiment exploits the CNGS high-intensity and high-energy beam of
muon neutrinos produced at the CERN SPS in Geneva pointing towards the
LNGS underground laboratory at Gran Sasso, 730 km away in central
Italy. OPERA is located in the Hall C of LNGS and it is aimed at
detecting for the first time the appearance of tau-neutrinos from the
transmutation (oscillation) of muon-neutrinos during their 3
millisecond travel from Geneva to Gran Sasso. In OPERA, tau-leptons
resulting from the interaction of tau-neutrinos will be observed in
"bricks" of photographic emulsion films interleaved with lead plates.
The apparatus contains about 150000 of such bricks for a total mass of
1300 tons and is complemented by electronic detectors (trackers and
spectrometers) and ancillary infrastructure. Its construction has been
completed in spring 2008 and the experiment was taking data up to the end of 2012.
During this period, about 18 *10**19 of protons on target were delivered by the CERN SPS accelerator, and 16879 of neutrino events were registered in the fiducial volume of the detector. The data analysis is ongoing, so far 5 tau neutrino candidate events were found. Given the extremely small background of only 0.23 events expected from all the sources, the current results confirm with a significance of 5.1 sigma the hypothesis of the muon neutrino oscillations to tau neutrinos as a dominant process responsible for the deficit of atmospheric muon neutrinos and the results of the disappearance accelerator neutrino experiments (K2K, MINOS).
See "News and Updates" for the OPERA neutrino tau analysis
See also (830) 914-9270