Kinematical analysis with the emulsion cloud chamber in the OPERA experiment

The OPERA experiment aims at measuring for the first time neutrino oscillation in appearance mode through the detection of !! in an almost pure !μ beam produced at CERN SPS (CNGS), 730 km far from the detector. The !! appearance signal is identified through the measurement of the decay daughter particles of the " lepton produced in CC !! interactions. Since the short-lived " particle has, at the energy of the beam, an average decay length shorter than a 1 mm, a micrometric detection resolution is needed. The OPERA apparatus is hybrid, using nuclear emulsion as high precision tracker and electronic detectors for the time stamp, event localization in the target and muon reconstruction. The Emulsion Cloud Chamber technique fulfils the requirement of a microscopic resolution together with a large target mass. The kinematical analysis allowed by this technique is described.