An Appearance Experiment to Search for $\nu_\mu$ $\leftrightarrow$ $\nu_\tau$ Oscillations in the CNGS Beam

The OPERA$^4$ experiment is proposed for an appearance search of $\nu_\mu$ $\leftrightarrow$ $\nu_\tau$ oscillations in the parameter region indicated by Super-Kamiokande as the explanation of the zenith dependence of the atmospheric neutrino deficit. OPERA is a long baseline experiment to be located at the Gran Sasso Laboratory in the CNGS$^5$ neutrino beam from the CERN SPS. The detector design is based on a massive lead/nuclear emulsion target. Nuclear emulsions are use as high resolution tracking devices, for the direct observation of the decay of the $\tau$ leptons produced in $\nu_\tau$ charged current interactions. Electronic detectors locate the events in the emulsions. Magnetised iron spectrometers measure charge and momentum of muons. The discovery potential of OPERA originates from the observation of a $\nu_\tau$ signal with very low background level. The direct observation of $\nu_\mu$ $\leftrightarrow$ $\nu_\tau$ appearance will constitute a milestone in the study of neutrino oscillations. The OPERA experiment is proposed for an appearance search of $\nu_\mu$ $\leftrightarrow$ $\nu_\tau$ oscillations in the parameter region indicated by Super-Kamiokande as the explanation of the zenith dependence of the atmospheric neutrino deficit. OPERA is a long baseline experiment to be located at the Gran Sasso Laboratory in the CNGS$^5$ neutrino beam from the CERN SPS. The detector design is based on a massive lead/nuclear emulsion target. Nuclear emulsions are use as high resolution tracking devices, for the direct observation of the decay of the $\tau$ leptons produced in $\nu_\tau$ charged current interactions. Electronic detectors locate the events in the emulsions. Magnetised iron spectrometers measure charge and momentum of muons. The discovery potential of OPERA originates from the observation of a $\nu_\tau$ signal with very low background level. The direct observation of $\nu_\mu$ $\leftrightarrow$ $\nu_\tau$ appearance will constitute a milestone in the study of neutrino oscillations.