The OPERA experiment at Gran Sasso

OPERA (Oscillation Project with Emulsion tRacking Apparatus) is a long baseline neutrino experiment aiming to detect for the first time the appearance of tau neutrinos in a pure muon neutrino beam. The OPERA detector is exposed to the CNGS beam (CERN Neutrinos to Gran Sasso), a high-intensity and high-energy beam of muon neutrinos produced at the CERN SPS and directed toward the Gran Sasso underground laboratory (LNGS), 730 km away. The LNGS laboratory is situated under an average depth of 3800 meters water equivalent, making OPERA the deepest experiment able to measure cosmic ray muons with a magnetized detector, e.g. the cosmic ray muon charge ratio. Cosmic ray events were observed, together with the first neutrino beam events, during the 2007 and 2008 CNGS runs. This paper reviews the experimental apparatus, presents the first results for neutrino data and describes the analysis of cosmic ray data.