Search for the νμ → ντ oscillation with the OPERA hybrid detector

This work reviews the status of the international OPERA experiment aimed at searching for the ν μ → ν τ oscillation. Development of the emulsion techniques in the preceding DONUT and CHORUS experiments is described. A brief overview of the NOMAD experiment is given, in which properties of ν τ interactions were thoroughly investigated. Characteristics of the CERN-Gran Sasso (CNGS) neutrino beam are given, the structure of the OPERA hybrid detector and the functions of its subsystems are considered, and the automatic emulsion scanning technique is briefly reviewed. Uncertainties in reconstruction of event parameters using the electronic and emulsion detectors are discussed and the procedure adopted in the experiment for identification of ν τ interactions is described. The main sources of background in the search for ν μ → ν τ oscillation are considered. Topologies of the first two ν τ candidates observed in the OPERA emulsion detector are presented. Possibilities of increasing the ν τ interaction selection efficiency using multidimensional criteria are briefly discussed.