Procedure for short-lived particle detection in the OPERA experiment and its application to charm decays

The OPERA experiment, designed to perform the first observation of \nu_\mu \rightarrow \nu_\tauoscillations in appearance mode through the detection of the \tauleptons produced in \nu_\taucharged current interactions, has collected data from 2008 to 2012. In the present paper, the procedure developed to detect \tauparticle decays, occurring over distances of the order of 1 mm from the neutrino interaction point, is described in...