Observation of a first ντ candidate event in the OPERA experiment in the CNGS beam

The OPERA experiment is aimed to prove the existence of νμ→ντ oscillation through the observation of the tau decay topology in ντ CC interactions. The physics run started in 2008 and, since then, the lead-emulsion target has been exposed to the CNGS neutrino beam every year, from spring to autum. Untill now, 1921 neutrino interaction vertices have been located and the decay search analysis has been completed for 1088 of them. One tau neutrino candidate has been found. Here, the event location and decay search procedures will be described and the tau neutrino candidate is presented.