OPERA tau neutrino candidate event 12254000036

No muon was identified by the reconstruction of the data provided by electronic detectors. The interaction was fully reconstructed in the brick, looking for tracks within an angular acceptance defined by $\tan \vartheta = 3$.</p><p>The analysis of the interface emulsion films revealed a converging path of 10 tracks, so the corresponding brick was extracted and developed.

By following back these tracks with the scan-back method, the neutrino interaction was located in the lead plate between the 39$^{th}$ and 40$^{th}$ emulsion films. The primary vertex is defined by four tracks, one of which shows a kink topology. In addition, two electromagnetic showers originated by the conversion of ${\gamma}$-rays were detected, both pointing to the primary vertex.</p><p>The $\tau$ candidate decays after a flight length of ${(1090 \pm 30)}$~${\mu}$m with a ${\theta_{kink}}$ of ${(137 \pm 4)}$~mrad.