The first candidate event observed by the OPERA experiment. (a) and (b) show the transverse view with the right plot being a zoom of the left. (c) shows the longitudinal view. The short red track (labeled as “4 parent”) is identified as being due to the lepton and the track of what is thought to be the tau-daughter is shown in turquoise (labeled as “8 daughter”). A kink is clearly seen, particularly in the zoomed transverse view (b), and demarked by the change in color from red to turquoise along the track. A detailed description of the likely candidates for each of the numbered tracks is given in the OPERA paper [25].
