The First WW Candidate Event Observed by L3

at 161 GeV centre-of-mass energy:
One of the two W bosons decays into two quarks, which are measured as two jets of hadrons in the detector. The other W boson decays into an electron and a neutrino. The electron deposits all its energy in the BGO electromagnetic calorimeter, causing the large cluster colored in green in the lower half of the event. The neutrino is inferred from the missing energy of the event. The picture shows a view of the event in the plane transverse to the LEP beam axis. Other views are shown here and here .