Events in which an electron-positron pair are produced are fairly easy to identify. We see a back-to-back pair of high momentum tracks pointing at high energy clusters of energy in the electromagnetic calorimeter.
Here are a couple of example events.
Side View of Event
Example
Event No. 2
In the second example event the electrons strike the end-cap region of the detector.
End-On View of Event
Side View of Event
Identifying Events Containing
a Particle-Antiparticle Pair.