Muon/antimuon events are probably the easiest to identify due to a very characteristic track those particles leave in the detector.

Just like electron/positron events these events leave in almost all cases two clearly visible tracks in the detector. Since (anti-)muons are (almost) the only charged particles, that can break through the electromagnetic calorimeter, they show very characteristic, green detector hits in the kaon-muon-calorimeter along their outer tracks.

As you can see on the example pictures down below one can see these green hits very well for both tracks and therefore sort these events very well.

Since only the muon and antimuon are produces and these don’t decay any further within the detector, these events usually have very little missing energy and high straightness.