ATLAS is a particle physics experiment at the Large Hadron Collider at CERN that is searching for new discoveries in the head-on collisions of protons of extraordinarily high energy. ATLAS will learn about the basic forces that have shaped our Universe since the beginning of time and that will determine its fate.
This video shows an animation of an actual ATLAS proton collision event. The two muons are detailed as long blue tracks, the two electrons as short blue tracks matching green clusters of energy in the calorimeters which lie outside the inner tracking detector. This event may show a Higgs boson decaying into two muons and two electrons.