Each photon has then produced an electron-positron pair. The direction of the magnetic field is indicated by the green axis . Note the opposite sense of curvature for the oppositely charged particles. Injected particle always moves in the plane indicated by brick-red outline. With the real program you can see the tracks traced out in slow motion , so it's obvious that a matter-antimatter pair originates from a single point.
Neutral pions are one of five types of particle that can be selected for observation in the chamber.
Others are charged pions and muons. This or any event occurring in the chamber can be seen in projection views as well. These are more like the bubble chamber photographs you may be familiar with. It is in the projection views that you can measure distances that enable you to determine particle masses . The user controls the kinetic energy of the injected particle, the chamber size, and the magnetic field strength.