Physicists are curious about the events that occur during and after a particle's collision. For this reason, they place detectors in the regions which will be showered with particles following an event. Detectors are built in different ways according to the type of collision they analyize.

Fixed Target: With a fixed-target experiment the particles produced generally fly in the forward direction, so detectors are cone shaped and are placed "downstream."

Colliding Beams: During a colliding-beam experiment, the particles radiate in all directions, so the detector is spherical or, more commonly, cylindrical.