Modern particle detectors consist of a large number of different subdetectors of different types, each type having a well-defined task in the detection procedure. The scientists can deduce what happens during a particle collision by combining information from the different subdetectors.

Primarily three kinds of subdetectors are used at particle physics experiments:

• Closest to the collision point are track detectors that show the trajectories and scattering angles of charged particles.
• Outside the track detectors are calorimeters that measure the energy of both charged and neutral particles.
• Furthest from the collision point are muon detectors that identify muons.

The calorimeters are further divided into electromagnetic and hadronic calorimeters, with the electromagnetic ones closest to the collision point.

Click on the link below to start an animation that shows how different particles are seen when they travel in a typical detector. The animation shows a slice through the CMS detector, which is one of the two big detectors in the coming LHC accelerator. In the animation you can click on the four types of particles in the upper left corner to see what happens when particles of such types are detected. The animation needs the program Macromedia Flash Player.

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