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Typical detector components

The reason that detectors are divided into many components is that each component tests for a special set of particle properties. These components are stacked so that all particles will go through the different layers sequentially. A particle will not be evident until it either interacts with the detector in a measurable fashion, or decays into detectable particles.

The interaction of various particles with the different components of a detector:

*Neutrinos are not shown on this chart because they rarely interact with matter, and can only be detected by missing matter and energy. Just so you know, the pion () is a charged meson.*

A few important things to note:

  • Charged particles, like electrons and protons, are detected both in the tracking chamber and the electromagnetic calorimeter.
  • Neutral particles, like neutrons and photons, are not detectable in the tracking chamber; they are only evident when they interact with the detector. Photons are detected by the electromagnetic calorimeter, while neutrons are evidenced by the energy they deposit in the hadron calorimeter.
  • Each particle type has its own "signature" in the detector. For example, if a physicist detects a particle only in the electromagnetic calorimeter, then he is fairly certain that he observed a photon.

An electron and a positron were produced when a particle and its antiparticle collided head-on, perpendicular to this screen. What conservation law APPEARS to have been broken?

Number of Leptons?