The description of the detector.
Particle detectors are high-tech devices used to study the interactions of composite and elementary particles. The detected particles can originate from nuclear decays, cosmic radiation or interactions in a particle accelerator. Modern detectors, such as those used at the LHC consist of many components, of which many are specialized to detect certain particles or certain particle properties.
The tracker helps us to calculate the momentum of charged particles. They bend due to magnetic field. The smaller the curve radius is, the less momentum the particle had. We also differentiate positive and negative particles based on the direction of the track.
The Electromagnetic Calorimeter (ECAL) is used to measure the energies of electrons and photons.
The Hadron Calorimeter (HCAL) is used to measure the energy of hadrons, particles made of quarks and gluons. Some examples of them are protons, neutrons and pions. It also helps us detect neutrinos but indirectly. Energy needs to be conserved, so if we observe missing enery, this indicates neutrinos.
Muons are charged particles that are just like electrons and positrons, but are 200 times more massive. Because they can penetrate several metres of iron without interacting, the muon chamber is placed at the very edge of the detector where they are the only particles likely to register a signal.