• inner detector (yellow) - measures the momentum of each charged particle
• calorimeter (orange and green) - measures the energies carried by the particles
• muon spectrometer (blue) - Identifies and measures the momenta of muons
• magnet system (grey) - bending charged particles for momentum measurement

The interactions in the ATLAS detectors will create an enormous dataflow. To digest this data we need:

• the trigger system - selecting 100 interesting events per second out of 1000 million others
• the data acquisition system - channeling the data from the detectors to the storage
• the computing system - analysing 1000 Million events recorded per year