Outside the tracking detectors are calorimeters that detect the energy of particles. The energy of both neutral and charged particles can be measured using calorimeters.
When a particle enters a calorimeter it collides with the dense material in the detector. The collisions give rise to a shower of secondary particles and the energy of the original particle is absorbed in the calorimeter. Because of this are calorimeters located outside the track detectors so that the trajectory of the particle already have been registered before it is absorbed in the calorimeter.
Normally muons and neutrinos are the only particles that pass through the calorimeters and continue to the muon detectors.