The Hadronic Calorimeter (HCAL), plays an essential role in the identification and measurement of quarks, gluons, and neutrinos by measuring the energy and direction of jets and of missing transverse energy flow in events. Missing energy forms a crucial signature of new particles, like the supersymmetric partners of quarks and gluons. For good missing energy resolution, a hermetic calorimetry coverage of ||=5 is required. The HCAL also aids in the identification of electrons, photons and muons in conjunction with the tracker, electromagnetic calorimeter, and muon systems.

The barrel, or central detector, is a cylindrical structure which surrounds the collision region and measures the energy of quarks and jets emerging at large angles relative to the beam direction. The endcap calorimeters look like end-plugs and enclose the ends of the barrel region. There are two of these, one at each end of the central detector. The forward calorimeters measure energy at very small angles relative to the beam and are located outside the muon system along the beam line. There are two of these detectors, one at each end of CMS.

CMS Detector