The Compact Muon Solenoid (CMS) Hadron Calorimeter

The Hadron Calorimeter of the CMS detector for the CERN LHC accelerator is designed to measure hadron jets as well as single hadrons. It has four segments. The central barrel made of brass and scintillators that cover the |eta| range of about 0 to 1.3. The End Caps, also made of brass and scintillators extends the eta range to 3.0. The Forward calorimeter made of iron and quartz fibers cover the range 3.0 to 5.0. Since the barrel portion of the calorimeter is only 6.5 interaction lengths, the outer barrel will sample, by scintillators, outside the magnet coil and cryostat. Progress has been made on all subsystems and prototypes have been built. We now have a better understanding of magnetic field effects on calorimeters.