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 six segme nts. The central barrel made of brass and scintillators covers the I \h\ ra nge of about 0 to 1.3. Two End Caps, also made of brass and scintillators e xtends the \h\ range to 3.0. Two Forward calorimeters made of iron and quar tz fibers cover the range 3.0 to 5.0. Since the barrel portion of the calor imeter is only 6.5 interaction lengths, the outer barrel will sample, by sc intillators, outside the magnet coil and cryostat. Progress has been made o n all subsystems and prototypes have been built. We now have a better under standing of magnetic field effects on calorimeters.