THE PERFORMANCE OF THE CMS HADRON CALORIMETER WITH COSMIC MUONS

The hadron calorimeter (HCAL) is now installed in the CMS detector and ready to take collision data. The CMS HCAL barrel and end caps are made of scintillator and brass absorber covering the vertical bar eta vertical bar range of 0.0 to 3.0. The forward calorimeter, made of quartz fibers and iron absorber, covers the vertical bar eta vertical bar range of 3.0 to 5.0. These systems are now installed and integrated in the detector and participated in data taking with over 600 million cosmic muons taken with and without the CMS magnet on. In addition, CMS took data during four days in September 2008, when LHC provided a single proton beam at 450 GeV/c impinging on a collimator near CMS. The HCAL is ready to take collider data and performs as designed.