Measurement of the Pion Energy Response and Resolution in the CMS HCAL Test Beam 2002 Experiment

The Hadron Calorimeter Test Beam 2002 Experiment studied the performance of the CMS calorimeters in measuring single electrons, pions, and muons. This note addresses the particular case of the HCAL (barrel) properties to measure hadrons, such as the detector energy resolution and response linearity as a function of the pion beam energy. The detector configuration included a mock-up of the electromagnetic calorimeter (ECAL), and two hadronic barrel modules (HB). In the 20-300 GeV energy range tested, the pion energy resolution and response linearity were consistent with design values. The energy distributions show non-Gaussian tails due to the non-compensating nature of the CMS calorimeters, as well as energy leakage beyond the ECAL-HB outer boundary. Below 30 GeV, the systematic uncertainties are too large for the measurements to be relevant.