The performance of the ZEUS calorimeter

The ZEUS experiment has now completed its third year of operation at the electron-proton collider HERA. The uranium/scintillator sampling calorimeter surrounding the inner tracking detectors has proven an essential component for the online triggering algorithms, for offline event-type identification, for kinematic variable reconstruction, and for a ariety of physics analyses. This paper summarizes the experimental context, the operating characteristics, the calibration techniques, and the performance of the calorimeter during its first three years of operation. (orig.)