The zeus uranium calorimeter - 15 Years of successful operation

One of the main components of the ZEUS detector at the HERA storage ring is the Uranium Calorimeter (UCAL). It has been running successfully from 1992 when ZEUS started data taking until summer 2007. The UCAL is a uranium-scintillator calorimeter with equal response for electrons and hadrons (e/h = 1.00 plusmn 0.05), a linear energy response and a high energy resolution of sigma(E)/E = 18%/radic(E) for electrons and sigma(E)/E = 35%/radic(E) for hadrons. It covers 99.7% of the solid angle and is able to handle bunch crossing rate of up to 10.4 MHz. This performance demands a very precise calibration and a constant monitoring of the detector. In this paper we present the good performance of this calorimeter over 15 years. Main hardware issues and operating experience are summarised.