Performance of the DELPHI small angle tile calorimeter

The DELPHI STIC detector is a lead-scintillator sampling calorimeter with wavelength shifting optical fibers used for light collection. The main goal of the calorimeter at LEP100 is to measure the luminosity with an accuracy better than 0.1%. The detector has been in operation since the 1994 LEP run. Presented here is the performance measured during the 1994-1995 LEP runs, with the emphasis on the achieved energy and space resolution, the long-term stability and the efficiency of the detector. The new bunch-trains mode of LEP requires a rather sophisticated trigger and timing scheme which is also presented. To control the trigger efficiency and stability of the calorimeter channels, a LED-based monitoring system has been developed.