Prototype of a new lead-scintillating tile calorimeter: design and test beam results

Summary form only. The DELPHI collaboration has decided to replace the existing Small Angle Tagger by a new calorimeter with better performance. A prototype comprising three azimuthal sectors and four radial layers of towers has been built and exposed to electrons of energy up to 70 GeV on the CERN SPS West Area test beam. The technical choices on how to read out the Sci-Tiles by means of wavelength shifter fibers distributed over the title cross section with a density of roughly 1 fiber/cm² have been considered. During the test the incoming beam particle trajectory has been defined by an array of silicon microstrip detectors which define the impact point to better than 10 μ. With this good definition of the beam it is possible to study the spatial reconstruction of the impact point with great accuracy. This parameter is extremely important as the calorimeter is aiming to measure with better than 2% precision the luminosity of DELPHI in the future high luminosity runs at LEP