Testbeam results for a Shashlik calorimeter with longitudinal segmentation

In the frame of R & D for electromagnetic calorimetry at future e+ e- linear colliders different techniques have been studied to implement longitudinal segmentation in Shashlik calorimeters. Two prototypes with 5 multiplied by 5 cm2 lead/scintillator towers and WLS readout have been built. The longitudinal segmentation of the shower is achieved by modifying the front part of the detector. In one prototype vacuum photodiodes are inserted laterally for the first 8 radiation lengths, while in the second one fast scintillator is used in the first 5 radiation lengths. Both the prototypes have been exposed to beam at the CERN West Area, and the performance in term of energy resolution, uniformity, spatial resolution and electron/pion separation are described. The preliminary results of the exposure to the same beam of a third prototype, with a 3 multiplied by 3 cm2 lateral granularity are also presented.