Testbeam results for a Shashlik calorimeter with longitudinal segmentation

In the frame of research and development for electromagnetic calorimetry at future e/sup +/e/sup -/ linear colliders, different techniques have been studied to implement longitudinal segmentation in Shashlik calorimeters. Two prototypes with 5/spl times/5 cm/sup 2/ lead/scintillator towers and readout by means of wavelength-shifting fibers have been built. The longitudinal segmentation of the shower is achieved by modifying the front part of the detector. In the first prototype, vacuum photodiodes have been inserted laterally for the first eight X/sub 0/, while in the second prototype a slow scintillator has been used in the first five X/sub 0/. Both of the prototypes have been exposed to beam at CERN. The performance in term of energy resolution, spatial resolution, and e//spl pi/ separation are described.