Performances of the AMS-02 Electromagnetic Calorimeter

A full-scale prototype of the e.m. calorimeter for the AMS-02 experiment was tested at Cern in October 2001 using 100 GeV pions and electrons beams with energy ranging from 3 to 100 GeV. The detector, a lead-scintillating fibers sampling calorimeter about 17 radiation lengths deep, is read out by an array of multi-anode photomultipliers. The calorimeter's high granularity allows to image the longitudinal and lateral showers development, a key issue to provide high electron/hadron discrimination. From the test beam data, linearity and energy resolution were measured as well as the effective sampling thickness. The latter was extracted from the data by fitting the longitudinal e.m. showers profiles at different energies.