  A prototype silicon-tungsten electromagnetic calorimeter for an ILC detector
was tested in 2007 at the CERN SPS test beam. Data were collected with electron
and hadron beams in the energy range 8 to 80 GeV. The analysis described here
focuses on the interactions of pions in the calorimeter. One of the main
objectives of the CALICE program is to validate the Monte Carlo tools available
for the design of a full-sized detector. The interactions of pions in the Si-W
calorimeter are therefore confronted with the predictions of various physical
models implemented in the GEANT4 simulation framework.
