A central part of the calorimeter infrastructure is the development of a compact and dense
electromagnetic prototype, equipped with Tungsten absorbers, Si-sensors and readout chips.
Compared to existing systems the mechanics needs to be significantly improved to allow for a
denser overall design in order to provide a prototype which presents the adequate properties of
compactness and granularity. In front of possible hadronic calorimeters, this will provide
information on hadronic shower developments, longitudinal and transverse sizes, cell