  A forward electromagnetic calorimeter (FoCal) based on SiW technology is
being considered as a possible upgrade to the ALICE detector. This device
should in particular feature an extremely high granularity allowing gamma/pi0
discrimination out to very high momenta. The main option considered for the
high granularity layers is the use of CMOS pixel sensors. We will discuss the
motivation and design principles of the proposed calorimeter and will then
focus on the experience gained with a full CMOS-pixel calorimeter prototype.
Preliminary results of this device show very good capabilities for shower
profile measurements, and reasonable results for linearity and resolution,
which are limited by the currently incomplete calibration.
