Use of proximity focused HPDs for the inner trigger detector of the FINUDA experiment

A barrel scintillator detector viewed by proximity focused HPDs will be employed in the inner region of the FINUDA experiment inside a 1.1 T magnetic field to provide a fast first level trigger, the common stop for drift chambers and straw tubes and the start signal for Time-of-Flight (ToF) measurements. The overall performances have been tested with a laser system and 90Sr radiation source.