HPD readout based TOF scintillator detector for the FINUDA trigger

A barrel scintillator detector based on Hybrid Photo Diode (HPD) readout to be employed in the inner region of the FINUDA experiment is described. An array of 12 scintillator slabs of (200×31×2.3) mm3 is read by 24 HPDs. This device, designed to work in a 1.1 T uniform magnetic field, will provide a fast first level trigger to discriminate signal from background events and the start signal for TOF measurements and for the drift chambers. The overall performances of a module have been tested using minimum ionizing electrons from a 90Sr source.