  Plastic scintillator detectors have been extensively used in particle physics
experiments for decades. A large-scale detector is typically arranged as an
array of staggered long bars which provide a fast trigger signal and/or
particle identification via time-of-flight measurements. Scintillation light is
collected by photosensors coupled to both ends of every bar. In this article,
we present our study on a direct replacement of commonly used vacuum
photomultiplier tubes (PMTs) by arrays of large-area silicon photomultipliers
(SiPMs). An SiPM array which is directly coupled to the scintillator bulk, has
a clear advantage with respect to a PMT: compactness, mechanical robustness,
high PDE, low operation voltage, insensitivity to magnetic field, low material
budget, possibility to omit light-guides. In this study, arrays of eight 6 x 6
mm2 area SiPMs were coupled to the ends of plastic scintillator bars with 1.68
m and 2.3 m lengths. An 8 channel SiPM anode readout ASIC (eMUSIC) was used for
the readout, amplification and summation of signals of individual SiPMs. Timing
characteristics of a large-scale detector prototype were studied in test-beams
at the CERN PS. This technology is proposed for the ToF system of the ND280/T2K
II upgrade at J-PARC and the timing detector of the SHiP experiment at the CERN
SPS.
