  Scintillating fibre detectors combine sub-mm resolution particle tracking,
precise measurements of the particle stopping power and sub-ns time resolution.
Typically, fibres are read out with silicon photomultipliers (SiPM). Hence, if
fibres with a few hundred $\mu$m diameter are used, either they are grouped
together and coupled with a single SiPM, losing spatial resolution, or a very
large number of electronic channels is required. In this article we propose and
provide a first demonstration of a novel configuration which allows each
individual scintillating fibre to be read out regardless of the size of its
diameter, by imaging them with Single-Photon Avalanche Diode (SPAD) array
sensors. Differently from SiPMs, SPAD array sensors provide single-photon
detection with single-pixel spatial resolution. In addition, O(us) or faster
coincidence of detected photons allows to obtain noise-free images. Such a
concept can be particularly advantageous if adopted as a neutrino active
target, where scintillating fibres alternated along orthogonal directions can
provide isotropic, high-resolution tracking in a dense material and reconstruct
the kinematics of low-momentum protons (down to 150 MeV/c), crucial for an
accurate characterisation of the neutrino nucleus cross section. In this work
the tracking capabilities of a bundle of scintillating fibres coupled to
SwissSPAD2 is demonstrated. The impact of such detector configuration in
GeV-neutrino experiments is studied with simulations and reported. Finally,
future plans, including the development of a new SPAD array sensor optimised
for neutrino detection, are discussed.
