  The next generation of very-short-baseline reactor experiments will require
compact detectors operating at surface level and close to a nuclear reactor.
This paper presents a new detector concept based on a composite solid
scintillator technology. The detector target uses cubes of polyvinyltoluene
interleaved with $^6$LiF:ZnS(Ag) phosphor screens to detect the products of the
inverse beta decay reaction. A multi-tonne detector system built from these
individual cells can provide precise localisation of scintillation signals,
making efficient use of the detector volume. Monte Carlo simulations indicate
that a neutron capture efficiency of over 70% is achievable with a sufficient
number of $^6$LiF:ZnS(Ag) screens per cube and that an appropriate segmentation
enables a measurement of the positron energy which is not limited by gamma-ray
leakage. First measurements of a single cell indicate that a very good
neutron-gamma discrimination and high neutron detection efficiency can be
obtained with adequate triggering techniques. The light yield from positron
signals has been measured, showing that an energy resolution of
14%/$\sqrt{E({\mathrm{MeV}})}$ is achievable with high uniformity. A
preliminary neutrino signal analysis has been developed, using selection
criteria for pulse shape, energy, time structure and energy spatial
distribution and showing that an antineutrino efficiency of 40% can be
achieved. It also shows that the fine segmentation of the detector can be used
to significantly decrease both correlated and accidental backgrounds.
