  We propose an alternative approach for the detection of fast neutrons in the
energy range from 10-4 to 5 MeV based on 10B-RPCs (hybrid double-gap Resistive
Plate Chambers with 10B4C neutron converters) surrounded by a polyethylene
moderator. The detection efficiency as a function of the neutron energy is
obtained in Monte Carlo simulations performed with the Geant4 toolkit for
several detector configurations. The thickness of the neutron converter is
optimized for the maximum efficiency. The results show that for this type of
detector it is possible to obtain an average detection efficiency larger than
50% with a weak dependence on the neutron energy. The dark count rate and gamma
sensitivity are also discussed.
