  An optimized design of a neutron detector based on timing RPCs (Resistive
Plate Chambers) with boron-10 neutron converters is presented. The detector is
composed of a stack of ten double gap RPCs with aluminium cathode plates coated
on both sides with $^{10}B_{4}C$. This design enables simultaneous
determination with high accuracy of both the neutron time-of-flight (down to ns
resolution) and the interaction position in 3D (down to 0.25 mm resolution
across and ~1 mm along the beam). It is shown that the detection efficiency can
approach 60% for neutrons with $\lambda$ = 4.7 \.A. A new geometry with less
material budget is introduced for the signal pick-up strip arrays. The results
of simulation-based optimization of the design are reported considering the
trade-off between the detection efficiency, the count rate capability and the
amount of elastic scattering on the detector components.
