  A neutron time projection chamber can locate the approximate direction of a
neutron hot spot with high efficiency and a 4{\pi} field of view. The angular
resolution can be significantly improved by adding several plastic
scintillation detectors and using coincidence events. The specific performances
of such a coincidence imaging system are studied based on theoretical
calculations and experimental results. The calculated value of the angular
resolution is approximately 2{\deg} for the current system, which agrees well
with the experimental results and sets an upper limit for the angular
resolution of traditional back projection based online reconstruction methods.
Although the statistical iterative method can breakthrough this limit and
further improve the angular resolution, the time consumption is usually a
problem. The coincidence imaging system can be further optimized for future
applications based on the theoretical model.
