A neutron detector based on a polystyrene hydrogenous scintillator is descr
ibed. The detector allows one to measure incident neutron fluxes with inten
sities ranging from 10(3) to 2 x 10(5) neutron/s with a time resolution of
4 ms. The detector operation is demonstrated in experiments performed at th
e AMBAL-M installation and the IK-50 test bench for recording fluxes of fas
t neutrons generated in the injector tract of a deuterium beam as a result
of the D+ + D --> n + He-3 thermonuclear reaction.