An experimental and theoretical study of neutron leakage and transport in a fast neutron moderator and flight-path arrangement

This paper reports on fast neutron moderators that are often used at intense accelerator-based neutron sources. It is known that grooved moderators provide greater neutron leakage currents than full moderators with flat surfaces of the same volume. Experimentalists are mainly interested in the neutron fluxes at the end of the flight paths, where experiments are normally located. To show that an optimized design of such assemblies can be done by Monte Carlo simulation, a moderator/flight-path assembly was built, and experiments were performed with different surfaces of the fast moderator. The Monte Carlo calculations fit the experiments with sufficient accuracy.