Monte Carlo models of neutron detection with organic scintillators

We describe the use of the MCNP-PoliMi code to simulate, on an event-by-event basis, the detection of neutrons by organic scintillators. This code keeps track of single neutron interactions, including the collision nucleus, the energy deposited, and the time distribution of collision events. We show that the total pulse-height response is given by the sum of many possible neutron histories, each composed of a certain number of neutron scatterings on hydrogen and/or on carbon. The simulated pulse-height distributions are compared to experimental data acquired using various neutron sources. Simulations and measurements of neutron pulse-height distributions are essential for neutron spectrum unfolding procedures. This work has applications in the areas of nuclear nonproliferation and homeland security.