Behavior of Dark Scattered Neutrons in Plastic Scintillators

The Modular Neutron Array (MoNA) is used in experiments of nuclei approaching the neutron drip line. These experiments often rely on simulations for the interpretation of their results. The purpose of this experiment is testing the accuracy of these simulations, especially dark scattering: A phenomenon where a neutron scatters off a hydrogen or carbon atom, but does not produce enough light to be detected. This experiment was run by the MoNA collaboration at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center; the setup consisted of 16 MoNA detectors. One detector was placed directly in front of the neutron beam as a target. The other 15 detectors were arranged in a staircase downstream of the target to detect neutrons scattered from the target. The main sources of background in this experiment consist of cosmic muons, and neutrons which exit the collimator at an angle, avoiding the target detector but still hit the staircase. These sources of background do not exist in simulation, so it is necessary to remove them from the data. This background is indistinguishable from dark scattering, so creative methods are required to eliminate it. These methods of background removal and preliminary scattering results will be presented.