Unlike x-rays, neutron sources have inherently low brightness and neutrons are very expensive to produce. The ideal scheme would be to optimize the performance of a neutron-scattering instrument and its optics to match the moderator characteristics during the instrument's design phase.
Users can track the history of a neutron as it journeys from the moderator to the detector.
Neutron-optic models describe neutron transport and scattering as neutrons interact with the optical elements and other components on their simulated journey through an instrument. NISP runs on UNIX, Linux, Windows, Mac, and DEC platforms. NISP has a tutorial to help users build their instruments or run experiments on existing models. A tutorial, a manual, and documentation are also available online. The pulse emitted by a moderator at a pulsed neutron source has a complicated dependence on time, energy, and direction of emission.