Neutron Scattering - Scattering of Fast Neutrons

Scattering of Fast Neutrons

"Fast neutrons" (see neutron temperature) have a kinetic energy far above 1 eV. Their scattering by condensed matter (with nuclei having kinetic energies far below 1 eV) is in a good approximation an elastic collision with a particle at rest. At each collision the fast neutron transfers a significant part of its kinetic energy to the scattering nucleus; the more so the lighter the nucleus. In this way the neutron is slowed down until it reaches thermal equilibrium with the material in which it is scattered.

Neutron moderators are used to produce "thermal neutrons" that have kinetic energies below 1 eV (T < 500K). Thermal neutrons are used to maintain a nuclear chain reaction in a nuclear reactor, and as a research tool in neutron science comprising scattering experiments and other applications (see below). In the remainder of this article we will concentrate on the scattering of thermal neutrons.