ABSTRACT
First discovered by Chadwick in 1932, the neutron and its interaction with matter have ever since been the subject of intense study. Much of physics in the 1930s was devoted to working out the behavior of neutrons in interaction with nuclei and in their transport through matter. The behavior of neutrons passing through matter is sharply distinguished from that of all other projectiles in that the latter interact primarily with atomic electrons in the target material, with their relatively small nuclear interaction a small correction. The energy range designations are not precise. Their names are more suggestive of the consequences of reactions of neutrons in that energy range, rather than that of the range itself. Unwanted neutrons, for example, those escaping from a nuclear reactor, can be dangerous to humans or destructive to electronic equipment if in sufficient numbers.
