-4- - Neutron Radiation

Abstract

This chapter discusses various aspects of neutron radiation. The chapter describes various sources, properties, and mechanisms of interaction of neutrons with matter. Neutron radiations are emitted when neutrons are ejected from the nuclei of atoms because of the reactions between the nuclei and particulate radiation. Neutrons are generally classified according to their kinetic energies: cold neutrons, slow (thermal) neutrons, slow (epithermal) neutrons, intermediate neutrons, fast neutrons, and high-energy (relativistic) neutrons. Neutrons can be produced by (1) alpha particle-induced nuclear reactions, (2) spontaneous fission, (3) neutron-induced fission, (4) photoneutrons, (5) accelerator sources, and (6) nuclear fusion. The lack of charge of a neutron makes it unable to cause any ionization directly in matter, unlike alpha and beta radiations. The potential for either nuclear fission or fusion depends on the stability of the atomic nucleus as measured by the binding energy per nucleon (B/A). The chapter concludes with a discussion on several mechanisms of interaction of neutrons with matter—such as elastic scattering, inelastic scattering, neutron capture, nonelastic reactions, and nuclear fission.