NEUTRON INTERACTIONS

Atomic and Nuclear Physics DOE-HDBK-1019/1-93 NEUTRON INTERACTIONS NEUTRON INTERACTIONS Neutrons can cause many different types of interactions. The neutron may simply scatter off the nucleus in two different ways, or it may actually be absorbed into the nucleus. If a neutron is absorbed into the nucleus, it may result in the emission of a gamma ray or a subatomic particle, or it may cause the nucleus to fission. EO 3.1 DESCRIBE the following scattering interactions between a neutron and a nucleus: a. Elastic scattering b. Inelastic scattering EO 3.2 STATE the conservation laws that apply to an elastic collision between a neutron and a nucleus. EO 3.3 DESCRIBE the following reactions where a neutron is absorbed in a nucleus: a. Radiative capture b. Particle ejection Scattering A neutron scattering reaction occurs when a nucleus, after having been struck by a neutron, emits a single neutron. Despite the fact that the initial and final neutrons do not need to be (and often are not) the same, the net effect of the reaction is as if the projectile neutron had merely "bounced off," or scattered from, the nucleus. The two categories of scattering reactions, elastic and inelastic scattering, are described in the following paragraphs. Elastic Scattering In an elastic scattering reaction between a neutron and a target nucleus, there is no energy transferred into nuclear excitation. Momentum and kinetic energy of the "system" are conserved although there is usually some transfer of kinetic energy from the neutron to the target nucleus. The target nucleus gains the amount of kinetic energy that the neutron loses. Rev. 0 Page 43 NP-01