Fast-neutron reaction

{
  "id": "MLC-T-OAG-001374",
  "term": "Fast-neutron reaction",
  "field": "Oil and gas",
  "definition": "An interaction between fast neutrons emitted by a logging source and nuclei in the formation, in which the neutrons lose energy by elastic scattering, mainly off hydrogen, and by inelastic scattering off heavier nuclei such as carbon, oxygen and silicon, which excites the nucleus. Hydrogen has no excited states, so it slows neutrons only through elastic collisions, but those are the most efficient because its mass is nearly equal to that of a neutron. The resulting slowing down and later thermal capture are what neutron porosity tools measure.",
  "subject": "Formation Evaluation",
  "url": "https://mlchart.com/terminology/oil-and-gas/fast-neutron-reaction/"
}