1. n. [Formation Evaluation]

A neutron interaction in which part of the kinetic energy lost by a neutron in a nuclear collision excites the nucleus. The excited nucleus will usually emit characteristic gamma rays upon de-excitation. Inelastic neutron scattering is possible only if the neutron energy exceeds a characteristic threshold for the element. Inelastic neutron scattering is the principle behind the carbon-oxygen log, which is used to determine water saturation behind casing.

See: chemical neutron source,  fast-neutron reaction,  neutron capture,  neutron generator,  neutron interactions,  water saturation