A Perturbation Analysis of Changes in Prompt Fission Neutron Uranium-Logging Signals Produced by Trace Neutron-Absorbing Rock Constituents

A perturbation theory expression has been developed to predict the incremental detector output realized when traces of neutron-absorbing elements are present during prompt fission neutron uranium logging. The most restrictive constraint on the validity of the theory is that changes in the neutron flux caused by the presence of neutron absorbers must be small. Numerical evaluation of the theoretical expression appears feasible for experimental configurations that can be approximated by one-dimensional geometry.