APPLICATIONS OF MONTE-CARLO DIFFERENTIAL NEUTRON SENSITIVITY CALCULATIONS TO GEOPHYSICAL MEASUREMENTS

The spatial responses of neutron porosity measurements are of considerable interest for understanding the physics of neutron logging tools. A generalized technique implemented through modification of the MCNP transport code now permits sensitivity functions to be computed for nearly any type of nuclear well-logging response, as well as for a variety of other radiation devices. Analyses of the spatial responses of two logging tools using sensitivity function calculations are presented in this paper. The results provide new insight on the physics of these measurements. The accuracy of the calculations is demonstrated through a comparison with empirical data. This new ability to compute spatially-distributed sensitivity functions for neutron interactions will be an important tool for the design and interpretation of future radiation-based measurements.