Nuclear logging tool. At least some of the illustrative embodiments are methods comprising placing a logging tool within a borehole proximate to an earth formation, releasing energetic neutrons from the logging tool, and receiving (at a detector within the logging tool) gamma returns indicative of interactions of the neutrons with elements of the logging tool and elements of the formation, and the gammas indicative of neutron interactions with elements of the logging tool are substantially free from gammas indicative of interactions with iron atoms.