MEASUREMENT OF THERMAL-NEUTRON ABSORPTION CROSS-SECTION IN SELECTED GEOCHEMICAL REFERENCE MATERIALS

The thermal neutron absorption cross-section (Sigma) of a sample is a measure of its ability to absorb neutrons and is a linear function of its total chemistry, Sigma is measured automatically by some downhole logging tools and is an important parameter for the lithological chara cterisation of formations, As part of a programme to accurately determ ine the Sigma of lithologies commonly encountered in the Ocean Drillin g Program, it was necessary to evaluate the measurement of Sigma and t his was, in part, achieved by measuring Sigma on a number of geochemic al reference standards. Computed and measured Sigma values are reporte d here for thirteen geochemical reference standards.