Ottawa Sand, Royer Dolomite and Dunite Sand as reference samples for the thermal neutron absorption cross-section

Thermal neutron absorption cross-section measurements on three samples supplied by the International Atomic Energy Agency are reported. The absorption cross-section was measured using a method developed at the Institute of Nuclear Physics in Krakow, Poland. The method consists of irradiation by a pulsed fast neutron beam of the system containing the investigated sample surrounded by an outer moderator. The decay constant of the thermal neutron flux in the system is measured as a function of the thickness of the moderator. The absorption cross-section of the sample is obtained by combining the experimental results with a theoretical calculation. Several independent assays were performed for each sample. The average values of the mass absorption cross-section (in units 10-3 cm2/g) are 2.45 + - 0.23 for Ottawa Sand, 2.71 + - 0.42 and 1.93 + - 0.28 for Royer Dolomite, and 3.72 + - 0.22 for Dunite Sand (at the 95% confidence level). The paper contains individual results of the mass and linear absorption cross-sections and the densities of the rocks for each assay. (author)