Automatic and Accurate Sample Positioning in k₀-NAA and Semi-parametric Efficiency Normalization for Different Counting Positions

An automatic sample changer and an accurate sample positioning system were developed for γ-spectrum measurements in general and k₀-NAA in particular. Full energy peak efficiencies for radionuclides with arbitrary decay schemes were calibrated over 0-280 mm source-detector distances. A semi-parametric method was established for efficiency normalizations among different counting positions-parametric effective interactive depth method for efficiency normalizations of “far” (true coincidence effect negligible) counting positions, and experimentally determined “rack-ratio” of a given γ-ray from a given nuclide for that of “near” (true coincidence effect worth considering) counting positions.