Development of a non-invasive method for the determination of the macroscopic neutron cross sections of a sample matrix in large-sample prompt-gamma neutron activation analysis

Abstract

In order to correct for neutron self-shielding in large-sample prompt gamma NAA, a method has been developed to determine the macroscopic scattering and absorption cross sections, i.e., ∑ a and ∑ s, using four Cu flux monitors placed around the sample. With Monte Carlo computations, the neutron densities throughout the sample and the resulting and the corresponding self-shielding factor as calculated from the ∑ a and ∑ s as obtained through the Cu monitors were compared to the true values. The derived ∑ a and ∑ s were found to be sufficiently accurate as long as ∑ t = ∑ a + ∑ s was less than 0.6 cm -1 and ∑ s/∑ t was greater than 0.1. © 2007 Akadémiai Kiadó.