NIXE: Neutron Depth Profiling coupled with Particle Induced X-ray Emission

Abstract

A modification of the Neutron Depth Profiling (NDP) technique is proposed which uses the charged particle-induced X-ray emission generated from the light energetic ions produced in nuclear reactions to provide additional information about the depth profile of elements in the surface of a material. It is demonstrated that the particle-induced X-ray emission (PIXE) spectrum can also be measured with an NDP apparatus with the addition of an X-ray detector. By using coincidence counting methods, it is possible, in principle, to measure the elemental depth profile in the top few microns of a specimen. In this study, theoretical calculations and Monte Carlo radiation transport simulations were performed for 1400 keV alpha particles in a borosilicate glass material with three layers containing differing concentrations of Na2O, P2O5, B2O3 and SiO2. The production of K-shell X-rays for these elements was calculated from the production rate of alpha particles in (n, α) reactions, simulated using the Monte Carlo of N-Particle (MCNP6) radiation transport code. The main constraints on quantification limits and depth resolution for this technique depend on the material composition, detector efficiencies, and the neutron beam flux.