A system for the determination of silicon in the human lung using neutrons from A 2MV Van de Graaff generator

Abstract

Neutron activation analysis, using inelastic scattering, provides a quantitative, non-invasive technique of studying silica burdens and is potentially useful as a screening procedure for occupationally exposed workers. In this method, silicon is measured using the fast neutron inelastic scattering reaction²⁸Si(n,n′ γ)²⁸Si which emits 1779 keV γ-rays. The method requires a source of fast neutrons (> 2MeV). A 2MV Van de Graaff generator has been developed to produce a pulsed beam of 5.2 MeV neutrons. The pulsed beam has the advantage of improving measurement sensitivity by separating in Bone the inelastic scattering γ-rays from those due to thermal-neutron capture reactions. The incident neutron energy was chosen to maximise the silicon γ-ray count rate, while keeping the signal from the competing reaction³¹P(n,α)²⁸Al negligible.