14 Mev Neutron Activation Cross-Sections

Neutron activation analysis is generally carried out with reactor neutrons using the (n,γ) reaction. However, for cases where the (n,γ) reaction products have unsuitable decay properties, or if due to low cross-section the process is not very specific, activation with 14 MeV neutrons and identification of the (n,x) reaction products may be of advantage. This is particularly true for the light elements where fast neutron activation is often considerably more specific. Thus, with thermal neutrons only macro amounts of nitrogen and oxygen can be determined via the ¹⁵N(n,γ)¹⁶N and ¹⁸O(n,γ)¹⁹O reactions, respectively, whereas use of 14 MeV neutrons enables the detection of parts per million amounts of those two elements via the reactions ¹⁴N(n,2n)¹³N and ¹⁶O(n,p)¹⁶N, respectively. Similarly, fluorine, sodium, and silicon can be conveniently determined using fast neutron activation via the reactions ¹⁹F(n,2n)¹⁸F, ²³Na(n,α)²⁰F and ²⁸Si(n,p)²⁸Al, respectively. In the medium and heavy mass regions as well, in several specific cases, 14 MeV neutron activation analysis may be advantageous and more convenient than thermal neutron activation analysis. The determination of iron, niobium, and thallium via the reactions ⁵⁶Fe (n,p)⁵⁶Mn, ⁹³Nb(n,2n)⁹²Nb, and ²⁰³Tl(n,2n)²⁰²Tl, respectively, constitute some typical examples.