Fast NAA:
The fast neutrons encompass the widest range of energy, 0.5 - 20 MeV. Neutrons of this energy range do not induce (n,γ) reactions but instead are responsible for (n, p), (n, α), (n, n') and (n, 2n) reactions. Mostly FNAA is performed using 14 MeV neutrons. There are specially useful for the determination of oxygen using the reaction 16O (n, p)16N.