Thermal NAA:

Thermal neutrons with energy 0.025 eV could induce radiative capture (n,γ) reactions in the target nuclei and delayed γ-rays from the sample are detected. An advantage of using thermal neutrons is their higher cross section compared to those for higher energy neutrons. At higher flux of thermal neutrons, TNAA offers potentially higher sensitivity for a large number of elements except lighter elements such as C, N, O etc. and potentially toxic elements such   as Tl, Pb, Ni, etc. TNAA could be used for the determination of concentration of up to 60 elements at trace and ultra trace level can be determined in a wide variety of samples.