Activation Analysis (AA):

Techniques of activation analysis include the use of nuclear reactions induced through neutrons, photons or charged particles like as protons, deuterons, alpha particles and other heavy ions in a nuclear reactor or accelerator facility to produce radionuclides. When a target element is bombarded with a neutron beam, a compound nucleus with higher mass number in excited state is formed. It may undergo instantaneous decay to form a product nucleus finally emitting delayed β or γ rays. This technique is called neutron activation analysis (NAA). However, if the bombarding particle is photon, it is known as photon activation analysis (PAA) or if the sample is bombarded along with charged particles like as deuterons, protons or alpha particles then it are called charged particle activation analysis (CPAA). If bombarding particle induces x-ray emission via interaction with the electron shells of the target element, the analytical method is known as particle induced x-ray emission (PIXE). Of all the activation analysis techniques, NAA using reactor neutrons remains the most hugely used analytical method. The method of NAA was discovered through George de Van Hevesy and Hilde Levy in 1936 and used for the determination of Dy in a rare earth mineral by using ²²²Rn.Be neutron source. Later charged particle activation analysis (EPAA) was discovered by G T Seabory and Livingood in 1938 for the determination of Ga impurity in iron by deuteron induced reaction. Here we shall elaborate principle, methodology involving instrumentation and applications of NAA in detail.