Most neutron activation analysis is performed with fission reactors, isotope sources, or fusion neutron sources. Among these techniques, nuclear reactors produce the highest neutron output, but are very limited by their large size and high logistical overhead. Isotope sources rely on neutron emitting elements such as Californium-252, many of which are synthetic, have a relatively short half-life, and can be difficult to acquire. Fusion neutron sources, which produce neutrons by combining atoms of deuterium or tritium, run the gamut in both size and neutron output. For some purposes, such as oil well logging, a fusion neutron source small enough to fit on a benchtop is extremely useful for neutron activation analysis. However, for other needs, a more powerful source of neutrons with a larger neutron output is required.
What Is Neutron Activation Analysis (NAA)?
Neutron activation isn’t always an undesirable event. Not only is it the cornerstone of the same nuclear fission reactions we rely on to produce energy, it is also actually a very useful tool for materials evaluation. When radionuclides expels excess energy in the form of, for example, gamma rays, how much energy they expel differs depending on the elements present.
Neutron Activation Analysis Definition
Neutron Activation Analysis is a method used to determine the elemental composition of a material by analyzing the different energies produced during neutron activation.
Different radionuclides release different energies of gamma radiation, and by measuring the gamma ray energies produced by neutron activation, you can actually determine a material’s multi element composition – specifically, the amounts of each element it contains, including trace elements (as in trace element analysis). Neutron activation analysis is a very sensitive and precise method of materials analysis for detecting trace elements present in a material, especially useful considering trace elements can be tough to detect under certain thresholds using other means.
Neutron activation analysis can be done with both a thermal neutron source, which produces low energy neutrons, or with fast neutrons, or high energy neutrons. High energy neutrons interact with an element’s atomic nuclei in a slightly different way than low energy neutrons. Depending on the size and density of the material, either a thermal neutron source or fast neutrons can be better suited for neutron activation analysis.
Phoenix Neutron Activation Case Studies
At Phoenix, we use our high neutron flux neutron generators to induce neutron activation mainly for application in nondestructive testing, such as radiation effects testing, in which materials irradiated by neutron radiation for sustained periods in order to test how well they function in high-radiation environments and determine at which point radiation results in a loss of structural integrity or function.
By configuring our high neutron flux neutron generators to produced pulsed fusion output instead of sustained output, therefore releasing large amounts of neutron radiation in very short bursts, our systems can be used for other applications of neutron activation analysis as well.
In 2019, Phoenix installed a radiation effects testing system for a European defense agency, which will allow them to perform radiation survivability testing on the electronic components without the need for a nuclear reactor.
Neutron activation is a key component in Phoenix’s prototype standoff IED detection system, NEMESIS. NEMESIS is a prototype mobile deuterium-deuterium neutron generator specially configured for mobility, designed to be installed at the head of a military convoy and used to scan ahead for hidden IEDs by producing a pulsed neutron output and detecting the resulting gamma radiation.
To inquire about purchasing a neutron generator system for neutron irradiation or about Phoenix’s neutron activation analysis services, contact our applications specialists: