Detection limits may be further improved by optimizing irradiation, decay, and counting times to the half-life of the element of interest. The use of loss free counting methods and high throughput detectors allow quantification at higher counting rates with minimal loss of signal or resolution, further improving detection limits. ![]() Quantification of elements is accomplished by comparison with standards usually irradiated along with the samples.ĭetection limits may be improved by the use of anticoincidence or coincidence counting techniques to improve signal to noise ratio. After a suitable decay period following irradiation, the nuclides of interest are determined by gamma ray spectroscopy using a high-resolution germanium detector with appropriate signal analyzer and electronics. Since the neutron flux is highly thermalized, single neutron capture reactions are dominant. During irradiation elemental nuclei capture neutrons and produce radioactive nuclei. Pneumatic tubes allow irradiation at two different reactor positions, at neutron fluence rates of 1 x 10 14 cm -2 s -1 and 3 x 10 13 cm -2 s -1. Samples are usually encapsulated in polyethylene or some other suitable packaging, packed into an irradiation capsule (usually a polyethylene “rabbit”) and irradiated in the reactor core. Instrumental neutron activation analysis (INAA), or sometimes referred to as simply NAA, is a method for determination of many elements at low levels in a wide variety of materials. ![]() Analytical capabilities and detection limits for elements by NAA
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