Overview
Neutron activation analysis (NAA) is a method for quantitative composition analysis of chemical elements based on the conversion of stable nuclei in the sample to radioactive nuclei by nuclear reactions, followed by the quantitation of the reaction products via their gamma radiations. The k0-standardized neutron activation analysis (k0-NAA), combined with high-resolution and highthroughput gamma-ray spectrometry, offers mostly non-destructive, multi-elemental analysis for many branches of science and technology. NAA has inherently favorable characteristics, negligible matrix effect, excellent selectivity and high sensitivity. Even small amount (few tens of milligrams) of samples (mostly solid) can be measured, in which about 35–75 elements in less than 0.01 μg quantities can be determined.
Technical details
Samples for NAA are irradiated with thermal neutrons. Short and long time irradiations are possible in two designated vertical channels of the reactor. Short irradiations are done by means of a pneumatic rabbit system, whereas samples for long irradiations are loaded into the rotating channel of Budapest Research Reactor. The gamma-rays emitted from the sample are counted in low-level gamma-spectroscopic counting chamber to reduce the external background. In our NAA laboratory there are three low-level gamma-spectroscopic chambers, which are built from pre-World War II steel (free of any manmade radioactivity), have 10 cm thick wall covered with 2 mm thick Cu-layer inside to attenuate the X-rays. Two high-purity Ge detectors and two digital gamma spectrometers are used to detect the gamma-rays and to collect the spectra. The spectra are evaluated with the gamma spectroscopy package Hyperlab 2013.1. This includes automatic peak search, energy calibration the nonlinearity option, and net peak area computation, efficiency correction. For quantitative evaluation, the KayZero for Windows 3 program is used, based on the k0 standardization.
Further reading
- László Szentmiklósi, Dénes Párkányi, Ibolya Sziklai-László, Upgrade of the Budapest neutron activation analysis laboratory, J. Radioanal. Nucl. Chem. (2016) 309 91–99 DOI: 10.1007/s10967- 016-4776-7