Neutron Activation Analysis (original) (raw)
2014, Encyclopedia of Scientific Dating Methods
Neutron activation analysis is a chemical analysis technique that may be used to determine the average (bulk) concentrations of major, minor, and trace elements in a sample. It may be used to measure the concentration of a single element or, more often, to measure the concentrations of many elements, as part of a chemical characterization of a set of samples to determine chemical similarities or differences. Samples may be liquid (aqueous or organic) or solid (e.g.The most common form of neutron activation analysis is instrumental neutron activation analysis. In this, a suitably encapsulated, weighed amount of the sample to be analyzed is sent, pneumatically or manually, into an irradiation site of a research nuclear reactor, and is bombarded by neutrons with a broad range of energies that the reactor produces.
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Neutron activation analysis and results
Terracotta Statues and Figurines of Cypriote Type Found in the Aegean: Provenance Studies, 2009
From each ofthe ceramic figurines selected for analysis, a small portion ofapproximately 0.3 g was removed after cleaning the surface of the object, homogenized and kept in polyethylene vials. Chemical elemental analysis was performed by neutron activation (NAA) at the University of Missouri Research Reactor. Samples and standards for NM were prepared for long irradiation by weighing about 100 mg of powder into high-purity quartz vials. Standards were made using SRM-1633a Fly Ash and SRM-688 Basalt Rock; quality control samples were made using Ohio Red Clay and SRM-278 Obsidian Rock. All sample weights were recorded to the nearest 0.01 grams.
Chapter 6 Concepts , Instrumentation and Techniques of Neutron Activation Analysis
2013
Following the discovery of neutron by J. Chadwick in 1932 (Nobel prize, 1935) and the re‐ sults of F. Joliot and I. Curie in 1934, neutron activation analysis was first developed by G. Hevesy and H. Levi in 1936. They used a neutron source (226Ra + Be) and a radiation detec‐ tor (ionization chamber) and promptly recognized that the element Dy (dysprosium) in the sample became highly radioactive after exposure to the neutron source. They showed that the nuclear reaction may be used to determine the elements present in unknown samples by measuring the induced radioactivity.
2012
This thesis encompasses the experimentation and development of neutron activation analysis protocols for the University of Utah Nuclear Engineering Program (UNEP). The University of Utah TRIGA Reactor (UUTR) was used as a neutron source to activate various materials to examine the inorganic elements. The Activity Estimator calculator was developed to approximate the activities of activated isotopes. Gamma ray activities, from activated samples, were acquired and measured on high purity germanium gamma spectroscopy detectors. Using the data collected from the gamma spectroscopy activated isotopes were identified and quantified. The activities from the identified isotopes were used to calculate the elemental concentrations of the sample materials using the Elemental Concentration Calculator and SRM Ratio Calculator. Complete NAA protocols and procedures were developed for a wide variety of materials and uses such as: criminal forensics, metals in soil, rock and water as well as minerals in fruits and vegetables.
Neutron activation analysis: A primary method of measurement
Spectrochimica Acta Part …, 2011
Neutron activation analysis (NAA), based on the comparator method, has the potential to fulfill the requirements of a primary ratio method as defined in 1998 by the Comité Consultatif pour la Quantité de Matière-Métrologie en Chimie (CCQM, Consultative Committee on Amount of Substance-Metrology in Chemistry). This thesis is evidenced in this paper in three chapters by: demonstration that the method is fully physically and chemically understood; that a measurement equation can be written down in which the values of all parameters have dimensions in SI units and thus having the potential for metrological traceability to these units; that all contributions to uncertainty of measurement can be quantitatively evaluated, underpinning the metrological traceability; and that the performance of NAA in CCQM key-comparisons of trace elements in complex matrices between 2000 and 2007 is similar to the performance of Isotope Dilution Mass Spectrometry (IDMS), which had been formerly designated by the CCQM as a primary ratio method.
Neutron activation for precise nuclear data
Journal of Radioanalytical and Nuclear Chemistry, 1997
Techniques for extracting neutron flux parameters pertaining to the irradiation positions and nudear data pertaining to the isotopes concerned from measured reaction rates have been developed. An adjustment procedure based on the generalized least squares method which incorporates the evaluated literature nuclear data, estimates of flux parameters and the experimentally measured reaction rates using high resolution `/-ray spectrometry is applied. More precise values of the nuclear data, i.e., thermal neutron cross sections, resonance integrals and '/-ray emission probabilities are thus generated. The irradiation of a nmlli-element standard (MES) containing 24 dements is carried out in six different positions in two diverse types of reactor in the UK and Russia. It is shown that the improvement in nuclear data is revealed in more than 90% of the cases. Its equivalent for cadmium covered activity is given by:, Rcd=llNaOe.'I~'~g +f ~(O~) + (2)
Selection Criteria for Radionuclide of Interest in Neutron Activation Analysis
Nucleus, 2021
This paper describes general selection criteria for suitable activation products to get maximum signal to noise ratio in minimum time. The detection sensitivities for 71 elements which exist in nature, with respect to neutron activation analysis, have been calculated and presented. The paper defines the sensitivity as log (peak area/weight) produced for different radionuclides suitable for activation analysis using five sets of experimental conditions. Although, the current sensitivity factors have been calculated for miniature neutron source reactor (MNSR) having thermal neutron flux of 10 12 cm-2 s-1 ; however, the general pattern of elemental sensitivities will not be affected drastically by changing reactor type. Normalized peak areas have also been presented for the identification of suitable activation products. These normalized areas are independent of experimental conditions used and are therefore general in nature. Finally, real data have been presented from our previous studies, which confirm present findings and provide actual irradiation times along with useful gamma-rays used in the analysis.
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