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Abstract  

A suite of shallow and deep subsurface waters from southwestern Illinois has been analyzed for chlorine (CT), bromine (Br), and sodium (Na+) using three different methods. Cl and Br were analyzed by ion chromatography (IC) and neutron activation analysis (NAA). Na was analyzed using inductively coupled plasma-atomic emission spectrometry (ICP-AESS) and NAA. In addition, five water standards were prepared with compositions over the range of Cl, Br, and Na concentrations in the natural waters were analyzed using the same methods. Analytical results for the prepared standards by the different methods were in good agreement. However, analytical results on natural waters yielded generally poor agreement between the methods. Our results suggest that solute concentrations and ratios between major solutes in subsurface waters determined by IC and ICP-AES may involve substantial laboratory error.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Lindstrom, R. Zeisler, D. Vincent, R. Greenberg, C. Stone, E. Mackey, D. Anderson, and D. Clark

Abstract  

An instrument for neutron capture prompt gamma-ray activation analysis (PGAA) has been constructed as part of the Cold Neutron Research Facility at the 20 MW National Institute of Standards and Technology Research Reactor. The neutron fluence rate (thermal equivalent) is 1.5·108 n ·cm–2·s–1, with negligible fast neutrons and gamma-rays. With compact geometry and hydrogen-free construction, the sensitivity is sevenfold better than an existing thermal instrument. Hydrogen background is thirtyfold lower.

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Abstract  

Analyses for certification have been made for the determination of 30 elements in the National Institute of Standards and Technology (NIST) Tomato Leaves renewal reference material, SRM 1573a. Three of the analytical techniques used were instrumental neutron activation analysis (INAA), radiochemical neutron activation analysis (RNAA), and prompt gamma activation analysis (PGAA). These techniques provided data on 19 elements by INAA, 10 elements by PGAA, and 7 elements by RNAA, with some overlap between techniques. For example, INAA was able to obtain overall analytical uncerainties (at the 95% confidence level) averaging ±2.2% for major and minor constituents (Ca, Mg, K), ±3.3% for constituents from 1 to 1000 g/g (Na, Fe, Al, Mn, Ba, Zn, Rb, La, Cr), and ±6.4% for elements between 10 and 1000 ng/g (Co, V, Se, Th, Sc, Sb), using sample dry weights of approximately 150 mg. These analyses represent the most extensive use to date of nuclear analytical techniques in the certification of a trace element SRM at NIST.

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Abstract  

An instrumental neutron activation analysis (INAA) technique, based on the19F(n,)20F reaction, has been development for the determination of fluoride in bone. The purpose was to study fluoride distribution in different kinds of bone samples using a rabbit model. The rationale for the study stems from the posible correlation between fluoride in bone and osteoporosis. The sodium concentration in the bone was used to correct the20F peak area for the23F(n,)20F contribution. Two secondary standards, teflon tape and teflon coated dacron line, were used to quantify fluoride concentration. They proved to be stable and consistent with respect to their fluoride concentration. Bone specimens from 10 sites and two tooth samples were analyzed for fluoride. Fluoride concentration ranged from 305 ppm in the tibia long bone to 585 ppm in the humerus trochanter end and the magnitude of fluoride concentration levels is age depdentent. The detection limit of the fluoride is approximately 5 ppm using a 100 mg bone sample.

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Abstract  

A facility for neutron-capture γ-ray spectroscopy for analytical purposes has been developed and tested at the National Bureau of Standards reactor. The system consists of an internal beam tube with collimators, an external beam tube and irradiation station, a Compton-suppressed Ge(Li) γ-ray detection system, and a minicomputer-based data-collection and-analysis system. Detection limits have been established for many elements and errors arising from neutron self shielding, γ-ray peak overlap, neutron beam variations, and sample matrix evaluated.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: W. Cunningham, D. Anderson, W. Lamont, P. South, M. Rury, G. Beachley, and J. Ondov

Abstract  

Transportable radioanalytical systems were assembled and tested for quantitative determination of γ-emitting radionuclides and screening of β-emitting radionuclides. Standard operating procedures (SOPs), including instructions for assembly, disassembly, operation, sample collection and analysis, and all other procedures needed, were developed. Foods, as well as National Institute of Standards and Technology, International Atomic Energy Agency, and in-house Reference Materials were analyzed. An SOP for γ-emitting radionuclides was successfully tested at 3 locations.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Ely, K. Anderson, D. Bates, R. Kouzes, C. Lo Presti, R. Runkle, E. Siciliano, and D. Weier

Abstract  

Plastic scintillator material is often used for gamma-ray detection in many applications due to its relatively good sensitivity and cost-effectiveness compared to other detection materials. However, due to the dominant Compton scattering interaction mechanism, full energy peaks are not observed in plastic scintillator spectra and isotopic identification is impossible. Typically plastic scintillator detectors are solely gross count detectors. In some safeguards and security applications, such as radiation portal monitors for vehicle screening, naturally-occurring radioactive material (NORM) often triggers radiation alarms and results in innocent or nuisance alarms. The limited energy information from plastic scintillator material can be used to discriminate the NORM from targeted materials and reduce the nuisance alarm rate. An overview of the utilization of the energy information from plastic scintillator material will be presented, with emphasis on the detection capabilities and potential limitations for safeguards and security applications.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: E. Mackey, D. Anderson, H. Chen-Mayer, R. Downing, R. Greenberg, G. Lamaze, R. Lindstrom, D. Mildner, and R. Paul

Abstract  

At the National Institute of Standards and Technology, there are two techniques for chemical analysis that use neutron beams from the reactor for target irradiation: neutron depth profiling (NDP) and prompt -ray activation analysis (PGAA). There are two facilities for each technique, one equipped with a thermal neutron beam and the other, with a cold neutron beam. In addition, focused beams of cold neutrons will be used to measure the two-dimensional element distributions by PGAA and three-dimensional distributions by NDP. This paper includes a brief description of the facilities, the measurement capabilities of each, some recent applications of NDP and PGAA, and neutron focusing as applied to these techniques.

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Thin-layer chromatography and electrophoresis, with their long histories of simple and effective characterization of chemical mixtures, have motivated an effort to combine these techniques. Simultaneous chromatography and electrophoresis (SCE) utilizes an electric field orthogonal to capillary action or pressure flow to achieve a single-step two-dimensional separation. In this work, plate conditioning and pressurized simultaneous chromatography and electrophoresis (pSCE) are introduced. These improvements reduce separation times and concurrently increase or maintain separation quality as described by visual comparisons, nearest neighbor distance descriptors, and relative spot capacities.

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