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  • Author or Editor: W. Zoller x
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Abstract  

Atmospheric particulate samples were collected at the geographic South pole, using cellulose and polycarbonate filters and cascade impactors. The samples were analysed for 40 elements by instrumental neutron activation analysis. From the filter samples atmospheric concentrations for 33 elements could be obtained. The highest atmospheric concentrations were found for S: 49 ng/standard cubic meter (SCM) of air, Na: 3.3 ng/SCM and Cl: 2.6 ng/SCM. In the cascade impactor samples, only a few elements were observed above blank. For these elements it could be concluded that they are associated for over 80–90% with submicron size paricles.

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Abstract  

Neutron-capture prompt γ-ray analysis (PGAA) is an exceptionally good method for the determination of the major and minor elements Na, Mg, Al, Si, K, Ca, Ti, Mn and Fe in most geological matrices. The trace elements H, B, S, Cl, Cd, Sm and Gd can often be readily measured in most geological materials. This technique was applied to volcanic ash samples collected in Washington and Montana by various groups following the May 18 eruption of the Mt. St. Helens volcano, as well as to several particulate samples collected at altitudes between 13 and 18 km by a NASA U-2 research aircraft. Groundfall ash samples show distinct elemental variations versus distance from the volcano. For example, Si/Al ratios vary from 2.85 near the volcano to about 3.70 at≽400 km to the east. Samples collected sequentially at a given location (Almira, Washington) also exhibit variations in the elemental ratios. These sequential samples were also subjected to leaching studies to determine soluble B, Cl and S. On the average, PGAA is able to account for 99.4±1.7% of the mass of each sample when the elements are considered to be in their common oxide forms. The stratospheric samples were collected May 19 on IPC cellulose filters on apparatus in a wing tank of the U-2. The PGAA results indicate that the sample from the greatest altitude resembles ashfall near the volcano, while those at lower altitudes somewhat resemble more distant ashfall.

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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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