Paul Carpenter

CALCZAF, TRYZAF and CITZAF: The Use of Multi-Correction-Algorithm Programs for Estimating Uncertainties and Improving Quantitative X-ray Analysis of Difficult Specimens

Much work has been done in the last 50 years in developing comprehensive correction algorithms for quantitative electron microbeam analysis. A number of correction methods – both theoretically and empirically based – have been used, incorporating or parameterizing various compilations of physical constants like mass absorption coefficients and mean ionization potentials. There is no single, universally accepted correction method used for microbeam analysis and the correction programs employed by the commercial instrument manufacturers give different results for the same input data.

A Quantitative Method for Evaluating Regolith Simulants

The surface of rocky planets, moons and some other astronomical bodies have significant amounts of broken geologic materials. In the absence of more specific, applicable terminology, such material is generically termed regolith. Even on relatively simple bodies, like the Moon, the nature of the regolith is fairly complex. For mission development a regolith needs to be simulated; and many have been created for the Moon and Mars. But there is no generally accepted method to express the quality of a simulant. This paper proposes a method for ascertaining the quality of a simulant through the use of Figures‐of‐Merit. In support of NASA’s exploration mission this method has been implemented. MSFC has creating a suite of simulants whose compositions cover the samples returned by the Apollo missions. These are termed Standard Lunar Regolith Simulant (SLRS) materials. The approach is adaptable, extensible and evolutionary. It is considered highly applicable to other regoliths of interest.

Computed Tomography and its Application for the 3D Characterization of Coarse Grained Meteorites

With judicious selection of parameters, computed tomography can provide high precision density data. Such data can lead to a non-destructive determination of the phases and phase distribution within large solid objects. Of particular interest is the structure of the Mundrabilla meteorite, which has 25 volumes, percent of a sulfide within a metallic meteorite. 3D digital imaging has enabled a quantitative evaluation of the distribution and contiguity of the phases to be determined.

Microbeam Analysis Society

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Improvements in Electron-Probe Microanalysis: Applications to Terrestrial, Extraterrestrial, and Space-Grown Materials

Improvement in the accuracy of electron-probe microanalysis (EPMA) has been accomplished by critical assessment of standards, correction algorithms, and mass absorption coefficient data sets. Experimental measurement of relative x-ray intensities at multiple accelerating potential highlights errors in the absorption coefficient. The factor method has been applied to the evaluation of systematic errors in the analysis of semiconductor and silicate minds. Accurate EPMA of Martian soil stimulant is necessary in studies that build on Martian rover data in anticipation of missions to Mars.