Neutron Computed Tomography

(Students Maris Tabor and Nik Huerta are working on this project with post doc Martin Wilding and Sasha Tsapin at JPL. Funding is provided by UCDavis, NASA Exobiology, and DOE.)

Hydrogen scatters neutrons much more effectively than common rock-forming atoms such as oxygen, silicon, alluminum, etc. Thus, digital imaging of the attenuation of neutrons through a rock sample can highlight areas with high concentrations of scattering atoms such as those in organics (which contain H). Using computational techniques similar to those used in X-ray CT, we can reconstruct the 3-d distribution of organics in rocks. Currently, we are developing new callibration and processing techniques to develop astrobiological applications for neutron CT. We will apply these techniques to various problems including studies of endolithic communities, ancient microbialites, and porosity in rocks. (See Wilding et al. 2002 abstract for preliminary results.)

A transparent volume of a 1.5 cm sample of sandstone from the Negev Desert. The pink areas are more attenuating and correlate to areas with green pigment from an endolithic bacterial community.

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Dawn Y. Sumner
Department of Geology
University of California
Davis, CA 95616