International Research Fellowship Program: Search for Isotopes from Recent Nearby Supernova with Nearby Accelerator Mass

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0502034LevineThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a three-month research fellowship by Dr. Jonathan Levine to work with Drs. Jorge O. Fernandez-Niello and Andres Arazi at Laboratorio TANDAR, Comision Nacional de Energia Atomica Phycics in Buenos Aires, Argentina.Most meteorites that reach the Earth survive for a few thousands years, at most, before they are destroyed by erosion and weathering. The so-called "terrestrial ages" of particular meteorites, or the duration of time since a meteorite has fallen to Earth, can be calculated from the measured abundance of radioactive isotopes. Carbon-14 is used extensively for this purpose. However, some meteorites are old enough that no detectable carbon-14 remains. These rare meteorites are especially interesting for questions about how the fall-rate of different types of meteorites has changed over the last several tens of thousands of years, as well as for geological studies of the slowly-eroding regions where they are found. The investigators are attempting to determine the terrestrial ages of such old meteorites from the abundance of radioactive nickel-59 (half-life 76,000 years). They search for nickel-59 by accelerator mass spectrometry, which allows them to detect nickel-59 abundances lower than one part per trillion of the total nickel endowment of a specimen. They are working to further improve the sensitivity, by improving chemical separation, mass resolution, and ionic detection techniques. Nickel-59 offers greatest promise for dating meteorites collected from geological settings of extraordinary preservation, such as Antarctica, where meteorites are eroded much more slowly than elsewhere because of the dry climate.