Acquisition of a New TIMS for Ocean and Earth Sciences at the University of Florida

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9601872 Mueller This proposal seeks funding to support 50% of the cost of acquiring and operating a state-of-the-art thermal ionization mass spectrometer (TIMS) for the Geology Department of the University of Florida. The proposed instrument will provide enhanced performance in three areas: 1) The instrument will be capable of providing extended dynamic range (10 ) through the ability to measure sample ion beans with both Faraday and electron multiplier- or scintillation - type detectors simultaneously. This capability is essential for utilizing systems in which the abundance of individual isotopes, including tracers, exceeds the dynamic range of Faraday detectors alone. 2) The instrument will be capable of providing high abundance sensitivity at high mass. This extended capability, relative to traditional TIMS configurations, is also necessary for accurate measurements in the U-Th series and provides benefits in lower mass systems such as Ca. Recent developments in the use of retarding potential lens can provide this capability without the need (and cost) of large, double focusing configurations; 3) The instrument will be capable of high precision isotopic ratio measurements in static mode. Measurement in this mode is necessary in order to combine the advantages of increased dynamic range and extended abundance sensitivity to provide maximum accuracy for small samples, e.g., those containing only picogram (10 g) quantities of Pb, and those with low ionization efficiencies, e.g., Th. Specific applications that will benefit include the analysis of U-series isotopes for recent geochronology; the analysis of individual zircon crystals or parts of crystals for geochronologic and petrogenetic studies; Pb, Sr, and Nd isotopic studies of very small samples for tracer, chronostratigraphic, and paleo-environmental applications; and Sr/Ca isotopes via isotope dilution for paleoenvironme ntal studies. Their current mass spectrometer is heavily utilized by graduate students. Approximately half of these students are women, a minority in the geosciences. The University of Florida is supporting this project with $360,730, which represents a 50% cost share. ***