Refurbishment of a VG Sector Mass Spectrometer to Gain Negative Ion Capability

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EAR-0345135MukasaFunds from this award are to be used to convert an old VG Sector conventional thermal ionization mass spectrometer at the University of Michigan into a negative ion thermal ionization mass spectrometer (N-TIMS). Once modified, the instrument will be used in geological and environmental studies that require the measurement of isotopic ratios for osmium and boron in their electronegative form. We anticipate collaborations with both internal and external colleagues, which will keep the facility very busy. The mass spectrometer to be converted has the "Multi-1" collector block with six old-design, short-life, Faraday cups that are moved manually. Because of their advanced age and throughput, the Faraday detectors have suffered some damage leading to degradation in gain and peak shape. The net result of this wear and tear is poor precision and reproducibility in the measurements of Sr and Nd isotopic ratios. However, because osmium and boron isotopic ratios have very large variations in nature, their measurements do not require the high precision necessary for Sr and Nd isotopes. Therefore, refurbishing the electronic components of the instrument along with converting it to negative ion capability - but not replacing the collectors - will extend the machine's life and afford us the opportunity to do research in new areas of the geological and environmental sciences. This N-TIMS conversion will open our respective groups to new areas of research that use electronegative ions, such as Os and B, and provide our students and postdoctoral research fellows with a "new tool" for tackling their research projects in high-temperature geochemistry, petrology, environmental geochemistry economic geology, and paleooceanography. Just as importantly, the refurbished instrument will be used to teach students some fundamental skills such as mass spectrometry, formulation of research problems, objective data processing and analysis, and the presentation of written and oral reports. These skills can be applied to later work situations in academia, government, or industry.