Research on concentrations and isotopic abundances of retractory siderophile elements in Ca, Al-rich inclusions and estimation of chemical and physical conditions of the primitive solar nebula

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In order to estimate chemical and physical conditions of the primitive solar nebula, Ca, Al-rich inclusions in the Allende CV3 chondrite were investigated. Methods for quantitative analysis and isotopic ratio measurement of refractory siderophile elements were developed and a search for extinct nuclides was performed.Three Ca, Al-rich inclusions including a lcm-radius spherule were separated from three specimens of the Allende meteorite in the collection of the, National Science Museum A11 of them are coarse-grained inclusions and, from observation using SEM-EDX, one is classified as a Type A inclusion with melilite and spinel ; another inclusion is probably a Type C because of high abundance of anorthite ; the other could be a Type B Using a SIMS at Hiroshima University, Mg-26 excesses due to the extinct nuclideAl-26 were observed in anorthite of the Type C inclusion Also, a trace of the extinct nuclide Cs-135 was detected in an acid-soluble fraction in an H chondriteMethods for quantitative analysis of refractory siderophile elements using an ICP-MS were explored in addition to the well-developed NAA methods. Change of sensitivities of the refractory siderophile elements had to be monitored and severe memory, effects were observed at the measurements of Os. For the negative thermal ionization mass spectrometry of the platinum group elements and other siderophile elements, basic behaviors of formation of negative thermal ions from a mixed solution were investigated in collaboration with Prof. K CJ. Heumann at the University of Mainz Using a Pt single filament method, the intensities of negative thermal ions from the same amount of elements were Re > Os > Ir -- Ru > Mo The Re filament method could be used for better ionization of W and Mo.