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Elemental Comparison Between Sutter’s Mill and Murchison
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Elemental Comparison Between Sutter’s Mill and Murchison

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  1. Elemental Comparison Between Sutter’s Mill and Murchison T.A. Cahill1, S.R. Barberie1, Q.Z. Yin2 1 Department of Physics, DELTA Group, and 2 Department of Earth and Planetary Sciences, University of California Davis Abstract S-XRF comparison using X-ray counts: Sutter’s Mill 51 versus a Murchison fragment Comparison of analytical methods used for the Sutter’s Mill meteorite analyses We have used Synchrotron-Induced X-Ray Fluorescence (S-XRF) to make a model-independent comparison of a Murchison fragment (MUR) to the Sutter’s Mill meteorite fragment 51 (SM51). Our SM51 and MUR S-XRF x-ray spectra were examined for elements from silicon to barium, and then tantalum through uranium. Of the 52 elements examined, 33 had statistically sound results. For these major and trace elements, the ratios of the samples from the two meteorites were statistically equivalent, with SM51/MUR = 1.05 ± 0.06. Introduction In April, 2012, the University of California Davis (UC Davis) participated in a consortium study to analyze a meteorite fragment Sutter’s Mill 51 (SM51)1. A fragment of the Murchison meteorite2 was provided for comparison and quality assurance goals. They were both analyzed by S-XRF3 using 38 keV mono-energetic polarized x-rays of our x-ray 0.5 mm milli-probe at beam line 2-2 of the Stanford Synchrotron Radiation Lightsource (SSRL), SLAC NAL. This method is fully non-destructive, requiring no sample preparation beyond cleaning, is fast (a few hours for all 11 SM51/Murchison analyses), and can handle samples of large size. The same Sutter’s Mill fragment was also analyzed by standard XRF at Lawrence Livermore NL (LLNL) and by High Resolution Inductively Couple Plasma-Mass Spectrometry (HR ICP-MS) at UC Davis. Excellent agreement was shown for all three methods for the Sutter’s Mill analyses. The results for the SM/Mur ratio, 1.05 ± 0.06, can be compared with the literature values for SM/CM, 1.044 ± 0.095, SM/CI, 1.024 ± 0.34, and SM/Tagish, 0.97 ± 0.22.2 The uncertainty is the IUPAP definition for statistical significance. Note that the S-XRF argon values in air validate the QA precision. . Extracted from Science 2012, Table 4, Suppl. Materials 1 References [1] Jenniskens et al., Science338, 1583 (2012) [2] P. G. Brown et al., Science290, 320 (2000) [3] S.R. Barberie et al. Nucl. Instr. Meth. Phys. A: 729, 930 (2013).