Chemical composition of Yamato (Y) 000593 and Yamato 000749: Neutron-induced prompt gamma-ray analysis study

Neutron-induced prompt gamma-ray analysis (PGA) was applied to Antarctic nakhlites, Yamato (Y) 000593 and Y000749 together with Nakhla for the non-destructive determination of most major and minor elements (plus some trace elements). In addition to analyses of lump samples of these three meteorite, powder samples representing six different portions within Y000593 also were analyzed for discussing the chemical heterogeneity. As a result, it was confirmed that most major elements are homogeneously distributed among Y000593 within an error of ±10%. Chemical compositions of Y000593 and Y000749 are essentially identical within error limits, supporting the suggestion that these meteorites are paired. Compositional similarity is also confirmed between Nakhla and Y000593 (and Y000749), verifying that Y000593 (and Y000749) belong to nakhlites. Based on our PGA data coupled with literature data for Martian meteorites, we propose a diagram used for classifying achondrites and further for grouping into individual groups of Martian meteorites. Although there are some scatterings in B and Cl data, we would propose their abundances in nakhlites to be 3.33 ppm and 80 ppm, respectively. Our H data are systematically higher than their literature data. Although further refinements in our analytical procedure of PGA are required for getting more reliable and accurate values of H in Martian meteorites, it is suspected that some literature values of H contents in Martian meteorites are a little too small

Boron and chlorine abundances in Antarctic chondrites: A PGA study

Boron and chlorine abundances were determined by prompt gamma-ray analysis for Antarctic meteorites of 22 carbonaceous chondrites and 12 ordinary chondrites. Both B and Cl contents of most Antarctic meteorites analyzed in this study are systematically higher than those for non-Antarctic chondrites of corresponding groups, implying that Antarctic meteorites of carbonaceous and ordinary chondrite groups were contaminated with not only Cl (and other halogens like I) but also B. Boron and Cl contents are correlated with each other in Antarctic ordinary chondrites whereas no apparent correlation can be seen for carbonaceous chondrites. Considering that interior portions were used for carbonaceous chondrites while interior and outer portions were randomly sampled for ordinary chondrite used in this study, B and Cl are distributed differently between the two groups of chondrite, suggesting that B and Cl independently behaved following their own chemical properties after contaminant(s) carrying these elements adhered on the surface of meteorites. Sea mist is a probable candidate for such a contaminant. Leaching experiments showed that no B is essentially recovered by water and acetone even from pulverized specimens, from which a fairly large fraction of Cl is recovered, confirming that B and Cl reside independently in chondrite samples and further that both elements behaved differently after sticking to these samples on Antarctica

Complementary analysis of trace elements in nail samples using instrumental neutron activation analysis and inductively coupled plasma mass spectrometry

Instrumental neutron activation analysis (INAA) and inductively coupled plasma-mass spectrometry (ICPMS) were applied to determine minor and trace elements in human nail samples. Validation of each method was performed by measuring NIES No. 5 Human Hair certiˆed reference material. Good agreements were observed between certiˆed and measured values for these methods. Nail samples collected from 18 healthy volunteers were washed, dried and cut into small pieces. The samples were divided into two portions, one of which was analyzed by INAA and the other by ICPMS. In INAA, Na, Mg, Al, Cl, K, Ca, V, Mn and Cu were recognized and the concentrations of these elements were calculated. On the other hand, peaks of Cu, Zn, Sr,Ag, Sn, Sb, Ba,CeHg and Pb were observed in the spectrum by ICPMS. Copper, Zn, Sr, Ag and Pb were determined by ICPMS because these elements showed su‹ciently high intensity without spectrum interference. Nine and ˆve elements were determined by INAA and ICPMS. Copper was determined by both methods, and good correlation was observed. Combination of INAA and ICPMS has an advantage to provide more information of elemental contents for nail samples if more than only one of the two methods is employed

The nuclear interaction at Oklo 2 billion years ago

We re-examine the effort to constrain the time-variability of the coupling constants of the fundamental interactions by studying the anomalous isotopic abundance of Sm observed at the remnants of the natural reactors which were in operation at Oklo about 2 billion years ago, in terms of a possible deviation of the resonance energy from the value observed today. We rely on new samples that were carefully collected to minimize natural contamination and also on a careful temperature estimate of the reactors. We obtain the upper bound $(-0.2\pm 0.8)\times 10^{-17}$ ${\rm y}^{-1}$ on the fractional rate of change of the electromagnetic as well as the strong interaction coupling constants. Our result basically agrees with and even suggests some improvement of the result due recently to Damour and Dyson. Strictly speaking, however, we find another range of the resonance energy shift indicating a nonzero time variation of the constants. We find a rather strong but still tentative indication that this range can be ruled out by including the Gd data, for which it is essential to take the effect of contamination into account.Comment: 20 pages LaTex including 6 figures. Theoretical interpretation changed. More detailed discussions on the temperature estimate also adde