Heber, Veronika S. and Wiens, Roger C. and Jurewicz, Amy J. G. and Vogel, Nadia and Reisenfeld, Daniel B. and Baur, Heinrich and McKeegan, Kevin D. and Wieler, Rainer and Burnett, Donald S. (2011) Isotopic and elemental fractionation of solar wind implanted in the Genesis concentrator target characterized and quantified by noble gases. Meteoritics and Planetary Science, 46 (4). pp. 493-512. ISSN 1086-9379. http://resolver.caltech.edu/CaltechAUTHORS:20130419-103126504
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We report concentrations and isotopic compositions of He, Ne, and Ar measured with high spatial resolution along a radial traverse of a silicon carbide (SiC) quadrant of the Genesis mission concentrator target. The Ne isotopic composition maps instrumental fractionation as a function of radial position in the target: the maximum observed isotopic fractionation is approximately 33‰ per mass unit between the center and periphery. The Ne fluence is enhanced by a factor of 43 at the target center and decreases to 5.5 times at the periphery relative to the bulk solar wind fluence. Neon isotopic profiles measured along all four arms of the "gold cross" mount which held the quadrants in the concentrator target demonstrate that the concentrator target was symmetrically irradiated during operation as designed. We used implantation experiments of Ne into SiC and gold to quantify backscatter loss and isotopic fractionation and compared measurements with numerical simulations from the code "stopping and range of ions in matter." The ^(20)Ne fluence curve as a function of radial distance on the target may be used to construct concentration factors relative to bulk solar wind for accurate corrections for solar wind fluences of other light elements to be measured in the concentrator target. The Ne isotopic composition as a function of the radial distance in the SiC quadrant provides a correction for the instrumental mass-dependent isotopic fractionation by the concentrator and can be used to correct measured solar wind oxygen and nitrogen isotopic compositions to obtain bulk solar wind isotopic compositions.
|Additional Information:||© 2011 The Meteoritical Society. Received 22 July 2010; revision accepted 12 December 2010. We thank NASA Discovery Mission Office for its support of the Genesis mission and the NASA Laboratory Analysis of Returned Samples Program Office for providing subsequent support. We greatly appreciate the support from Judith H. Allton and the entire Genesis curation team at Johnson Space Center for sample selection. We are grateful to Yong Wang and the Los Alamos Ion Beam Materials Laboratory for performing the ion implants used in this work. We are very thankful for the comments and corrections provided by the referees Andrew Davis, Bernard Marty, Sasha Verchovsky and by the Associate Editor Marc Caffee. V. S. Heber acknowledges support by the Swiss National Science Foundation and NASA Cosmochemistry.|
|Official Citation:||HEBER, V. S., WIENS, R. C., JUREWICZ, A. J. G., VOGEL, N., REISENFELD, D. B., BAUR, H., McKEEGAN, K. D., WIELER, R. and BURNETT, D. S. (2011), Isotopic and elemental fractionation of solar wind implanted in the Genesis concentrator target characterized and quantified by noble gases. Meteoritics & Planetary Science, 46: 493–512. doi: 10.1111/j.1945-5100.2011.01170.x|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||19 Apr 2013 21:19|
|Last Modified:||19 Apr 2013 21:19|
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