HR: 12:05h
AN: SH32A-08    [Abstracts]
TI: Solar Wind Neon Isotopic Analyses by UV Laser Ablation on the Genesis Concentrator Gold Cross for Calibration of Oxygen Isotope Data
AU: * Heber, V S
EM: heber@erdw.ethz.ch
AF: Isotope Geology ETH Zurich, Sonneggstrasse, Zurich, 8092 Switzerland
AU: Wiens, R C
EM: rwiens@lanl.gov
AF: Los Alamos National Laboratory, Space and Atmospheric Sciences, MS-D466, Los Alamos, NM 87545 United States
AU: Burnett, D S
EM: burnett@gps.caltech.edu
AF: Caltech, Division of Geological and Planetary Sciences, MS 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Baur, H
EM: baur@erdw
AF: Isotope Geology ETH Zurich, Sonneggstrasse, Zurich, 8092 Switzerland
AU: Wiechert, U H
EM: Wiechert@erdw.ethz.ch
AF: Isotope Geology ETH Zurich, Sonneggstrasse, Zurich, 8092 Switzerland
AU: Wieler, R
EM: wieler@erdw.ethz.ch
AF: Isotope Geology ETH Zurich, Sonneggstrasse, Zurich, 8092 Switzerland
AB: To determine the oxygen isotopic composition of the present day solar wind, a proxy for the solar nebula, is one of the key goals of the Genesis solar wind (SW) collection mission. In order to increase analytical precision on measured O isotopes, ions of incoming SW in the mass range to 28 amu were accelerated and focussed onto the target by an electrostatic mirror. The concentration factor is about 20. However, these processes are expected to fractionate the isotopic composition of SW ions, with fractionation varying as a function of target radius. We will directly measure the instrumental fractionation factors by analysing Ne isotopes with high precision and spatial resolution along the radius on the electroplated Au cross that framed the concentrator targets. Ne isotopes are most suitable to investigate fractionation because of i) it is an abundant element in the Sun, ii) its isotopic composition in SW is well understood, and iii) Ne is hardly influenced by terrestrial contamination. We will analyse Ne isotopes by UV laser ablation (248 nm) of small areas (0.1 x 0.1 mm) using a very sensitive noble gas mass spectrometer equipped with a molecular drag pump conveying the gas almost quantitatively into the ion source. The target precision of O isotopic composition is about 0.1% (2-sigma). Therefore, the most important issue for us is to achieve a similar high precision of the Ne isotope data allowing to determine the trend of instrumental fractionation along the target radius, which is computed to be in total about 2%. Currently, we obtain a reproducibility of <0.2% using standard calibration gas containing similar Ne amounts as expected. Blank analyses of the ultra-clean electroplated Au target result in absolutely negligible amounts of Ne. At the meeting we will present first Ne results of the first arm analysed of the Au cross.
DE: 7599 General or miscellaneous
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005