title: Constraints on neon and argon isotopic fractionation in solar wind.
abstract: To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in 20Ne/22Ne or 36Ar/38Ar values. For 20Ne/22Ne, the difference between low- and high-speed wind components is 0.24 +/- 0.37%; for 36Ar/38Ar, it is 0.11 +/- 0.26%. Our measured 36Ar/38Ar ratio in the solar wind of 5.501 +/- 0.005 is 3.42 +/- 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history.
authors.affiliation: Physics Department, Washington University, St. Louis, MO 63130, USA. am@physics.wustl.edu
authors.forename: Alex
authors.initials: A
authors.lastname: Meshik
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mabry
authors.forename: Charles
authors.initials: C
authors.lastname: Hohenberg
authors.forename: Yves
authors.initials: Y
authors.lastname: Marrocchi
authors.forename: Olga
authors.initials: O
authors.lastname: Pravdivtseva
authors.forename: Donald
authors.initials: D
authors.lastname: Burnett
authors.forename: Chad
authors.initials: C
authors.lastname: Olinger
authors.forename: Roger
authors.initials: R
authors.lastname: Wiens
authors.forename: Dan
authors.initials: D
authors.lastname: Reisenfeld
authors.forename: Judith
authors.initials: J
authors.lastname: Allton
authors.forename: Karen
authors.initials: K
authors.lastname: McNamara
authors.forename: Eileen
authors.initials: E
authors.lastname: Stansbery
authors.forename: Amy J G
authors.initials: AJ
authors.lastname: Jurewicz