Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis

Abstract

The distribution of solar-wind ions in Genesis mission collectors, as determined by depth profiling analysis, constrains the physics of ion-solid interactions involving the solar wind. Thus, they provide an experimental basis for revealing ancient solar activities represented by solar-wind implants in natural samples. We measured the first depth profile of ^4He in a Genesis collector; the shallow implantation (peaking at <20 nm) required us to use sputtered neutral mass spectrometry with post-photoionization by a strong field. The solar wind He fluence calculated using depth profiling is ~8.5 × 10^(14) cm^(–2). The shape of the solar wind 4He depth profile is consistent with TRIM simulations using the observed ^4He velocity distribution during the Genesis mission. It is therefore likely that all solar-wind elements heavier than H are completely intact in this Genesis collector and, consequently, the solar particle energy distributions for each element can be calculated from their depth profiles. Ancient solar activities and space weathering of solar system objects could be quantitatively reproduced by solar particle implantation profiles.

Additional Information

© 2015 by The Geochemical Society of Japan. Received January 23, 2015; Accepted June 30, 2015. We thank Hajime Hiyagon and an anonymous reviewer for their constructive reviews and suggestions and Yuji Sano for his kind editorial advice. This study is supported in part by Monka-sho grants. This is a contribution to Los Alamos publication LA-UR-15-21508.

Attached Files

Supplemental Material - MS385.pdf

Files

Additional details