Spallation recoil and age of presolar grains in meteorites

Details Spallation recoil and age of presolar grains in meteorites Spallation recoil and age of presolar grains in meteorites

Jan 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000m%26ps...35...53o&link_type=abstract

Meteoritics & Planetary Science, vol. 35, no. 1, pp. 53-63 (2000).

Computer Science

14

Scientific paper

We have determined the recoil losses from silicon carbide grain size fractions of spallation neon produced by irradiation with 1.6 GeV protons. During the irradiation the SiC grains were dispersed in paraffin wax in order to avoid re-implantation into neighboring grains. Analysis for spallogenic 21Ne of grain size separates in the size range 0.3 μm to 6 μm and comparison with the 22Na activity of the SiC+paraffin mixture indicates an effective recoil range of 2-3 μm with no apparent effect from acid treatments such as routinely used in the isolation of meteoritic SiC grains. Our results indicate that the majority of presolar SiC grains in primitive meteorites, which are ~μm-sized, will have lost essentially all spallogenic Ne produced by cosmic ray interaction in the interstellar medium. This argues against the validity of previously published presolar ages of Murchison SiC (~10 to ~130 Ma; increasing with grain size; Lewis et al., 1994), where recoil losses had been based on calculated recoil energies. It is argued that the observed variations in meteoritic SiC grain size fractions of 21Ne/22Ne ratios are more likely due to the effects of nucleosynthesis in the He burning shell of the parent AGB stars which imposes new boundary conditions on nuclear parameters and stellar models. It is suggested that spallation-Xe produced on the abundant Ba and REE in presolar SiC, rather than spallogenic Ne, may be a promising approach to the presolar age problem. There is a hint in the currently available Xe data (Lewis et al., 1994) that the large (>1 μm) grains may be younger than the smaller (<1 μm) ones.

Affiliated with

Also associated with

No associations

Rating

Spallation recoil and age of presolar grains in meteorites does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Spallation recoil and age of presolar grains in meteorites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spallation recoil and age of presolar grains in meteorites will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-807995