Neutron capture reaction rates for silicon and their impact on the origin of presolar mainstream SiC grains

Guber, K. H. and Koehler, P. E. and Derrien, H. and Valentine, T. E. and Leal, L. C. and Sayer, R. O. and Rauscher, T.. (2003) Neutron capture reaction rates for silicon and their impact on the origin of presolar mainstream SiC grains. Physical review. C, Nuclear physics, Vol. 67, H. 6 , 062802.

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Official URL: http://edoc.unibas.ch/dok/A5839271

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We have made new, improved measurements of the Si28-30 (n, gamma) cross sections and have done a resonance analysis of these data including previous total cross sections. Together with the calculated contributions due to direct capture, we calculated the astrophysical (n, gamma) reaction rates and investigated the s-process abundances of the Si isotopes. Measured isotopic anomalies of intermediate and heavy elements in SiC grains from meteorites appear to be attributable to the s-process in asymptotic giant branch (AGB) stars. But the Si isotopic ratios in these grains are substantially different than s-process models predict. Therefore, recent papers have invoked galactic chemical evolution or other effects to explain the Si isotope ratios in these grains. Our new reaction rates are significantly different than previous rates, and s-process calculations using these rates lead to much larger isotopic shifts in Si-30. However, these exploratory calculations demonstrate that even with these substantially different rates the large observed variation in SiC grain from AGB stars cannot be explained by standard s-process models.
Faculties and Departments:05 Faculty of Science > Departement Physik > Former Organization Units Physics > Theoretische Physik Astrophysik (Thielemann)
UniBasel Contributors:Rauscher, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Institute of Physics
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Sep 2012 07:18
Deposited On:14 Sep 2012 06:45

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