We compare updated Torino postprocessing asymptotic giant branch (AGB) nucleosynthesis model calculations with isotopic compositions of mainstream SiC dust grains from low-mass AGB stars. Based on the data-model comparison, we provide new constraints on the major neutron source, 13C({\alpha},n)16O in the He-intershell, for the s-process. We show that the literature Ni, Sr, and Ba grain data can only be consistently explained by the Torino model calculations that adopt the recently proposed magnetic-buoyancy-induced 13C-pocket. This observation provides strong support to the suggestion of deep mixing of H into the He-intershell at low 13C concentrations as a result of efficient transport of H through magnetic tubes.
@article{arxiv.1808.03614,
title = {New constraints on the major neutron source in low-mass AGB stars},
author = {Nan Liu and Roberto Gallino and Sergio Cristallo and Sara Bisterzo and Andrew M. Davis and Reto Trappitsch and Larry R. Nittler},
journal= {arXiv preprint arXiv:1808.03614},
year = {2018}
}