Mg cross section*

The ²²Ne(α,n)²⁵Mg reaction is one of the most important neutron sources for s-process nucleosynthesis, which is responsible for the production of ~50% of the elements heavier than Fe in the Solar System. A recent experimental study (S. Ota et al. 2020) indicated that the cross section at stellar temperatures might be smaller than the conventional ones, leading to ~4 times lower stellar reaction rates. We probed the impact of the new ²²Ne(α,n)²⁵Mg reaction rates on the chemical abundances in massive stars and core-collapse supernovae. We simulated the nucleosynthesis of stars with different initial masses (12 - 25 M☉) and metallicities (0.0001-0.02) using the conventional and new rates with NuGrid’s multi-zone post-processing nucleosynthesis code, MPPNP. The stellar yields from MPPNP are fed into the galactic chemical evolution (GCE) code OMEGA+. The galactic abundances of s-process isotopes are reduced by up to 65% when comparing the new and conventional rates. The ratio of ⁶⁰Fe to ²⁶Al , s-process radioactive isotopes, using the new cross section reproduces the observed ratio by the INTEGRAL satellite within the uncertainties. Overall, accurate ²²Ne(α,n)²⁵Mg cross sections can have a significant impact on GCE to reproduce the astronomical observational data.