Re-evaluation of the \(^{22}\)Ne(\(\alpha,\gamma\))\(^{26}\)Mg and \(^{22}\)Ne(\(\alpha,n\))\(^{25}\)Mg reaction rates

The competing \(^{22}\)Ne(\(\alpha,\gamma\))\(^{26}\)Mg and \(^{22}\)Ne(\(\alpha,n\))\(^{25}\)Mg reactions control the production of neutrons for the weak \(s\)-process in massive and AGB stars. In both systems, the ratio between the corresponding reaction rates strongly impacts the total neutron budget and strongly influences the final nucleosynthesis. The \(^{22}\)Ne(\(\alpha,\gamma\))\(^{26}\)Mg and \(^{22}\)Ne(\(\alpha,n\))\(^{25}\)Mg reaction rates was re-evaluated by using newly available information on \(^{26}\)Mg given by various recent experimental studies. Evaluations of The evaluated \(^{22}\)Ne(\(\alpha,\gamma\))\(^{26}\)Mg reaction rate remains substantially similar to that of Longland {\it et al.} but, including recent results from Texas A\&M, the \(^{22}\)Ne(\(\alpha,n\))\(^{25}\)Mg reaction rate is lower at a range of astrophysically important temperatures. Stellar models computed with NEWTON and MESA predict decreased production of the weak branch \(s\)-process due to the decreased efficiency of \(^{22}\)Ne as a neutron source. Using the new reaction rates in the MESA model results in \(^{96}\)Zr/\(^{94}\)Zr and \(^{135}\)Ba/\(^{136}\)Ba ratios in much better agreement with the measured ratios from presolar SiC grains.