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Neutron spectroscopy of 26Mg states: Constraining the stellar neutron source 22Ne(α, n)25Mg

This work reports on accurate, high-resolution measurements of the 25Mg(n, γ)26Mg and 25Mg(n, tot) cross sections in the neutron energy range from thermal to about 300 keV, leading to a significantly improved 25Mg(n, γ)26Mg parametrization. The relevant resonances for n+25Mg were characterized from a combined R-matrix analysis of the experimental data. This resulted in an unambiguous spin/parity assignment of the corresponding excited states in 26Mg. With this information experimental upper limits of the reaction rates for 22Ne(α, n)25Mg and 22Ne(α, γ)26Mg were established, potentially leading to a significantly higher (α, n)/(α, γ)ratio than previously evaluated. The impact of these results has been studied for stellar models in the mass range 2 to 25 M.

s Process, α+22Ne, Neutron spectroscopy

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