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⊙
Massimi, C., Altstadt, S., Andrzejewski, J., Audouin, L., Barbagallo, M., Bécares, V., et al. (2017). Neutron spectroscopy of 26 Mg states: Constraining the stellar neutron source 22 Ne( α , n ) 25 Mg. PHYSICS LETTERS. SECTION B, 768, 1-6 [10.1016/j.physletb.2017.02.025].
Neutron spectroscopy of 26 Mg states: Constraining the stellar neutron source 22 Ne( α , n ) 25 Mg
MASSIMI, CRISTIAN;LO MEO, SERGIO;MINGRONE, FEDERICA;VANNINI, GIANNI;
2017
Abstract
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⊙| File | Dimensione | Formato | |
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