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Decay properties of 22Ne + � resonances and their impact on s-process nucleosynthesis

Ota, S., Christian, G., Lotay, G., Catford, W.N, Bennett, E.A, Dede, S., Doherty, Daniel, Hallam, Sam, Hooker, J., Hunt, C. , Jayatissa, H., Matta, A., Moukaddam, Mohamad, Rogachev, G.V, Saastamoinen, A., Tostevin, Jeffrey, Upadhyayula, S. and Wilkinson, Ryan (2020) Decay properties of 22Ne + � resonances and their impact on s-process nucleosynthesis Physics Letters B, 802, 135256.

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The astrophysical s-process is one of the two main processes forming elements heavier than iron. A key outstanding uncertainty surrounding s-process nucleosynthesis is the neutron flux generated by the 22Ne(�; n)25Mg reaction during the He-core and C-shell burning phases of massive stars. This reaction, as well as the competing 22Ne(�;)26Mg reaction, is not well constrained in the important temperature regime from �0:2–0:4 GK, owing to uncertainties in the nuclear properties of resonances lying within the Gamow window. To address these uncertainties, we have performed a new measurement of the 22Ne(6Li; d)26Mg reaction in inverse kinematics, detecting the outgoing deuterons and 25;26Mg recoils in coincidence. We have established a new n= decay branching ratio of 1:14(26) for the key Ex = 11:32 MeV resonance in 26Mg, which results in a new (�; n) strength for this resonance of 42(11) �eV when combined with the well-established (�; ) strength of this resonance. We have also determined new upper limits on the � partial widths of neutron-unbound resonances at Ex = 11:112; 11:163, 11:169, and 11:171 MeV. Monte-Carlo calculations of the stellar 22Ne(�; n)25Mg and 22Ne(�; )26Mg rates, which incorporate these results, indicate that both rates are substantially lower than previously thought in the temperature range from �0:2–0:4 GK.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Ota, S.
Christian, G.
Lotay, G.
Catford, W.N
Bennett, E.A
Dede, S.
Hooker, J.
Hunt, C.
Jayatissa, H.
Matta, A.
Rogachev, G.V
Saastamoinen, A.
Upadhyayula, S.
Date : 22 January 2020
Funders : Science and Technology Facilities Council (STFC)
DOI : doi.10.1016/j.physletb.2020.135256
OA Location :
Grant Title : Science and Technology Facilities Council Grant
Depositing User : James Marshall
Date Deposited : 30 Jan 2020 16:43
Last Modified : 10 Feb 2020 11:25

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