Adsley, P., Hammache, F., Séréville, N. de et al. (30 more authors) (2020) Charged-particle branching ratios above the neutron threshold in $^{19}$F:constraining $^{15}$N production in core-collapse supernovae. Phys. Rev. C. ISSN 2469-9993
Abstract
Spatially-correlated overabundances of $^{15}$N and $^{18}$O observed in some low-density graphite meteoritic grains have been connected to nucleosynthesis taking place in the helium-burning shell during core-collapse supernovae. Two of the reactions which have been identified as important to the final abundances of $^{15}$N and $^{18}$O are $^{18}$F($n,\alpha$)$^{15}$N and $^{18}$F($n,p$)$^{18}$O. The relative strengths of the $^{18}$F($n,\alpha$)$^{15}$N and $^{18}$F($n,p$)$^{18}$O reactions depend on the relative $\alpha_0$ and $p_0$ decays from states above the neutron threshold in $^{19}$F in addition to other properties. Experimental data on the charged-particle decays from these highly excited states are lacking or inconsistent. Two experiments were performed using proton inelastic scattering from LiF targets and magnetic spectrographs. The first experiment used the high-resolution Q3D spectrograph at Munich to constrain properties of levels in $^{19}$F. A second experiment using the Orsay Split-Pole spectrograph and an array of silicon detectors was performed in order to measure the charged-particle decays of neutron-unbound levels in $^{19}$F. A number of levels in $^{19}$F have been identified along with their corresponding charged-particle decays. The first state above the neutron threshold which has an observed proton-decay branch to the ground state of $^{18}$O lies 68 keV above the neutron threshold while the $\alpha$-particle decays from the neutron-unbound levels are generally observed to be much stronger than the proton decays. Neutron-unbound levels in $^{19}$F are observed to decay predominantly by $\alpha$-particle emission, supporting the role of $^{18}$F($n,\alpha$)$^{15}$N in the production of $^{15}$N in the helium-burning shell of supernovae. Improved resonant-scattering reaction data are required in order to be able to determine the reaction rates accurately.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | ©2021 American Physical Society 13 pages, 5 figures, v3 more wrong affiliations |
Keywords: | nucl-ex,astro-ph.SR |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL (STFC) ST/P003885/1 |
Depositing User: | Pure (York) |
Date Deposited: | 29 Mar 2021 09:50 |
Last Modified: | 16 Oct 2024 17:27 |
Published Version: | https://doi.org/10.1103/PhysRevC.103.035804 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1103/PhysRevC.103.035804 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:172626 |