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Experimental Determination of α Widths of ^{21}Ne Levels in the Region of Astrophysical Interest: New ^{17}O+α Reaction Rates and Impact on the Weak s Process.

Hammache, F; Adsley, P; Lamia, L; Harrouz, D S; de Séréville, N; Bastin, B; Choplin, A; Faestermann, T; Fougères, C; Hertenberger, R; Hirschi, R; La Cognata, M; Meyer, A; Palmerini, S; Pizzone, R G; de Oliveira Santos, F; Romano, S; Tumino, A; Wirth, H-F

Authors

F Hammache

P Adsley

L Lamia

D S Harrouz

N de Séréville

B Bastin

A Choplin

T Faestermann

C Fougères

R Hertenberger

M La Cognata

A Meyer

S Palmerini

R G Pizzone

F de Oliveira Santos

S Romano

A Tumino

H-F Wirth



Abstract

The efficiency of the weak s process in low-metallicity rotating massive stars depends strongly on the rates of the competing ^{17}O(α,n)^{20}Ne and ^{17}O(α,γ)^{21}Ne reactions that determine the potency of the ^{16}O neutron poison. Their reaction rates are poorly known in the astrophysical energy range of interest for core helium burning in massive stars because of the lack of spectroscopic information (partial widths, spin parities) for the relevant states in the compound nucleus ^{21}Ne. In this Letter, we report on the first experimental determination of the α-particle spectroscopic factors and partial widths of these states using the ^{17}O(^{7}Li,t)^{21}Ne α-transfer reaction. With these the ^{17}O(α,n)^{20}Ne and ^{17}O(α,γ)^{21}Ne reaction rates were evaluated with uncertainties reduced by a factor more than 3 with respect to previous evaluations and the present ^{17}O(α,n)^{20}Ne reaction rate is more than 20 times larger. The present (α,n)/(α,γ) rate ratio favors neutron recycling and suggests an enhancement of the weak s process in the Zr-Nd region by more than 1.5 dex in metal-poor rotating massive stars.

Citation

Hammache, F., Adsley, P., Lamia, L., Harrouz, D. S., de Séréville, N., Bastin, B., …Wirth, H.-F. (2024). Experimental Determination of α Widths of ^{21}Ne Levels in the Region of Astrophysical Interest: New ^{17}O+α Reaction Rates and Impact on the Weak s Process. Physical Review Letters, 132(18), Article 182701. https://doi.org/10.1103/PhysRevLett.132.182701

Journal Article Type Article
Acceptance Date Mar 26, 2024
Online Publication Date May 1, 2024
Publication Date May 3, 2024
Deposit Date Jun 25, 2024
Journal Physical review letters
Print ISSN 0031-9007
Electronic ISSN 1079-7114
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 132
Issue 18
Article Number 182701
DOI https://doi.org/10.1103/PhysRevLett.132.182701
Public URL https://keele-repository.worktribe.com/output/844776
Publisher URL https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.182701