Broad levels in ${}^{17}$O and their relevance for the astrophysical s-process

Abstract

Levels in ${}^{17}$O affect the astrophysical s-process in two opposite ways. The neutron production is enhanced by resonances in the ${}^{13}$C($\alpha$,$n$)${}^{16}$O reaction at excitation energies around 7 MeV in ${}^{17}$O, and the number of available neutrons is reduced by low-lying resonances in the ${}^{16}$O($n$,$\gamma$)${}^{17}$O reaction corresponding to levels in ${}^{17}$O with excitation energies of $4-5$ MeV. The present work uses the ${}^{19}$F($d$,$\alpha$)${}^{17}$O reaction to determine absolute widths of the relevant levels in ${}^{17}$O. The results improve the uncertainties of the previously adopted values and resolve a discrepancy between recent studies for the $1/2^{+}$ level close to the threshold of the ${}^{13}$C($\alpha$,$n$)${}^{16}$O reaction. In addition, improved excitation energies and widths are provided for several states in ${}^{17}$O up to excitation energies close to 8 MeV.

5 pages, 2 figures, Phys. Rev. C (in press)

References in corpus (2)

• New determination of the 13C(a, n)16O reaction rate and its influence on the s-process nucleosynthesis in AGB stars
• New $\alpha$ ANC measurement of the 1/2${}^{+}$ state in ${}^{17}$O at 6.356 MeV, that dominates the ${}^{13}$C($\alpha$,n)${}^{16}$O reaction rate at temperatures relevant for the s-process

Cited by in corpus (12)

• Probing the resonance of Dirac particle by the application of complex momentum representation
• The importance of the 13C(alpha,n)16O reaction in Asymptotic Giant Branch stars
• Concurrent application of ANC and THM to assess the ${}^{13}\mathrm{C}(\alpha ,n{)}^{16}\mathrm{O}$ absolute cross section at astrophysical energies and possible consequences for neutron production in low-mass AGB stars
• Green's function method for the single-particle resonances in a deformed Dirac equation
• Probing the resonance in the Dirac equation with quadruple-deformed potentials by complex momentum representation method
• The study of key reactions shaping the post main-sequence evolution of massive stars in underground facilities
• Re-evaluation of the ${}^{16}$O($n$,$\gamma$)${}^{17}$O cross section at astrophysical energies and its role as neutron poison in the $s$ process
• Subthreshold resonances and resonances in the $R$-matrix method for binary reactions and in the Trojan Horse method
• Connection between asymptotic normalization coefficients and resonance widths of mirror states
• Trojan horse method as surrogate indirect approach to study resonant reactions in nuclear astrophysics
• Evaluation of the ${}^{13}$N($\alpha$,p)${}^{16}$O thermonuclear reaction rate and its impact on the isotopic composition of supernova grains
• Status and future directions for direct cross-section measurements of the 13C(a,n)16O reaction for astrophysics