Spectroscopy of ${}^{19}$Ne for the thermonuclear ${}^{15}$O($\alpha ,\gamma$)${}^{19}$Ne and ${}^{18}$F($p,\alpha$)${}^{15}$O reaction rates

Abstract

Uncertainties in the thermonuclear rates of the ${}^{15}$O($\alpha ,\gamma$)${}^{19}$Ne and ${}^{18}$F($p,\alpha$)${}^{15}$O reactions affect model predictions of light curves from type I X-ray bursts and the amount of the observable radioisotope ${}^{18}$F produced in classical novae, respectively. To address these uncertainties, we have studied the nuclear structure of ${}^{19}$Ne over $E_x=4.0-5.1$ MeV and $6.1-7.3$ MeV using the ${}^{19}$F(${}^3$He,t)${}^{19}$Ne reaction. We find the $J^{\pi }$ values of the 4.14 and 4.20 MeV levels to be consistent with $9/2^{-}$ and $7/2^{-}$ respectively, in contrast to previous assumptions. We confirm the recently observed triplet of states around 6.4 MeV, and find evidence that the state at 6.29 MeV, just below the proton threshold, is either broad or a doublet. Our data also suggest that predicted but yet unobserved levels may exist near the 6.86 MeV state. Higher resolution experiments are urgently needed to further clarify the structure of ${}^{19}$Ne around the proton threshold before a reliable ${}^{18}$F($p,\alpha$)${}^{15}$O rate for nova models can be determined.

5 pages, 3 figures, Phys. Rev. C (in press)

References in corpus (7)

• Nucleosynthesis in Type I X-ray Bursts
• First application of the Trojan Horse Method with a Radioactive Ion Beam: study of the ${}^{18}$F($p,\alpha$)${}^{15}$O}} reaction at astrophysical energies
• The ${}^{15}$O($\alpha$,$\gamma$)${}^{19}$Ne Breakout Reaction and Impact on X-Ray Bursts
• Reaction Rate and Composition Dependence of the Stability of Thermonuclear Burning on Accreting Neutron Stars
• Is γ-ray emission from novae affected by interference effects in the 18F(p,α)15O reaction?
• Resonances in 19Ne with relevance to the astrophysically important 18F(p,α)15O reaction
• Isotopic 32S/33S ratio as a diagnostic of presolar grains from novae

Cited by in corpus (5)

• Key ${}^{19}$Ne states identified affecting $\gamma$-ray emission from ${}^{18}$F in novae
• Uncertainties in the ${}^{18}$F(p,$\alpha$)${}^{15}$O reaction rate in classical novae
• New $\gamma$-ray Transitions Observed in ${}^{19}$Ne with Implications for the ${}^{15}$O($\alpha$,$\gamma$)${}^{19}$Ne Reaction Rate
• Sub-threshold states in ${}^{19}$Ne relevant to ${}^{18}$F(p,$\alpha$)${}^{15}$O
• Spin-parities of sub-threshold resonances in the ${}^{18}$F(p, $\alpha$)${}^{15}$O reaction