Key ${}^{19}$Ne states identified affecting $\gamma$-ray emission from ${}^{18}$F in novae

Abstract

Detection of nuclear-decay $\gamma$ rays provides a sensitive thermometer of nova nucleosynthesis. The most intense $\gamma$-ray flux is thought to be annihilation radiation from the ${\beta }^{+}$ decay of ${}^{18}$F, which is destroyed prior to decay by the ${}^{18}$F($p$,$\alpha$)${}^{15}$O reaction. Estimates of ${}^{18}$F production had been uncertain, however, because key near-threshold levels in the compound nucleus, ${}^{19}$Ne, had yet to be identified. This Letter reports the first measurement of the ${}^{19}$F(${}^3$He,$t\gamma$)${}^{19}$Ne reaction, in which the placement of two long-sought 3/2${}^{+}$ levels is suggested via triton-$\gamma$-$\gamma$ coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of $1.5-17$ at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.

arXiv comment6 pages, 4 figures

References in corpus (8)

• Science with e-ASTROGAM (A space mission for MeV-GeV gamma-ray astrophysics)
• The Galactic Nova Rate Revisited
• New Constraints on the 18F(p,alpha) 15O Rate in Novae from the (d,p) Reaction
• Is γ-ray emission from novae affected by interference effects in the 18F(p,α)15O reaction?
• Gamma-Ray Observations of Nova Sgr 2015 No. 2 with INTEGRAL
• The 18F(p,a)15O reaction rate for application to nova gamma-ray emission
• Spectroscopy of ${}^{19}$Ne for the thermonuclear ${}^{15}$O($\alpha ,\gamma$)${}^{19}$Ne and ${}^{18}$F($p,\alpha$)${}^{15}$O reaction rates
• Indirect study of 19Ne states near the 18F+p threshold

Cited by in corpus (3)

• Uncertainties in the ${}^{18}$F(p,$\alpha$)${}^{15}$O reaction rate in classical novae
• 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