Properties of states in \textsuperscript{19}Ne important for the \textsuperscript{18}F$(p,\alpha)$\textsuperscript{15}O reaction rate

TL;DR

This study refines the understanding of nuclear states in Ne that influence the F(p,\u03b1)O reaction rate, crucial for interpreting positron signals from novae.

Contribution

It identifies key resonances in Ne and improves the accuracy of the reaction rate estimates by addressing previous underestimations of uncertainties.

Findings

Identified six near-threshold proton s-wave states in Ne.

Studied asymptotic normalization using the no-core shell model.

Revealed that earlier studies underestimated uncertainties in the reaction rate.

Abstract

Observation of the 511-keV positron-annihilation line would be a powerful probe of classical novae, with the primary source of positrons likely from the $\beta^+$ decay of \textsuperscript{18}F. We have determined the properties of important resonances in $^{19}$Ne which govern the \textsuperscript{18}F($p,\alpha$)\textsuperscript{15}O reaction rate and the production of \textsuperscript{18}F in novae. Measured $\alpha$ and proton angular distributions from states populated in the \textsuperscript{19}F(\textsuperscript{3}He,$t$)\textsuperscript{19}Ne reaction identified six near-threshold proton $s$-wave \textsuperscript{18}F$+p$ ($L_p=0$) states, and the asymptotic normalization of these states was studied using the symmetry-adapted no-core shell model. We have improved our understanding of states contributing to the \textsuperscript{18}F($p,\alpha$)\textsuperscript{15}O reaction rate and show that earlier studies significantly underestimated the uncertainties.