First inverse kinematics measurement of key resonances in the ${}^{22}\text{Ne}(p,\gamma)^{23}\text{Na}$ reaction at stellar temperatures

TL;DR

This study presents the first inverse kinematics measurement of key resonances in the ${}^{22} ext{Ne}(p, ext{ extgamma})^{23} ext{Na}$ reaction, crucial for understanding sodium production in stars, with improved precision on resonance strengths impacting stellar nucleosynthesis models.

Contribution

It provides the first independent and more precise measurement of the ${}^{22} ext{Ne}(p, ext{ extgamma})^{23} ext{Na}$ reaction resonance at 458 keV, addressing nuclear physics uncertainties in stellar evolution models.

Findings

Measured resonance strengths at four key energies.

Found the 458 keV resonance strength with higher precision.

Deviated from recent normal kinematics measurements, aligning with earlier data.

Abstract

In this Letter we report on the first inverse kinematics measurement of key resonances in the ${}^{22}\text{Ne}(p,\gamma)^{23}\text{Na}$ reaction which forms part of the NeNa cycle, and is relevant for ${}^{23}$Na synthesis in asymptotic giant branch (AGB) stars. An anti-correlation in O and Na abundances is seen across all well-studied globular clusters (GC), however, reaction-rate uncertainties limit the precision as to which stellar evolution models can reproduce the observed isotopic abundance patterns. Given the importance of GC observations in testing stellar evolution models and their dependence on NeNa reaction rates, it is critical that the nuclear physics uncertainties on the origin of ${}^{23}$Na be addressed. We present results of direct strengths measurements of four key resonances in ${}^{22}\text{Ne}(p,\gamma)^{23}\text{Na}$ at E$_{{\text c.m.}}$ = 149 keV, 181 keV, 248 keV and 458 keV. The strength of the important E$_{{\text c.m.}}$ = 458 keV reference resonance has been determined independently of other resonance strengths for the first time with an associated strength of $\omega\gamma$ = 0.439(22) eV and with higher precision than previously reported. Our result deviates from the two most recently published results obtained from normal kinematics measurements performed by the LENA and LUNA collaborations but is in agreement with earlier measurements. The impact of our rate on the Na-pocket formation in AGB stars and its relation to the O-Na anti-correlation was assessed via network calculations. Further, the effect on isotopic abundances in CO and ONe novae ejecta with respect to pre-solar grains was investigated.