Improved direct measurement of low-energy resonances in the $^{21}$Ne(p,$\gamma$)$^{22}$Na reaction

TL;DR

This study provides high-precision measurements of low-energy resonances in the $^{21}$Ne(p,$ extgamma$)$^{22}$Na reaction, reducing uncertainties in astrophysical models of nova nucleosynthesis.

Contribution

It offers new resonance strength measurements and decay schemes, leading to an updated reaction rate for better astrophysical modeling.

Findings

Resonance strengths for 272.3 and 352.6 keV are significantly higher than previous data.

New branching ratios were determined for key resonances.

Revised reaction rate impacts NeNa nucleosynthesis predictions.

Abstract

In the nova temperature range, 0.1 GK $< T <$ 0.4 GK, several low-energy resonances dominate the $^{21}$Ne(p,$\gamma$)$^{22}$Na reaction rate, which is currently affected by large uncertainties. We present a high-precision study of the resonances at $E^{\rm{lab}}_{\rm{r}}$ = 127.3, 271.4, 272.3, 291.5, and 352.6 keV, measured directly at the Laboratory for Underground Nuclear Astrophysics in Italy. The strengths of the 127.3, 271.4, and 291.5 keV resonances are consistent with previous measurements within 1$\sigma$. However, for the 272.3 keV and 352.6 keV resonances, we report strength values of (129.9 $\pm$ 5.8) meV and (14.9 $\pm$ 0.8) meV, respectively, more than a factor of 1.5 higher than literature values. In addition, we report on new branching ratios for the 127.3, 272.3, and 352.6 keV resonances, leading to updated decay schemes. Finally, we present a revised thermonuclear reaction rate and investigate its impact on the NeNa nucleosynthesis.