Direct measurement of the low energy resonances in $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction

TL;DR

This study precisely measured the low energy resonances in the $^{22}$Ne($ m{ extalpha}$,$ m{ extgamma}$)$^{26}$Mg reaction, crucial for stellar nucleosynthesis, confirming previous results and setting new limits on unmeasured resonances.

Contribution

First direct measurement of the $E_{ m{ extalpha}}^{lab}$ = 650 keV resonance strength with an upper limit, improving understanding of stellar reaction rates.

Findings

Confirmed the 830 keV resonance strength with reduced uncertainty.

Set an upper limit for the 650 keV resonance strength.

Measured the 851 keV resonance in $^{22}$Ne(p,$ m{ extgamma}$)$^{23}$Na with lower uncertainty.

Abstract

The $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ is an important reaction in stellar helium burning environments as it competes directly with one of the main neutron sources for the s-process, the $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ reaction. The reaction rate of the $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ is dominated by the low energy resonances at $E_{\alpha}^{lab}$ = 650 and 830 keV respectively. The $E_{\alpha}^{lab}$ = 830 keV resonance has been measured previously, but there are some uncertainties in the previous measurements. We confirmed the measurement of the $E_{\alpha}^{lab}$ = 830 keV resonance using implanted $^{22}$Ne targets. We obtained a resonance strength of $\omega\gamma$ = 35 $\pm$ 4 $\mu eV$, and provide a weighted average of the present and previous measurements of $\omega\gamma$ = 35 $\pm$ 2 $\mu eV$ with reduced uncertainties compared to previous studies. We also attempted to measure the strength of the predicted resonance at $E_{\alpha}^{lab}$ = 650 keV directly for the first time and found an upper limit of $\omega\gamma$ $\mathrm{<0.15}$ $\mu eV$ for the strength of this resonance. In addition, we also studied the $E_{P}^{lab}$= 851 keV resonance in $^{22}\rm{Ne}(p,\gamma)^{23}\rm{Na}$, and obtained a resonance strength of $\omega\gamma$ = 9.2 $\pm$ 0.7 eV with significantly lower uncertainties compared to previous measurements.