Speaker
Description
The NeNa and MgAl cycles are relevant to the synthesis of Ne, Na, and Mg isotopes: a detailed knowledge of the involved nuclear processes is fundamental to determine the nucleosynthesis during various stages of stellar evolution, in particular in the Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) phases, as well as in Novae explosions. Key reactions of these cycles are also thought to be the main agents of the observed anti-correlations in O-Na and Al-Mg abundances exhibited by the stars of Galactic globular clusters.
The experimental activity at the LUNA-400 gas target line is presently focused on the study the $^{20}$Ne(p,$\gamma$)$^{21}$Na reaction at proton energies below 400 keV. Having the slowest reaction rate, the $^{20}$Ne(p,$\gamma$)$^{21}$Na reaction controls the speed at which the entire Ne-Na cycle proceeds: existing uncertainties on the cross section severely affect the estimated elements production in the whole NeNa cycle.
During 2021, the resonance at $E_R$ = 366 keV in the $^{20}$Ne(p,$\gamma$)$^{21}$Na reaction has been studied: a complete scan was made with the two HPGe detectors installed on the setup and the resonance strength and branching ratios for the $\gamma$-ray cascade measured in detail. The effect of the beam energy straggling was also measured in order to properly account for that in the analysis and to minimize the related uncertainty.
Moreover, the low background of the LUNA facility has already allowed to observed gamma transitions of the direct capture process down to proton energies of 260 keV. This is an important confirmation that the experimental setup is sensible to this component over a broad energy range.
In the talk the experimental setup will be described, and the results discussed.
