Direct underground measurement of the 17O(p,α)14N reaction at LUNA

Abstract

The 17O(p, α)14N reaction plays a role in a number of stellar sites, including giant branch stars and novae. In particular, a narrow and isolated resonance at Ep=70 keV dominates the reaction rate at stellar temperatures around T9=0.01-0.1. A direct measurement of the 17O(p,α)14N reaction has been recently performed at the underground LUNA-400 accelerator in the Gran Sasso Laboratory, Italy. Protons were accelerated on a solid Ta2O5 target and the alpha particles emitted were detected with an array of silicon detectors. The background reduction afforded by the underground environment was instrumental in successfully carrying out the measurement. The setup was simulated and commissioned exploiting two well-known resonances at Ep=151 and 193 keV in 18O(p,α)15N and 17O(p,α)14N respectively. The strengths of the two resonances were found to be respectively meV and ωγ(193)=1.68±0.03stat±0.12 syst meV in good agreement with the literature. Analysis of data acquired on the Ep=70 keV resonance in 17O(p,α)14N reaction is currently underway.