Low energy resonances in the 22Ne(p,g)23Na reaction directly observed at LUNA

The neon-sodium cycle of hydrogen burning influences the synthesis of the elements between 20Ne and 27Al in red giant stars and novae explosions. In order to reproduce the observed elemental abundances, the cross sections of the reactions involved in the nucleosynthesis process should be accurately known. The 22Ne(p,γ)23Na reaction rate is very uncertain because of a large number of unobserved resonances lying in the Gamow window. For proton energies below 400 keV, in the literature there are only upper limits for the resonance strengths. A new direct study of the 22Ne(p,γ)23Na reaction has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Gran Sasso using a windowless gas target and two high-purity germanium detectors. Several resonances have been observed for the first time in a direct experiment.