Study of the 22Ne(p; )23Na reaction at luna

The 22Ne(p; γ)23Na reaction, part of the neon-sodium cycle of hydrogen burning, may explain the observed anticorrelation between sodium and oxygen abundances in globular cluster stars. At the astrophysical energies, the presence of many resonances dominates the rate. The LUNA Collaboration measured for the first time three of them: Ep = 156:2, 189.5, and 259.7 keV. Recently, by using a high-efficiency setup, the uncertainties related to those three states have been lowered drastically and the direct component of the cross section was also measured. As a result, at a temperature of 0.1 GK, the error bar of the 22Ne(p;γ)23Na reaction rate is now reduced by three orders of magnitude. The new high-efficiency setup provides also a possibility to investigate the branching cascades, despite the limited resolution of the BGO detector.