Direct study of the ²¹Ne(<i>p</i>,<i>γ</i>)²²Na reaction deep underground at LUNA

The 21 Ne( p , γ ) 22 Na reaction is part of the NeNa cycle, which contributes to hydrogen burning and nucleosynthesis in various stellar environments. The major astrophysical impact of this reaction is the production of the unstable nucleus of 22 Na, recognized by its distinct emission of 1.275 MeV stellar gamma rays. In order to constrain the production rate of 22 Na, it is necessary to determine the 21 Ne( p , γ ) 22 Na reaction rate from the contributions of a number of resonances at low energies. Here, we report on the direct and precise measurement of the E lab R = 272 keV resonance. The experimental setup and techniques are also described.