Improved direct measurement of low-energy resonances in the 21Ne(p, γ) 22Na reaction

In the nova temperature range, 0.1 GK < T < 0.4 GK, several low-energy resonances dominate the 21Ne(p, γ ) 22Na reaction rate, which is currently affected by large uncertainties. We present a high-precision study of the resonances at Elab r = 127.3, 271.4, 272.3, 291.5, and 352.6 keV, measured directly at the Laboratory for Underground Nuclear Astrophysics in Italy. The strengths of the 127.3-, 271.4-, and 291.5-keV resonances are consistent with previous measurements within 1σ. However, for the 272.3- and 352.6-keV resonances, we report strength values of (129.9 ± 5.8) meV and (14.9 ± 0.8) meV, respectively, more than a factor of 1.5 higher than literature values. In addition, we report on new branching ratios for the 127.3-, 272.3-, and 352.6-keV resonances, leading to updated decay schemes. Finally, we present a revised thermonuclear reaction rate and investigate its impact on the NeNa nucleosynthesis.