Experimental study of proton-induced nuclear reactions in ^6,7Li

The ⁶Li(p,α)³He and ⁷Li(p,α)⁴He reaction cross sections were obtained for E = 90–580 keV and E = 90–1740 keV, respectively. R-matrix and polynomial fits to the bare astrophysical S-factor confirmed, with improved accuracy, previous work data, yielding S_b(0) = 3.52 ± 0.08 MeV b, and 55.6^+0.8_−1.7 keV b for the ⁶Li and ⁷Li reactions, respectively. Therefore, the astrophysical consequences related to these two isotopes remain essentially unchanged. With the present work S_b(E) data, a reanalysis of the low energy data for different environments—Li₂WO₄ insulator, Li metal, and PdLi_x alloys—confirms that the large electron screening effects can be explained by the plasma model of Debye applied to the quasi-free electrons in the metallic samples.