Low-energy measurement of the 7Be(p,γ)8B cross section

We have measured the cross section of the Be-7(p, gamma)B-8 reaction for E-c.m. = 185.8, 134.7. and 111.7 keV using a radioactive Be-7 target (132 mCi). Single and coincidence spectra of beta (+) and alpha particles from B-8 and Be-8* decay, respectively, were measured using a large acceptance spectrometer. The zero energy S factor inferred from these data is 18.5 +/- 2.4 eV b and a weighted mean value of 18.8 +/- 1.7 eV b (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.