Cross sections for the 7 Be͑p, g͒ 8 B reaction have been measured for E c.m. 0.35 1.4 MeV using radioactive 7 Be targets. Two independent measurements carried out with different beam conditions, different targets, and detectors are in excellent agreement. A statistical comparison of these measurements with previous results leads to a restricted set of consistent data. The deduced zeroenergy S factor S͑0͒ is found to be 15%-20% smaller than the previously recommended value. This implies a 8 B solar neutrino flux lower than previously predicted in various standard solar models.[S0031-9007(97)

We have measured the cross section of the 7Be(p,gamma)8B reaction for E(c.m.) = 185.8, 134.7, and 111.7 keV using a radioactive 7Be target (132 mCi). Single and coincidence spectra of beta+ and alpha particles from 8B and 8Be* 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.