Electromagnetic dissociation of 8B and the astrophysical S factor for 7Be(p,gamma)8B

We present S factor data obtained from the Coulomb dissociation of 83 MeV/nucleon 8B, and analyze 7Be longitudinal momentum distributions measured at 44 and 81 MeV/nucleon using a potential model, first-order perturbation theory, and dynamical solution of the time-dependent Schroedinger equation. Comparing our results with independent continuum-discretized coupled channels calculations, we examine the reaction model and beam energy dependence of the E2 contribution to the dissociation cross section. By fitting radiative capture and Coulomb breakup data taken below relative energies of 400 keV with a potential model constrained by 7Be + p elastic scattering data, we examine the mutual consistency of recent S17 measurements. Evaluating the central values consistently and the extrapolation uncertainties on a case-by-case basis, we take a weighted average of the results of four direct and three indirect measurements to obtain a recommended value for S17(0) of 19.0 +/- 1.0 eV b (95% confidence level)