Scattering of Be7 and B8 and the astrophysical S17 factor

Abstract

Measurements of Be7 scattering at 87 MeV on a melamine (C3N6H6) target and of B8 at 95 MeV on C were performed. For Be7 the angular range was extended over previous measurements and monitoring of the intensity of the radioactive beam was improved. The measurements provide a renormalization of the absolute cross section of existing data on the proton transfer reaction N14(Be7,B8)C13 and lead to improved optical-model potentials used in the incoming and outgoing channels for the distorted-wave Born approximation analysis. The results yield an updated determination of the asymptotic normalization coefficient for the virtual decay B8 → Be7+p. The new value, Ctot2(8B)=0.466±0.049 fm-1, is slightly larger than, but consistent with, the previous result. This implies an astrophysical factor, S17(0)=18.0±1.9 eV b, for the solar neutrino-generating reaction Be7(p,γ)B8. © 2006 The American Physical Society.