E2 component in subcoulomb breakup of 8B

We calculate the angular distribution and total cross section of the 7Be fragment emitted in the break up reaction of 8B on 58Ni and 208Pb targets at the subcoulomb beam energy of 25.8 MeV, within the non-relativistic theory of Coulomb excitation with proper three-body kinematics. The relative contributions of the E1, E2 and M1 multipolarities to the cross sections are determined. The E2 component makes up about 65% and 40% of the 7Be total cross section for the 58Ni and 208Pb targets respectively. We find that the extraction of the astrophysical S-factor, S17(0), for the 7Be(p,γ)8B reaction at solar energies from the measurements of the cross sections of the 7Be fragment in the Coulomb dissociation of 8B at sub-Coulomb energies is still not free from the uncertainties of the E2 component.