E2 component in subcoulomb breakup of 8B

Abstract

We calculate the angular distribution and total cross section of the ^{7}Be fragment emitted in the break up reaction of ^{8}B on ^{58}Ni and ^{208}Pb 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 ^{7}Be total cross section for the ^{58}Ni and ^{208}Pb targets respectively. We find that the extraction of the astrophysical S-factor, S_{17}(0), for the ^{7}Be(p,\gamma)^8B reaction at solar energies from the measurements of the cross sections of the ^{7}Be fragment in the Coulomb dissociation of ^{8}B at sub-Coulomb energies is still not free from the uncertainties of the E2 component.