Preprint CNP - 95 / 18 Astrophysical S - factor of the 7 Be ( p , γ ) 8 B reaction from Coulomb dissociation of 8 B ∗

The Coulomb dissociation method to obtain the astrophysical S-factor, S 17 (0), for the 7 Be(p, γ) 8 B reaction at solar energies is investigated by analysing the recently measured data on the breakup reaction 208 Pb(8 B, 7 Be p) 208 Pb at 46.5 MeV/A beam energy. Breakup cross sections corresponding to E1, E2 and M 1 transitions are calculated with a theory of Coulomb excitation that includes the effects of the Coulomb recoil as well as relativistic retardation. The interplay of nuclear and Coulomb contributions to the breakup process is studied by performing a full quantum mechanical calculation within the framework of the distorted-wave Born Approximation. In the kinematical regime of the present experiment, both nuclear as well as Coulomb-nuclear interference processes affect the pure Coulomb breakup cross sections very marginally. The E2 cross sections are strongly dependent on the model used to describe the structure of 8 B. The value of S 17 (0) is deduced with and without E2 and M 1 contributions added to the E1 cross sections and the results are discussed.