Determination of S₁₇ from ⁸B breakup by means of the method of continuum-discretized coupled-channels

The astrophysical factor for ⁷Be(p, γ)⁸B at zero energy, S₁₇(0), is determined from an analysis of ²⁰⁸Pb(⁸B, p+⁷Be)²⁰⁸Pb at 52 MeV/nucleon by means of the method of continuum-discretized coupled-channels (CDCC) taking account of all nuclear and Coulomb breakup processes. The asymptotic normalization coefficient (ANC) method is used to extract S ₁₇(0) from the calculated breakup cross section. The main result of the present paper is S₁₇(0)=20.9_-1.9^+2.0eVb. This value of S₁₇(0) differs from the one extracted with the first-order perturbation theory including Coulomb breakup by dipole transitions: 18.9 ± 1.8 eV b. It turns out that the difference is due to the inclusion of the nuclear and Coulomb-quadrupole transitions and multi-step processes of all-order in the present work. Our main result of S₁₇(0) is consistent with the value obtained from a precise measurement of the p-capture reaction cross section extrapolated to zero incident energy, S ₁₇(0) = 22.1 ± 0.85 eV b. Thus, the agreement between the values of S₁₇(0) obtained from direct ⁷Be(p, γ) ⁸B and indirect ⁸B-breakup measurements is significantly improved.