The astrophysical factor for Be7(p,γ)B8 at zero energy, S17(0), is determined from an analysis of Pb208(B8, p+Be7)Pb208 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 S17(0) from the calculated breakup cross section. The main result of the present paper is S17(0)=20.9-1.9+2.0 eV b. The error consists of 8.4% experimental systematic error and the error due to the ambiguity in the s-wave p-Be7 scattering length. 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 multistep processes of all-order in the present work. The p-Be7 interaction potential used in the CDCC calculation is also used in the ANC analysis of Be7(p,γ)B8. The value of S17(0)=21.7-0.55+0.62 eV b obtained is consistent with the previous one obtained from a precise measurement of the p-capture reaction cross section extrapolated to zero incident energy, S17(0)=22.1±0.6 (expt) ±0.6 (theo) eV b, where (theo) stands for the error in the extrapolation. Thus, the agreement between the values of S17(0) obtained from direct Be7(p,γ)B8 and indirect B8-breakup measurements is significantly improved.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics