Be7(p,γ)8

Abstract

We study the nonresonant part of the 7 Be(p, γ) 8 B reaction using a threecluster resonating group model that is variationally converged and virtually complete in the 4 He+ 3 He+p model space. The importance of using adequate nucleon-nucleon interaction is demonstrated. We find that the low-energy astrophysical S-factor is linearly correlated with the quadrupole moment of 7 Be. A range of parameters is found where the most important 7 Be and 7 Li properties are reproduced simultaneously; the corresponding S-factor at E cm = 20 keV is 24.6 − 26.1 eV·b.PACS numbers: 25.40. Lw, 21.60.Gx, 27.20.+n, 95.30.Cq Typeset using REVT E X

Effects of 8B size on the low-energy 7Be(p,γ)8B cross section

“…[9] we demonstrated that there is a linear correlation between the zero-energy astrophysical S factor, S 17 (0), of the 7 Be(p, γ) 8 B reaction and the quadrupole moment of 7 Be, Q 7 . The Q 7 quadrupole moment has not been measured yet, but in Ref.…”

“…The absolute scale of the S 17 (0) − Q 7 correlation, however, depends on the applied effective nucleon-nucleon (N − N) interaction. For our preferred MN interaction this resulted in S 17 (0) = 25 − 26.5 eV b [9]. Other interactions gave slightly larger or smaller S 17 (0) values, but these interactions were found to be inferior to the MN force for other observables.…”

“…The Q 7 quadrupole moment has not been measured yet, but in Ref. [9] we have predicted it to be between −6 e fm 2 and −7 e fm 2 . The absolute scale of the S 17 (0) − Q 7 correlation, however, depends on the applied effective nucleon-nucleon (N − N) interaction.…”

“…In Ref. [9] we have shown that the zero-energy cross section of the 7 Be(p, γ) 8 B reaction scales linearly with the, unfortunately yet unknown, quadrupole moment of 7 Be. In the present paper we extend this study and investigate the relation between the zero-energy cross section and several 8 B "size" properties.…”

“…As this model has been discussed before we refer the reader to Refs. [10,9] for details of the theoretical background. As customary in nuclear astrophysics we define the cross sections in terms of the astrophysical S factor…”