The 'lithium problem' in Big Bang Nucleosynthesis (BBN) has recently focused on the reactions involving 7 Be. The 6 Li(p, γ) 7 Be reaction can provide us not only the information for destroying 6 Li but also the information for producing 7 Be. In the present work, the proton spectroscopic factor in 7 Be was extracted to be 0.70 ± 0.17 from the angular distribution of 7 Be(d, 3 He) 6 Li at Ec.m. = 6.7 MeV. The value was then used to compute the direct component of the astrophysical 6 Li(p, γ) 7 Beg.s. S(E) factors and determine the resonance parameters from the total S(E) factors. PACS numbers: 26.35.+c, 21.10.Jx, 25.40.Lw
I. INTRODUCTIONAccording to the standard Big Bang model, the universe starts from a singularity of extremely high temperature and density. The primordial nucleosynthesis takes place between 10 seconds and 20 minutes right after Big Bang. Big Bang Nucleosynthesis (BBN) [1] is the starting point of the elements, which can tell us not only the evolution of the elements but also the thermal history of the early universe. In standard theory of BBN (SBBN), the abundances of 2 H, 3 He, 4 He and 7 Li depend on only one cosmological parameter, the baryon-to-photon ratio, which can be constrained with high accuracy measurement of the Cosmic Microwave Background (CMB). Using the data from the precision observations of the CMB radiation with the Wilkinson Microwave Anisotropy Probe (WMAP) [2,3], the BBN predictions for the primordial abundances of 2 H and 4 He are in good agreement with the observations. However, for 7 Li, there is a significant discrepancy between BBN predictions and the abundance derived from metal poor halo stars [4].The results from SBBN network calculations [5] showed that the primordial 7 Li were mainly produced from 7 Be via the electron capture decay. Such been the case, the 'lithium problem' in BBN should be focused on the reactions involving 7 Be. The 3 He(α, γ) 7 Be reaction is the leading process to produce 7 Be, which has been studied with great efforts [7][8][9][10][11][12][13][14][15]. As a supplementary reaction to produce 7 Be, the 6 Li(p, γ) 7 Be reaction, which is crucial for the consumption of 6 Li and the formation of 7 Be, has also attracted wide attention in the past years [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. It is commonly believed that the direct capture dominates the 6 Li(p, γ) 7 Be reaction at low energy. However, He et al. [31] found a broad resonance in the astrophysical interesting energy region in 2013, which will change the evaluation for the contribution of this reaction to the big bang nucleosynthesis and the 7 Be(p, γ) 8 B solar neutrino reaction. The reproduced astrophysical S(E) factors using R-matrix method can not well describe the experimental data, and further study will help us to understand the properties of this low energy resonance.In the present article, we will reanalyze the angular distribution of 7 Be(d, 3 He) 6 Li measured in inverse kinematics with the secondary 7 Be beam, which was described detail in o...
