The reaction Li(a, n ) "B is of interest in inhomogeneous big bang nucleosynthesis. A distorted wave Born approximation calculation employing folding potentials is presented for energies below the Coulomb barrier. The recently observed resonance at about 540 keV center-of-mass energy can be reproduced. The astrophysical S factor is calculated for the ground-state transition as well as for the transitions to the first four excited states of "B. The reaction rate is derived and compared to literature data. The inclusion of the excited states increases the rate by a factor of 1.5 compared to the groundstate transition.PACS number(s): 25.40.Hs, 98.80.Ft, 24.50.+ g

Angular distributions of protons, deuterons, tritons and alpha-particles emitted from the reactions in the d + 9Be-system at Ee = 7 MeV as well as excitation functions at selected angles in the energy range Ea= 6.5-7.5 MeV (LAB) were measured. The potential part of the elastic scattering is described by the phenomenological optical model. The compound nucleus contribution to all exit channels is determined using the Hauser-Feshbach model. The collective excitation of the 2.43 MeV excited state of 9Be and transfer processes are analysed within the DWBA formalism. The analyses suggest a significant contribution of five-nucleon transfer to the (d, 4He) channel. Nuclear Reactions: 9Be(d, p), 9Be(d, d), 9Be(d, t), 9Be(d, 4He), measured: a(O), Ela b = 7 MeV, o-(O, E), Elab = 6.5-7.5 MeV, optical model, Hauser-Feshbach model and DWBA analysis.

The structure of states of nuclei with three and five active nucleons in the 1s0d and 1p0f shells is studied in the framework of the collective pair approximation. The collective pairs determined by diagonalizing the Hamiltonian in the space of two nucleons outside closed shells are considered as building blocks to describe a nucleus with 2k+1 nucleons in terms of k pairs coupled to one nucleon. It is shown that the low-lying, shell-model spectrum can be described quite well by considering only a selected subset of all possible collective pairs.

No abstract