Two-neutron transfer in Be7+Be9 collisions

Elastic scattering and transfer cross sections for the Be-7 + Be-9 system have been measured at E-lab = 23.1 MeV using the Be-7 radioactive secondary beam produced at Radioactive Ion Beams in Brazil facility at the University of Sao Paulo. The elastic scattering has been measured by detecting the Be-7 scattered at forward angles in the laboratory system. The transfer reaction Be-9(Be-7, Be-9)Be-7 was identified by detecting the Be-9 scattered at the same laboratory angles. The elastic angular distribution has been analyzed by optical model calculations using a Woods-Saxon form factor whose parameters have been varied to best reproduce the experimental data at forward angles. Coupled reaction channels calculations (CRC) have been performed to describe the transfer, considering the coupling to the transfer channel and including contributions to the ground state and to the first excited state of Be-7(1/2-; 429 keV) in the final state. The spectroscopic amplitudes used in the CRC calculation have been derived from shell-model calculations. Similar CRC calculations were applied to existing Be-9(p, t)Be-7 data to check the consistency of our results results for the (Be-7, Be-9) transfer reaction.