Elastic Scattering And Fusion Cross Sections For Be-7,Li-7+Al-27 Systems

Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the Be-7+Al-27 system at E-lab=17, 19, and 21 MeV in the angular range theta(c.m.)=12(degrees)-43(degrees). An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the Li-7+Al-27 system at E-lab=10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the theta(lab)=12(degrees)-72(degrees) range and for fusion the alpha-evaporation spectra from the compound nucleus were measured in the angular range theta(lab)=52(degrees)-132(degrees) (142 degrees at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The alpha-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sections obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the Be-7+Al-27 and Li-7+Al-27 systems shows a similar and consistent behavior.