ELASTIC-SCATTERING OF B-11 FROM BI-209 IN THE ENERGY-RANGE LESS-THAN-OR-EQUAL-TO-E-LESS-THAN-OR-EQUAL-TO-84.1 MEV

The elastic scattering of B-11 from Bi-209 has been measured at labora tory energies of 49.8, 51.3, 52.2, 52,8, 54.3, 55.8, 59,8, 64.8, 69.8, 74.8 and 84.1 MeV. These data have been analyzed using a microscopic optical model and the energy dependence of the real and the imaginary parts of the optical potential at near barrier energies has been deter mined. The ''threshold anomaly'' observed in the real part of the pote ntial is found to be consistent with the dispersion relation which con nects the real and the imaginary parts of the potential. Inelastic sca ttering and transfer reactions have also been measured at energies of 51.3, 55.8, 59.8 and 74.8 MeV, DWBA calculations for the 3(-) state in Bi-209 are made. From the measured transfer probabilities, using a se miclassical approach the strength of the form factors have been obtain ed. The fusion cross sections have been derived at these energies from the corresponding quasi-elastic scattering angular distribution data. The fusion cross sections calculated using the energy dependent barri ers extracted from the energy dependent real parts of the potential co mpare well with, that determined from quasi-elastic scattering data an d are also in good agreement with simplified coupled channels calculat ion for fusion incorporating important inelastic and transfer channels . (C) 1998 Published by Elsevier Science B.V.