ALPHA-O-16 AND ALPHA-N-15 OPTICAL POTENTIALS IN THE RANGE BETWEEN 0 AND 150 MEV

A unified description of scattering cross sections as well as bound and quasibound states for the systems alpha + O-16 and alpha + N-15 is presented. Optical potentials have been extracted from the analysis of elastic alpha-scattering data on O-16 and N-15 in a wide range of energies. Special emphasis was given to the alpha + O-16 scattering at energies near the Coulomb barrier. The real part of the potential was calculated using the double-folding procedure. Effective nucleon-nucleon interactions with different density dependence as well as zero-range and finite-range knock-on-exchange potentials are investigated. The dispersive part of the real potential was calculated using the dispersion relation of the optical potential. Together with the dominating channel potential it reproduces the observed energy dependence of the volume integral of the real part of the potential. We calculate the energies and other properties of bound and resonance alpha-cluster states in Ne-20 and F-19 and find good agreement with the experimental data. As an application of the derived energy dependence of the optical potential we calculate alpha + O-16 excitation functions in the energy range 10 to 30 MeV. In this region strong resonances in the compound system are observed.