Nuclear structure approach to the calculation of the imaginary alpha-nucleus optical potential

Abstract

A microscopic calculation of the second-order imaginary optical potential for $^{40}\mathrm{Ca}$($\ensuremath{\alpha}$,$\ensuremath{\alpha}$) is made for incident energies of 31 and 100 MeV using random phase approximation transition densities for intermediate excited states. The projectile is treated as an elementary particle, and the alpha-nucleon interaction is normalized by fitting ${3}^{\ensuremath{-}}$ inelastic cross sections with a folded M3Y potential. The use of an optical Green's function for the intermediate propagator is found to be important. Equivalent local potentials are obtained and used to calculate elastic scattering cross sections. Agreement with low-angle experimental data is fair at 31 MeV but at 100 MeV the calculated cross sections indicate much too little absorption.NUCLEAR REACTIONS ($\ensuremath{\alpha}$,$\ensuremath{\alpha}$) scattering, calculation of imaginary optical potential at $E=31 \mathrm{and} 100$ MeV.