Further explorations of the alpha-particle optical model potential at low energies for the mass range A=45-209

Abstract

The recent high-precision measurements of alpha-particle induced reaction data below the Coulomb barrier (B) make possible the understanding of limits and possible improvement of a previous optical model potential (OMP) for alpha-particles on nuclei within the mass number range 45<A<209 [M. Avrigeanu et al., Phys. Rev. C 82, 014606 (2010)]. An updated version of this potential is given in the present work concerning mainly an increased surface imaginary potential depth well below B for A>130. Moreover, underestimation of reaction cross sections for well-deformed nuclei is removed by using ~7% larger radius for the surface imaginary part of this spherical OMP. Improved input parameters based on recent independent data, particularly gamma-ray strength functions, but no empirical rescaling factor of the gamma and/or neutron widths have been involved within statistical model calculation of the corresponding (alpha,x) reaction cross sections.