Further explorations of theα-particle optical model potential at low energies for the mass rangeA≈45–209

Abstract

The recent high-precision measurements of $\ensuremath{\alpha}$-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 $\ensuremath{\alpha}$ particles on nuclei within the mass number range $45\ensuremath{\le}A\ensuremath{\le}209$ [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 $\ensuremath{\sim}7%$ larger radius for the surface imaginary part of this spherical OMP. Improved input parameters based on recent independent data, particularly $\ensuremath{\gamma}$-ray strength functions, but no empirical rescaling factor of the $\ensuremath{\gamma}$ and/or neutron widths have been involved within statistical model calculation of the corresponding $(\ensuremath{\alpha},x)$ reaction cross sections.