Abstract
The real potential derived by optical-model analysis of data on elastic scattering of alpha particles is used for calculation of barrier penetrabilities for all known alpha decay groups of even-even nuclei. The barrier penetration factors were calculated by numerical integration in the WKB approximation taking into account centrifugal barrier effects, but ignoring noncentral interactions. Using these penetration factors and the experimental alpha half-lives, the reduced level widths δ2 are calculated. Ratios of δ2 values for ground and excited-state alpha groups are tabulated as a set of reduced hindrance factors.