High precision 89Y(α,α)89Y scattering at low energies

Elastic scattering cross sections of the Y-89(alpha,alpha)Y-89 reaction have been measured at energies E-c.m. = 15.51 and 18.63 MeV. The high-precision data for the semimagic N = 50 nucleus Y-89 are used to derive a local potential and to evaluate the predictions of global and regional alpha-nucleus potentials. The variation of the elastic alpha-scattering cross sections along the N = 50 isotonic chain is investigated by a study of the ratios of angular distributions for Y-89(alpha,alpha)Y-89 and Mo-92(alpha,alpha)Mo-92 at E-c.m. approximate to 15.51 and 18.63 MeV. This ratio is a very sensitive probe at energies close to the Coulomb barrier, where scattering data alone is usually not enough to characterize the different potentials. Furthermore, alpha-cluster states in Nb-93=Y-89 circle times alpha are investigated.