Alpha-Particle Scattering from Even Tellurium Isotopes

Abstract

Angular distributions were measured for elastic and inelastic $\alpha$ scattering by isotopically enriched targets of tellurium-122, -124, -126, -128, and -130 by using the 42-MeV $\alpha$ beam of the Lewis 60-in. cyclotron. In each isotope, cross sections were measured for three excited states. These states were the one-phonon $2^{+}$ quadrupole, the two-phonon $4^{+}$, and the one-phonon $3^{-}$ octupole. Optical-model fits were made to the elastic scattering, and ambguities in the optical potentials were investigated for a wide range of optical-model parameters. Such ambiguities are readily explained by assuming that the elastic scattering occurs primarily at the outer edges of the potential, and more penetrating particles are strongly absorbed. Inelastic scattering to one-phonon states was analyzed by using a distorted-wave Born-approximation (DWBA) calculation. Deformation parameters in agreement with previously measured values were obtained for all the one-phonon states. A number of other states having small cross sections were excited in each isotope.