The elastic scattering of ¹⁶O from even Ca Isotopes near the Coulomb barrier

It has been pointed out that a detailed study of the elastic scattering of charged particles from nuclei, at incident energies near the Coulomb barrier, can yield rather accurate information on the relative size of a series of isotopes. An optical model analysis can yield unambiguous results for two parameters; the value of the total potential at its maximum V_B and the ''Rutherford radius'', r_R, the distance between them the point of the maximum of the total potential and the center of the nucleus. The present investigation employed the elastic scattering of ¹⁶O from ^40,44,48Ca to study the relative sizes of these nuclei. The Ruther- ford radius of these ca isotopes was found to vary approximately as A^1/3. The behavior of r_R which concerns the mass distribution, contrasts markedly with the charge radii which have been found to be almost the same for the three calcium isotopes. The scattering of ¹⁶O from calcium was found to exhibit the same smooth behavior and the same general features as in the scattering of alpha particles from lead. Since a high degree of accuracy is required in the determination of the differential cross section, the elastic scattering from calcium and gold was measured simultaneously by employing a composit target and, then, the two cross sections were compared directly. The elastic scattering from gold was pure Rutherford scattering over the energy range covered in this study. (author)