Investigation of the Nuclear Surface by Means of the Elastic Scattering of Heavy Ions

An investigation has been made to determine the relevant parameters in the elastic scattering of alpha particles and heavy ions by nuclei. First, it has been shown by the analysis of typical alpha-particle scattering data that the qualitative features of the scattering are determined by two parameters: (a) the strength of the Coulomb interaction and (b) the radius of the ion-nucleus interaction. Second, two experiments with different nuclei have been performed where the above two parameters were kept fixed in order to determine whether differences in the scattering would appear due to a third parameter, say, the nuclear surface thickness. To enhance the differences between the two experiments two doubly-magic nuclei, ${\mathrm{O}}^{16}$ and ${\mathrm{Pb}}^{208}$, were used in the first scattering experiment while two aspherical nuclei, ${\mathrm{F}}^{19}$ and ${\mathrm{Tb}}^{159}$, were used in the second scattering experiment. Differences in the scattering did occur between the two experiments. However, it is not possible to conclude that the differences are due to nuclear surface effects because of the inclusion of inelastic scattering in the data taken in the second experiment. An indication that there is not a difference between the "surfaces" of the ${\mathrm{Pb}}^{208}$ and ${\mathrm{Tb}}^{159}$ nuclei has been shown by making a partial-wave analysis of data taken by Yntema of the elastic scattering of alpha particles by these same nuclei.