Pion-calcium scattering in the α-particle model

Elastic π-40Ca scattering in the region of the first pion-nucleon resonance is calculated within the optical limit of Glauber theory on the basis of the naive-α- particle model. When acccount is taken of the strong short-range repulsion between pairs of α-particles, the predicted cross sections become quite close to those derived from the conventional nucleon model. However both predictions can be quite accurately parameterised as fuzzy black discs, and the significance of this for future experiments is briefly discussed. (Auth.)