Elastic cross sections for the scattering of positive and negative pions from ${}_{}{}^{58}{}_{}{}^{}$,60,64Ni were measured at 30 MeV incident pion energy. A clear isotope effect was observed in the ${\pi }^{\mathrm{-}}$ cross sections while no effect was observed in the ${\pi }^{+}$ cross sections. The cross sections were compared to predictions made by various optical model calculations. In general, both ${\pi }^{+}$ and ${\pi }^{\mathrm{-}}$ cross sections were poorly described and the ${\pi }^{\mathrm{-}}$ isotope effects were not well reproduced. Anomalous effects first observed in pionic atoms may also appear in the present data.

• Received 15 April 1987

DOI:https://doi.org/10.1103/PhysRevC.36.1472