Elastic scattering of 30 MeV positive and negative pions from nickel isotopes

Abstract

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 ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ cross sections while no effect was observed in the ${\ensuremath{\pi}}^{+}$ cross sections. The cross sections were compared to predictions made by various optical model calculations. In general, both ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ cross sections were poorly described and the ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ isotope effects were not well reproduced. Anomalous effects first observed in pionic atoms may also appear in the present data.