Positive and negative pion elastic scattering on [58]Ni, [60]Ni, and [64]Ni at 50 MeV and 65 MeV

Elastic scattering data was successfully taken using the new "Clamshell" spectrometer. Angular distributions of elastic differential cross sections were obtained at 50 MeV and 65 MeV using positive and negative pions scattered from ⁵⁶Ni, ⁶⁰Ni, and ⁶⁴Ni.

The data were compared to predictions made using the MSU optical potential, The π⁺ data agreed fairly well with the predictions at both 50 MeV and 65 MeV while the corresponding π⁻ data significantly disagreed with the predictions.

The absorption parameters in the MSU potential were varied in an attempt to fit the data. A suitable fit was achieved for both π⁺ and π⁻ data at 50 MeV and 65 MeV. The real part of the p-wave absorption parameter was well determined but showed two distinct values for π⁺ and π⁻ indicating that there is a separate potential for π⁺ and π⁻ or that the absorption part of the potential is inadequately formulated.