The sums in the potential scattering series are carried out by permitting only one large angle scattering. An early result of Schiff is thus rederived and in the process the connection between it and the recent successful work of Chen is made clear. The amplitudes are convenient to use. The results are applied to the local Laplacian optical potential used in pion-nucleus scattering. The large angle amplitude is very sensitive to three different treatments of the coordinate systems transformation of the $\pi N$ amplitude that have been proposed.

NUCLEAR REACTIONS Large angle potential scattering theory; $\pi$-nucleus optical potentials, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$($\pi$,$\pi$) calculated $\sigma \left(\theta \right)$.

• Received 21 July 1980

DOI:https://doi.org/10.1103/PhysRevC.24.1152