Measurements have been made of the attenuation cross sections for both ${\pi }^{+}$ and ${\pi }^{-}$ mesons on Al, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, Cu, Sn, Ho, and Pb nuclei. The measurements were made at several energies between 114 and 215 MeV. A new method of data analysis has been used to extract both the real and the imaginary parts of a Coulomb-distorted forward scattering amplitude $f_N\mathrm{}\left(0\right)\mathrm{}$. Insight into the nature of $f_N\mathrm{}\left(0\right)\mathrm{}$ is obtained by the comparison of experimental data with theoretical values calculated from a simple absorption model. This comparison demonstrates that much of the observed rotation of the forward amplitude, when plotted on an Argand diagram, can be attributed to the Coulomb phase contained in $f_N\mathrm{}\left(0\right)\mathrm{}$. Comparison is also made with results of similar experiments. Although the present results are in general agreement with previously published ones, some differences are noted for the heavier elements.

NUCLEAR REACTIONS Measured pion forward scattering amplitudes; Al, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, Cu, Sn, Ho, and Pb; $E=114-215\mathrm{}$ MeV; strong absorption model.

• Received 9 September 1982

DOI:https://doi.org/10.1103/PhysRevC.27.697