The $\pi\pi$ interaction in nuclear matter from a study of the $\pi^{+}A \to \pi^{+}\pi^{\pm}A'$ reactions

The pion-production reactions $\pi^+ A \to \pi^+\pi^{\pm} A'$ were studied on $^{2}H$, $^{12}C$, $^{40}Ca$, and $^{208}Pb$ nuclei at an incident pion energy of $T_{\pi^{+}}$=283 MeV. Pions were detected in coincidence using the CHAOS spectrometer. The experimental results are reduced to differential cross sections and compared to both theoretical predictions and the reaction phase space. The composite ratio $\cal C