$\pi \to \pi \pi$ results in nuclei

The Crystal Ball ($CB$) collaboration at $BNL$ has recently presented results regarding a study of the ${\pi }^{-}A\to {\pi }^0{\pi }^0{A}^{\mathrm{\prime }}$ reaction on $H, D, C, Al$and$Cu$,usinganearly4$\pi$detector\mathrm{.}Similarresults,butforthe$\pi^+ A \to \pi^+\pi^{\pm} A^\prime$reactionon$^{2}H$,$^{12}C$,$^{40}Ca$, and ${}^{208}Pb$, have been published earlier by the $CHAOS$ collaboration at $TRIUMF$. In this Brief Report a comparison of the results of the two measurements is made, which shows that the $CHAOS$ and $CB$ data share relevant common features. In particular, the increase in strength as a function of A seen in the near-threshold ${\pi }^{+}{\pi }^{-}$ invariant mass spectra reported by the $CHAOS$ group, is also seen in the ${\pi }^0{\pi }^0$ CB data, when the results from the two groups are compared in a way which accounts for the different acceptances of the two experiments.