Energetic charged particle yields induced by pions on complex nuclei

The spectra of protons ($60<\mathrm{}{E}_p<200\mathrm{}$ MeV) and deuterons ($80 \mathrm{MeV}<E_d$) produced by 100- and 220-MeV ${\pi }^{+}$ and ${\pi }^{-}$ on Al, Ni, and Ta targets were measured. The shapes of proton spectra are similar for ${\pi }^{+}$ and ${\pi }^{-}$, with absolute yields in ∼3:1 ratio; the yields vary as $\sim A^{\frac{2}{3}}$. The exception is the forward-angle yield at 100 MeV where the proton spectra with ${\pi }^{+}$ are different in shape from ${\pi }^{-}$, the yield ∼5 times as high, and the target dependence is $\sim A^{\frac{1}{3}}$. This pattern is not readily understood at the present time.