Direct observation of multiple-scattering processes in pion absorption

In the angular correlation of the (${\pi }^{\mathrm{-}}$,pp) reaction, two rather sharp peaks were observed for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and C. These peaks were considered to be associated with two-step processes; one is pp-pp scattering after the (${\pi }^{\mathrm{-}}$,pn) reaction, and the other is the ${\pi }^{\mathrm{-}}$p-${\pi }^0$n reaction followed by the (${\pi }^0$,pp) reaction. The intranuclear cascade model reproduced very well the two peaks. These results show that two-step processes are important in pion-absorption reactions for light nuclei.