Pion absorption in heavy nuclei

Cross sections have been measured for proton emission following ${\mathrm{\pi }}^{+}$ absorption on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ for pion kinetic energies of 50, 100, 150, and 200 MeV by using a large-solid-angle bismuth germanate detector array. An increasing fraction of transitions to states of large missing energy and with particles other than protons is observed as the energy and mass increase.