A formalism for distorted wave impulse approximation calculations of the $A({\pi }^{+},2p)B$ reaction to discrete states in nucleus $B$ is described. Assuming that the ${\pi }^{+}$ capture occurs on a deuteronlike structure in the target nucleus, calculations are presented covering a range of bombarding energies from 25 to 350 MeV and target nuclei from $A=16\mathrm{} \mathrm{to} 90$. In most cases, distortion effects arising from the interaction of the pion and two outgoing protons with the core are large, but primarily affect the magnitude of the cross section. Based on these calculations it is concluded that any more realistic calculation of pion absorption will require the inclusion of the interaction of the incoming and outgoing particles with the core.

NUCLEAR REACTIONS DWIA reaction theory of pion absorption on nuclei. ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(${\pi }^{+}$,$2p$), $T_{\pi }=25-350\mathrm{}$ MeV, calculate $\sigma ({\theta }_1,{\theta }_2,E_1)$.

• Received 20 July 1981

DOI:https://doi.org/10.1103/PhysRevC.24.2647