The virtual photon spectrum shape and intensity within several MeV of the kinematic limit was measured for ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(e, {\pi }^{+}){}_{}{}^9{}_{}{}^{}\mathrm{Li}, e^{\prime }$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(e, {\pi }^{+}){}_{}{}^{16}{}_{}{}^{}\mathrm{N}, e^{\prime }(T_{\pi }=28\mathrm{} \mathrm{MeV}, {\theta }_{\pi }=90\mathrm{}°)$. The intensity over this interval is 1.25±0.10 times plane-wave virtual photon theory predictions; the shape agrees with theory within errors. Measurements on the proton 30 to 55 MeV below the end point agree with the intensity predictions of virtual photon theory within the errors (±8%).

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(e, {\pi }^{+})$, $E=180.4\mathrm{}$ MeV; ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(e, {\pi }^{+})$, $E=184.8\mathrm{}$ MeV; measured $\sigma (E_{\pi }, {90°}_{\mathrm{lab}})$ relative to ($\gamma , {\pi }^{+}$), near $E_{\pi }=28\mathrm{}$ MeV. ${}_{}{}^1{}_{}{}^{}\mathrm{H}(e, {\pi }^{+})$, $E=230\mathrm{}$ MeV; measured $\sigma (E_{\pi }, {90°}_{\mathrm{lab}})$ relative to ($\gamma , {\pi }^{+}$), near $E_{\pi }=18, 30$ MeV. Compared to PWBA virtual photon theory.

• Received 10 March 1980

DOI:https://doi.org/10.1103/PhysRevC.22.911