Differential cross sections for ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\gamma , {\pi }^{+}){}_{}{}^{13}{}_{}{}^{}\mathrm{B}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$ at $E_{\gamma }=194\mathrm{}$ MeV ($T_{\pi }\cong 40$ MeV) were measured at seven angles from 30° to 150° encompassing the momentum transfer range $0.6<~q<~1.5$ ${\mathrm{fm}}^{-1\mathrm{}}$. These results are compared with several distorted-wave impulse-approximation calculations with and without core polarization. We observe serious discrepancies between theory and experiment and also among the various calculations.

NUCLEAR REACTIONS ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\gamma , {\pi }^{+}){}_{}{}^{13}{}_{}{}^{}\mathrm{B}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$, $E_{\gamma }=194\mathrm{}$ MeV; measured $\sigma \left(\theta \right)$, $\theta =30-150\mathrm{}°$, $\Delta \theta =20\mathrm{}°$. Enriched target. Results compared to DWIA calculations.

• Received 30 September 1982

DOI:https://doi.org/10.1103/PhysRevC.27.443