Coherent photoproduction ofπ+fromHe3

We have measured the differential cross section for the $\gamma$ ${}^3\mathrm{He}$ $\to \pi {}^{+}t$ reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid ${}^3\mathrm{He}$ target. The differential cross sections for the $\gamma$ ${}^3\mathrm{He}$ $\to \pi {}^{+}t$ reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.