The total cross section and pion angular distributions for the reaction ${}^{12}\mathrm{C}(\gamma ,{\pi }^0)$ have been measured within 25 MeV of threshold using tagged photons and a large acceptance ${\pi }^0$ spectrometer at the Saskatchewan Accelerator Laboratory (SAL). The total cross section is in agreement with earlier measurements from Saclay and Mainz. The elementary $P$-wave photoproduction amplitude $P_3^{\mathrm{}(+)\mathrm{}}$ has been determined from a distorted-wave impulse-approximation analysis of the nuclear data and compares favorably with the corresponding free-nucleon amplitude in the threshold region. The incoherent contribution from the 4.43 MeV ${(2\mathrm{}}^{+})$ state has been deduced from the pion angular distributions and is in agreement with previous experimental estimates.

• Received 24 January 1997

DOI:https://doi.org/10.1103/PhysRevC.55.2923