Total and differential cross sections for the reaction ${}^6\mathrm{Li}(\gamma ,{\pi }^0)$ have been measured within 23 MeV of threshold using the tagged photon facility at SAL in conjunction with the ${\pi }^0$ spectrometer IGLOO. The differential measurements are the first to be reported in the threshold region, while the quality of the total cross section far surpasses previous investigations. The electric dipole amplitude for ${\pi }^0$ photoproduction has been deduced at threshold, and the relation to the corresponding free-deuteron amplitude as recently measured is examined within the context of an $\alpha -d$ cluster model of ${}^6\mathrm{Li}.$ The reduced P-wave amplitude $P_3^{\mathrm{}(+)\mathrm{}}/kq$ is deduced at threshold and is consistent with previous estimates from both the nucleon and nuclear sectors. The apparent stability of this amplitude as a function of environment remains a puzzle. Finally, the present cross sections compare favorably with the recent distorted-wave impulse approximation calculations of Kamalov et al.

• Received 15 April 1998

DOI:https://doi.org/10.1103/PhysRevC.59.2588