Total cross sections for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$($\gamma$,${\pi }^{-}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$($\gamma$,${\pi }^{-}$)${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ are evaluated in the impulse approximation, with use of the Blomqvist-Laget photoproduction operator and pion distorted waves. A peak at low energies and the falloff of the cross section with increasing energy are found to be consequences of the changing overlap of pion waves with nuclear transition densities.

• Received 15 June 1979

DOI:https://doi.org/10.1103/PhysRevLett.43.1476