Pion Photoproduction and the Role of the Delta -

The differential cross sections for the reaction ^{14}C(gamma,pi ^-)^{14}N leading to the ground state and first two excited states of ^ {14}N were measured at a photon energy of 184 MeV and pion lab angles of 45^circ, 60^circ, and 80^ circ. Of particular interest is the reaction leading to the first excited state of ^ {14}N, which is a pure E0 transition and is dominated by the Delta resonance. The experiment was performed using the tagged photon beam of the Saskatchewan Accelerator Laboratory using plastic scintillator range telescopes to detect the pions. Considerable discrepancy is found between the data and theoretical calculations. In particular, the calculations greatly underpredict the data for the reaction leading to the first excited state of ^{14}N.