Large basis shell model analysis of ¹⁴N(γ,π⁺)¹⁴C_g.s. reaction

The ¹⁴N(γ,π⁺)¹⁴C_g.s. cross section at Eγ=173 MeV has been calculated using shell model wave functions determined in complete (0+2)ℏω and (0+2+4)ℏω shell model spaces. Using the (0+2+4)ℏω shell model wave functions yields an improvement over older results obtained with Cohen-Kurath wave functions by a factor of 2, but still overpredicts the back-angle data. When correlated with analyses of inelastic electron and proton scattering from ¹⁴N, the present results indicate the need for an improved shell model calculation and possibly an improved description of the elementary pion production process in nuclei.