TheC12(γ,K+) reaction in the threshold region

The first measurement of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(γ,${\mathit{K}}^{+}$) has been performed in a photon energy range of 0.8≤${\mathit{E}}_{\gamma }$≤1.1 GeV. The differential cross sections are compared with a calculation which assumes a quasi-free Λ-producing ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(γ,${\mathit{K}}^{+}$) process. The deviation of experimental values from the calculation is explained in terms of bound Λ residual states. The differential cross section ratio of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(γ,${\mathit{K}}^{+}$) to p(γ,${\mathit{K}}^{+}$)Λ is 4.2±0.6, which is in good agreement with a calculation using a semiclassical model.