Photo-production of neutral kaons on 12C in the threshold region

The kaon photo-production process on 12C has been studied by measuring neutral kaons in the photon energy range of 0.8-1.1 GeV. Neutral kaons were identified by the invariant mass constructed from two charged pions emitted in the KS0→π+π− decay channel. The differential and integrated cross sections in the threshold photon energy region were obtained. The obtained momentum spectra were compared with a Spectator model calculation using elementary amplitudes of kaon photo-production given by recent isobar models. The present results provide the first information on the n(γ,K0)Λ reaction, which is expected to play an important role in constructing models of strangeness production by electromagnetic interactions. The experimental results show that the cross section of C12(γ,K0) is of the same order as that of C12(γ,K+) and suggest that a slightly backward K0 angular distribution is favored in the γn→K0Λ process.