The $\gamma n \to K^0 \Lambda$ photoproduction studied with an electromagnetic calorimeter complex FOREST

Nucleon resonance have been experimentally studied by means of meson production reactions for understanding low-energy scale QCD. Photoproduction is one of the useful tools to reveal properties of excited nucleons. Indeed, the $\pi$ and $\eta$ photoproduction reactions have been intensively investigated until now. Kaon photoproduction is the best probe to study highly excited nucleons, which hardly couple to $\pi N$ and $\eta N$. Simultaneous $K^0 \Lambda$ production is more advantageous than $K^+ \Lambda$ production which is reported by many experimental groups. It is because the kaon exchange is forbidden in the $K^0 \Lambda$ photoproduction, and because Born term contribution is small. The $\gamma d \to (K^0 \Lambda) p \to (\pi^0 \pi^0 p \pi^-)p$ reaction is experimentally investigated with an electromagnetic calorimeter FOREST at Research Center for Electron Photon Science, Tohoku University. The $K^0$ and $\Lambda$ particles are clearly observed in $\pi^0 \pi^0$ and $\pi^- p$ invariant mass distributions. We will present the current status of the exclusive $\gamma n \to K^0 \Lambda$ reaction.