The investigation of strangeness photoproduction in the threshold region at ELPH-Tohoku

The strangeness photoproduction processes near the threshold have been intensively studied by measuring image in reactions such as image. There has been no reliable data on the neutron and as a consequence theoretical investigation suffered seriously from the lack of the data. We have an effort to measure the image reaction in the image (image) decay channel of image (Λ) using a liquid D2 target and internally-tagged photon beams (image) at Research Center for Electron Photon Science (ELPH), Tohoku University. We have renewed the spectrometer (NKS2) and took data with a liquid D2 target in 2005–2007. More recently, we took data in 2010 after a detector upgrade in the vertex region to substantially increase the acceptance. The results of Λ single measurements on a deuterium target were obtained for differential cross-section as a function of momentum, as a function of angle, and integrated cross-section as a function of beam energy. The results are compared with recent theoretical studies: Isobar models (Kaon-MAID and Saclay-Lyon A) and a Regge-plus-Resonance model.