Status of experiment for ? n interaction measurement via final state interaction in ?d ? K ⁺? n production

Research on nuclear forces between the nucleon and the hyperon has been studied mainly on experiments on measuring the binding energy of hypernuclei. We thought that we understood the hyperon-nucleon force because theoretical models based on experimental data could reproduce many hypernuclear data. However, for recent H?4 (pnn?) and He?4 (ppn?) data, the theoretical ? ? model does not reproduce the binding energies of the ground and excited states. In these two hypernuclei, only p and n are replaced by one, and the expected binding energy is simply expected to be dominant due to the effect of Coulomb force. Experimental data show differences that cannot be explained by the theoretical model and the problem called charge symmetry breaking (CSB) in ?N interaction. The key to solving the problem is to measure ?n forces that have not been measured with good accuracy. To measure the force between ? and n, which cannot perform direct scattering experiments, we are preparing an experiment to measure the K+ production cross-section modified by the ?n final state interaction in the ?d?K+?n reaction. The experiment will be performed with a real photon beamline generated from a 1.3 GeV electron synchrotron in Research Center for Electron Photon Science (ELPH), Tohoku University. In the beamline, we have been conducting K0? production experiments using the NKS2 spectrometer. We are developing a new detector to measure K+, and report on it.