Status of the experiment of Lambda-n interaction measrement via FSI egffect in gamma+d reaction at ELPH, Tohoku Univ.

Hypernuclear spectroscopy is one of the most powerful tools to extract Hyperon-Nucleon interaction. On the other hand, recent studies of $^{4}_{\Lambda}$H and $^{4}_{\Lambda}$He show that there is a larger difference of binding energies between the two light hypernuclei than theoretical calculation. The problem is called charge symmetry breaking in $\Lambda$-$N$ interaction. It means that there is difference between $\Lambda$-$p$ and $\Lambda$-$n$ interactions or the other effect. There are data about $\Lambda$-$p$ scattering, but no data about $\Lambda$-$n$ scattering due to difficulty of the experiment. One of the keys to solve the problem is to measure $\Lambda$-$n$ with enough statistics. We proposed the experiment to obtain $\Lambda$-$n$ interaction via final-state-interaction effect in $\gamma + d \rightarrow K^{+} + \Lambda + n$ reaction at ELPH, Tohoku University. We will present the status of the experiment including the detector development in this talk.