Investigations on η’ photoproduction off quasi-free neutron

A preliminary study for the photoproduction reaction $\gamma n(p) \rightarrow \eta' n$ off deuteron target was performed by analysing the GRAAL experiment data. We looked for the $\eta'$ signal in the missing mass distribution of detected and identified neutrons in the forward direction. A first preliminary estimation of Beam Asymmetry $\Sigma$ near the threshold as a function of the meson center of mass polar angle was estimated. $\Sigma$ beam asymmetry measurements were compared with the ones published by GRAAL Collaboration for the $\eta'$ photoproduction reaction on free proton, the data agree with the experimental uncertainties. Further investigations on $\eta'$ photoproduction off quasi-free proton with GRAAL data are in progress.