Comprehensive measurement of ${\eta }^{\mathrm{\prime }}$ photoproduction off the proton at $E_{\gamma }<2.4$ $\mathrm{G}\mathrm{e}\mathrm{V}$

For the spectroscopy of nucleon resonances at the total energies from the ${\eta }^{\mathrm{\prime }}$-meson production threshold to $2.32$ $\mathrm{G}\mathrm{e}\mathrm{V}$, photon beam asymmetries of the reaction $\gamma p\to {\eta }^{\mathrm{\prime }}p$ were measured together with total and differential cross sections by analyzing the two decay modes ${\eta }^{\mathrm{\prime }}\to \gamma \gamma$ and ${\pi }^0{\pi }^0\eta$. New constraints for amplitude decomposition were given by the first-time result of photon beam asymmetries at $E_{\gamma }>1.84$ $\mathrm{G}\mathrm{e}\mathrm{V}$ and the most precise data of differential cross sections to date at extremely backward ${\eta }^{\mathrm{\prime }}$ angles. The possibility of a larger coupling constant of the ${\eta }^{\mathrm{\prime }}$-nucleon system to the $N(2250)$ resonance was implied in the partial wave analyses using the present data.