Observation of $e^{+}{e}^{-}\to {\eta }^{\mathrm{\prime }}J\mathrm{/}\psi$ at center-of-mass energies between 4.189 and 4.600 GeV

The process $e^{+}{e}^{-}\to {\eta }^{\mathrm{\prime }}J\mathrm{/}\psi$ is observed for the first time with a statistical significance of $8.6\sigma$ at center-of-mass energy $\sqrt{s}=4.226$ GeV and $7.3\sigma$ at $\sqrt{s}=4.258$ GeV using data samples collected with the BESIII detector. The Born cross sections are measured to be $(3.7\pm 0.7\pm 0.3)$ and $(3.9\pm 0.8\pm 0.3)$ pb at $\sqrt{s}=4.226$ and $4.258$ GeV, respectively, where the first errors are statistical and the second systematic. Upper limits at the 90% confidence level of the Born cross sections are also reported at other 12 energy points.