  Quasi-free photoproduction of $\eta '$ mesons off nucleons bound in the
deuteron has been measured with the combined Crystal Barrel - TAPS detector.
The experiment was done at a tagged photon beam of the ELSA electron
accelerator in Bonn for incident photon energies from the production threshold
up to 2.5 GeV. The $\eta '$-mesons have been detected in coincidence with
recoil protons and recoil neutrons. The quasi-free proton data are in good
agreement with the results for free protons, indicating that nuclear effects
have no significant impact. The coincidence with recoil neutrons provides the
first data for the $\gamma n \rightarrow n\eta '$ reaction. In addition, also
first estimates for coherent $\eta '$-production off the deuteron have been
obtained. In agreement with model predictions, the total cross section for this
channel is found to be very small, at most at the level of a few nb. The data
are compared to model calculations taking into account contributions from
nucleon resonances and $t$-channel exchanges.
