  The excitation function and momentum distribution of $\eta^\prime$ mesons
have been measured in photon induced reactions on $^{12}{}$C in the energy
range of 1250-2600 MeV. The experiment was performed with tagged photon beams
from the ELSA electron accelerator using the Crystal Barrel and TAPS detectors.
The data are compared to model calculations to extract information on the sign
and magnitude of the real part of the $\eta^\prime$-nucleus potential. Within
the model, the comparison indicates an attractive potential of -($37 \pm
10(stat)\pm10(syst)$) MeV depth at normal nuclear matter density. Since the
modulus of this depth is larger than the modulus of the imaginary part of the
$\eta^\prime$-nucleus potential of -($10\pm2.5$) MeV, determined by
transparency ratio measurements, a search for resolved $\eta^\prime$-bound
states appears promising.
