The unexpected nodal structure of the beam asymmetry recently re-
ported by the GRAAL collaboration in η' photoproduction very close
to threshold could be explained by a previously unobserved very nar-
row resonance. Therefor, the measurement is important to be inde-
This possibility is offered by the BGO-OD experiment. It is well suited
for the detection of forward going charged particles which in the thresh-
old region of interest allows the identification of the reaction γp → η'p
solely based on the proton going in forward direction. This yields un-
precedented statistics if in the missing mass analysis of the η' meson
the background can be sufficiently well controlled. A linearly polarized
photon beam produced via coherent bremsstrahlung off a diamond ra-
diator makes it possible to measure the η' beam asymmetry.
In this talk I will present preliminary results on the determination of
the η' beam asymmetry in several energy and angular bins close to
Supported by DFG (PN 50165297).