A compact photon detector with nearly 4\pi -coverage in solid angle has been proposed to be implemented into the magnetic spectrometer ANKE at COSY, Jülich. Based on the physics program and experimental constraints a first concept will be presented. As part of the R\&D program, the response to monoenergetic photons between 45 and 770  MeV has been measured at the tagged photon facility at MAMI, Mainz for arrays consisting of large CeF₃ and PbWO₄ scintillation detectors. The applicability of a fine-mesh photomultiplier (Hamamatsu R5505) has been tested in static and variable magnetic fields.

PACS numbers: 29.40.Mc, 29.40.Vj