MEASUREMENT OF THE OMEGA-]ETA-GAMMA DECAY-RATE

The branching ratio of the rare radiative decay omega --> eta gamma ha s been measured: BR(omega --> eta gamma) = (8.3 +/- 2.1).10(-4). The e xperiment was performed at the IHEP (Serpukhov) accelerator with 38 Ge V/c incident pions in the charge-exchange reaction pi(-)p --> omega n, the photons from the omega --> eta gamma --> 3 gamma decay being dete cted with the multiphoton spectrometer GAMS-2900. The influence of ome ga-rho mixing, which was a source of ambiguity in the interpretation o f previous experiments, has been much reduced by measuring the omega p roduced at large momentum transfer.