Investigation of the decay η′ → 3 π0 with the GAMS-4π spectrometer

An experiment performed with the GAMS-4π spectrometer resulted in observing 235 ± 45 events of the decay η′ → 3π 0. The respective charge-exchange reaction at a momentum of 32.5 GeV/c was used as a source of η′ mesons. The decay branching ratio was found to be Br(η′ → 3π 0) = (1.8 ± 0.4) × 10−3. The slope parameter of the square of the respective matrix element in the linear approximation proved to be β = −0.59 ± 0.18.