REACTION PI-P-]ETA' N IN THE 15-40 GEV-C MOMENTUM RANGE

Measurements were made of the cross section of the reactions π-p → ν′(958)n, η′ → 2γ at momenta at 15, 20, 25, 30 and 40 GeV/c. The experiment was carried out on the IHEP 70 GeV accelerator using the 648 channel hodoscope spectrometer NICE for γ-ray detection. A total of 6000 η′ mesons were recorded. A sharp drop is seen in the differential cross section for t → 0. The dependences of the differential cross sections for the π-p → η′n and π-p → η n on t are identical. On the basis of the ratio of the cross sections for these reactions at t = 0, i.e. R( η′ n)t=0 = 0.55 ± 0.06, the singlet-octet mixing angle for pseudoscalar mesons was determined to be β = -(18.2 ± 1.4)°. © 1979.