Production of $\eta\prime$ Mesons in the $pp \to pp\eta\prime$ Reaction   at 3.67 GeV/c
  The ratio of the total exclusive production cross sections for $\eta\prime$ and $\eta$ mesons has been measured in the $pp$ reaction at $p_{beam}=3.67$ GeV/c. The observed $\eta\prime/\eta$ ratio is $(0.83\pm{0.11}^{+0.23}_{-0.18})\times 10^{-2}$ from which the exclusive $\eta\prime$ meson production cross section is determined to be $(1.12\pm{0.15}^{+0.42}_{-0.31})\mu b$. Differential cross section distributions have been measured. Their shape is consistent with isotropic $\eta\prime$ meson production. 
Disto Collaboration: F. Balestra, Y. Bedfer, R. Bertini, L.C. Bland,   A. Brenschede, F. Brochard, M.P. Bussa, Seonho Choi, ...