We describe a navel technique for comparing total cross sections for the re
actions pp --> pp pi(0), pp --> pp eta, and pp --> pp eta' close to thresho
ld. The initial and final state proton-proton interactions rue factored out
of the total cross section, and the dependence of this reduced cross secti
on on the volume of phase space is discussed. Different models of the proto
n-proton interaction are compared. We argue that the scattering length of t
he S-wave eta'-proton interaction is of the order of 0.1 fm. (C) 2000 Elsev
ier Science B.V. All rights reserved.