  The triple-Pomeron coupling lies at the heart of the predictions for high
energy diffractive processes. We explain why the existing determinations, which
use single-particle inclusive hadronic data a+b -> a+Y, underestimate the value
of the bare coupling, due to the neglect of soft rescattering which populates
the rapidity gaps. We describe how data for the process gamma+p -> J/psi +Y can
be used to give a much more reliable estimate of the bare coupling. We use the
existing, fragmentary, J/psi data from HERA to show that the triple-Pomeron
coupling is probably about 3 times larger than the previous determinations. We
emphasize the importance of an explicit measurement of the mass spectrum of the
Y system which accompanies J/psi production at HERA. The consequences for ultra
high energy cosmic ray showers are mentioned.
