DOUBLE POMERON EXCHANGE STUDIES IN P-(P)OVER-BAR INTERACTIONS AT 0.63TEV

The properties of events having the topology and kinematic features of double Pomeron exchange are described. The data were taken at the CER N ppBAR collider at square-root sBAR =0.63 TeV in the UA1 detector. A calorimeter trigger was used to isolate events in which a central clus ter of particles was separated from forward particles by large rapidit y gaps. The invariant mass M of the central cluster (possibly a collid ing Pomeron-Pomeron system) covers the range 10-70 GeV/c2. The M depen dence of charged particle multiplicity distributions in these double P omeron events is strikingly different from their square-root sBAR depe ndence in pp and ppBAR interactions.