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

The properties of events having the topology and kinematic features of double Pomeron exchange are described. The data were taken at the CERN 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 cluster of particles was separated from forward particles by large rapidity gaps. The invariant mass M of the central cluster (possibly a colliding Pomeron-Pomeron system) covers the range 10-70 GeV/c2. The M dependence of charged particle multiplicity distributions in these double Pomeron events is strikingly different from their square-root sBAR dependence in pp and ppBAR interactions.