  We study charged particle production in proton-antiproton collisions at 300
GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with
the largest transverse momentum in each event to define three regions of
eta-phi space; toward, away, and transverse. The average number and the average
scalar pT sum of charged particles in the transverse region are sensitive to
the modeling of the underlying event. The transverse region is divided into a
MAX and MIN transverse region, which helps separate the hard component (initial
and final-state radiation) from the beam-beam remnant and multiple parton
interaction components of the scattering. The center-of-mass energy dependence
of the various components of the event are studied in detail. The data
presented here can be used to constrain and improve QCD Monte Carlo models,
resulting in more precise predictions at the LHC energies of 13 and 14 TeV.
