  We report an experimental study of particle kinematics in a 3-dimensional
system of inelastic spheres fluidized by intense vibration. The motion of
particles in the interior of the medium is tracked by high speed video imaging,
yielding a spatially-resolved measurement of the velocity distribution. The
distribution is wider than a Gaussian and broadens continuously with increasing
volume fraction. The deviations from a Gaussian distribution for this
boundary-driven system are different in sign and larger in magnitude than
predictions for homogeneously driven systems. We also find correlations between
velocity components which grow with increasing volume fraction.
