We present experimental results on the velocity statistics of a uniformly
heated granular fluid, in a quasi-2D configuration. We find the base state, as
measured by the single particle velocity distribution f(c), to be universal
over a wide range of filling fractions and only weakly dependent on all other
system parameters. There is a consistent overpopulation in the distribution's
tails, which scale as fâexp(const.Ăcâ3/2). More
importantly, the high probability central region of f(c), at low velocities,
deviates from a Maxwell-Boltzmann by a second order Sonine polynomial with a
single adjustable parameter, in agreement with recent theoretical analysis of
inelastic hard spheres driven by a stochastic thermostat. To our knowledge,
this is the first time that Sonine deviations have been measured in an
experimental system.Comment: 13 pages, 15 figures, with minor corrections, submitted to Phys. Rev.