title: Velocity fluctuations in a homogeneous 2D granular gas in steady state
abstract: We have measured the spectrum of velocity fluctuations in a granular system confined to a vertical plane and driven into a homogeneous, steady state by strong vertical vibration. The distribution of horizontal velocities is not Maxwell-Boltzmann and is given by P(v) = Cexp[-beta(|v|/sigma)(alpha)] where alpha = 1.55+/-0.1 at all frequencies and amplitudes investigated, and also for varying boundary conditions. The deviation from Maxwell-Boltzmann statistics occurs in the absence of spatial clustering and does not result from an inhomogeneous average over regions of varying local density. Surprisingly, P(v) has the same shape over a wide range of densities.
authors.affiliation: Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-3720, USA.
authors.initials: F
authors.lastname: Rouyer
authors.initials: N
authors.lastname: Menon