Experimental measurement of an effective temperature for jammed granular materials
arXiv:cond-mat/0503055 · doi:10.1073/pnas.0409911102
Abstract
A densely packed granular system is an example of an out-of-equilibrium system in the jammed state. It has been a longstanding problem to determine whether this class of systems can be described by concepts arising from equilibrium statistical mechanics, such as an ``effective temperature'' and ``compactivity''. The measurement of the effective temperature is realized in the laboratory by slowly shearing a closely-packed ensemble of spherical beads confined by an external pressure in a Couette geometry. All the probe particles considered in this study, independent of their characteristic features, equilibrate at the same temperature, given by the packing density of the system.
22 pages, 7 figures, more informations at http://www.jamlab.org