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Experimental measurement of an effective temperature for jammed granular materials

Chaoming Song·Ping Wang·Hernan A. Makse
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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.

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Chaoming Song, Ping Wang, Hernan A. Makse. 2005-03-02. Experimental measurement of an effective temperature for jammed granular materials. https://doi.org/10.1073/pnas.0409911102

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