Vogel-Fulcher-Tammann-type diffusive slowdown in weakly perturbed granular media.
We study the process by which a perturbed granular medium of millimetric-size particles reaches a "frozen" static configuration by decreasing perturbation intensity. The granular system is perturbed by isolated taps or by continuous vibrations. The granular process is observed by an immersed oscillator, which is used as a low-frequency "thermometer." A diffusive noise is seen until well below the fluidization limit, and the approach to the frozen configuration arises according to a modified Vogel-Fulcher-Tammann (VFT) behavior. As a function of an empirical control parameter with unit of time one recovers a standard VFT form.
D'Anna
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Institut de Génie Atomique, Département de Physique, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
Gremaud
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