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DY: Fachverband Dynamik und Statistische Physik

DY 24: Granular matter II

DY 24.1: Vortrag

Donnerstag, 28. Februar 2008, 10:00–10:15, MA 004

Experimental study of the freely cooling granular gas — •Corinna Maaß, Nathan Isert, Christof Aegerter, and Georg Maret — Fachbereich Physik, Universität Konstanz, Universitätstrasse 10, 78457 Konstanz

In the study of granular gases, the cooling state has considerable importance as the ground state of the driven system. Theoretical studies of this state consist of Haff's cooling law for the isotropic case and modifications including inhomogeneous clustering or speed-dependent restitution coefficients. In our experiment, we diamagnetically levitate granular gases consisting of 50 -- 100 bismuth shots. The particles are excited in two different ways by either periodically changing the levitation field or by mechanical vibration with a loudspeaker. The resulting velocity distributions are recorded using video microscopy and particle tracking. With this setup we have done an experimental investigation of Haff's cooling law using a variation of Haff's law incorporating a time-dependent number density, as well as a comparative study of the small velocity range of velocity distributions for different types of heating.