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Updated: Jun 30, 2025

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Cooling of a granular gas mixture in microgravity
Dmitry Puzyrev1,2,3, Torsten Trittel4,5,6,7, Kirsten Harth5,6,7
1Department of Nonlinear Phenomena, Institute of Physics, Otto von Guericke University Magdeburg, Universitätsplatz 2, 39106, Magdeburg, Germany. dmitry.puzyrev@ovgu.de.
Abstract:
Granular gases are fascinating non-equilibrium systems with interesting features such as spontaneous clustering and non-Gaussian velocity distributions. Mixtures of different components represent a much more natural composition than monodisperse ensembles but attracted comparably little attention so far. We present the observation and characterization of a mixture of rod-like particles with different sizes and masses in a drop tower experiment. Kinetic energy decay rates during granular cooling and collision rates were determined and Haff's law for homogeneous granular cooling was confirmed. Thereby, energy equipartition between the mixture components and between individual degrees of freedom is violated. Heavier particles keep a slightly higher average kinetic energy than lighter ones. Experimental results are supported by numerical simulations.
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