Dynamic coherent backscattering of ultrasound in three-dimensional strongly-scattering media
1 Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
2 Université Grenoble Alpes, LPMMC, 38000 Grenoble, France
3 CNRS, LPMMC, 38000 Grenoble, France
4 Institut Langevin, ESPCI ParisTech, CNRS UMR 7587, Université Denis Diderot - Paris 7, 1 rue Jussieu, 75005 Paris, France
a e-mail: email@example.com
Received: 24 October 2016
Revised: 13 December 2016
Published online: 25 May 2017
We present measurements of the diffusion coefficient of ultrasound in strongly scattering three-dimensional (3D) disordered media using the dynamic coherent backscattering (CBS) effect. Our experiments measure the CBS of ultrasonic waves using a transducer array placed in the far-field of a 3D slab sample of brazed aluminum beads surrounded by vacuum. We extend to 3D media the general microscopic theory of CBS that was developed initially for acoustic waves in 2D. This theory is valid in the strong scattering, but still diffuse, regime that is realized in our sample, and is evaluated in the diffuse far field limit encountered in our experiments. By comparing our theory with the experimental data, we obtain an accurate measurement of the Boltzmann diffusion coefficient of ultrasound in our sample. We find that the value of DB is quite small, 0.74 ± 0.03 mm2/μs, and comment on the implications of this slow transport for the energy velocity.
© The Author(s) 2017
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