Ultrasonic waves in strongly scattering disordered media: understanding complex systems through statistics and correlations of multiply scattered acoustic and elastic waves

Hildebrand, William Kurt

Ultrasonic waves in strongly scattering disordered media: understanding complex systems through statistics and correlations of multiply scattered acoustic and elastic waves

dc.contributor.author	Hildebrand, William Kurt
dc.contributor.examiningcommittee	Goertzen, Andrew (Physics and Astronomy) Caley, William (Mechanical Engineering) Carminati, Remi (Institut Langevin)	en_US
dc.contributor.supervisor	Page, John (Physics and Astronomy)	en_US
dc.date.accessioned	2015-09-25T13:13:12Z
dc.date.available	2015-09-25T13:13:12Z
dc.date.issued	2014-02-19	en_US
dc.degree.discipline	Physics and Astronomy	en_US
dc.degree.level	Doctor of Philosophy (Ph.D.)	en_US
dc.description.abstract	Ultrasonic wave transport in strongly scattering, disordered media is investigated via analysis of the multiply-scattered transmitted field. Measurements of transverse confinement, statistics, and correlations of the intensity were performed on an aluminum mesoglass, where aluminum beads were brazed together to form a porous slab sample. Comparison of the transverse confinement measurements with the self-consistent theory of localization was used to identify and locate a mobility edge in the sample at f = 1.1011 MHz, enabling a measurement of the critical exponent nu characterizing the Anderson transition, nu ~ 1.6–2. Infinite-range C0 correlations were observed, and observed to grow dramatically near the mobility edge, along with the C2 and C3 correlations. Measurements of the multifractal exponent Delta_2 were able to confirm the link between C0 correlations and Anderson localization. Experiments using the aluminum mesoglass with ethanol-filled pores showed evidence of two nearly-independent propagating modes, one of which appears to be characterized by a strongly renormalized diffusion coefficient. The density of states and level spacing statistics were investigated using a different mesoglass, constructed by sintering glass beads percolated on a random lattice. Direct measurements of these quantities were obtained by cutting small samples of this mesoglass, allowing individual vibrational modes to be resolved. The density of states showed a plateau extending well into the expected Debye regime, and evidence of a Boson peak was observed at low frequencies. The level spacing statistics indicated that transport in the frequency ranges measured was on the diffusive side of the mobility edge, showing agreement with the predictions of the GOE from random matrix theory. The dynamics of a suspension of bubbles were investigated using phase-based Diffusing Acoustic Wave Spectroscopy, where phase correlations were found to give additional information beyond traditional field- and intensity-based correlation measurements.	en_US
dc.description.note	October 2015	en_US
dc.identifier.citation	Hildebrand, W. K., A. Strybulevych, S. E. Skipetrov, B. A. van Tiggelen, and J. H. Page. 2014. “Observation of Infinite-Range Intensity Correlations Above, At, and below the Mobility Edges of the 3D Anderson Localization Transition.” Physical Review Letters 112(7):073902.	en_US
dc.identifier.uri	http://hdl.handle.net/1993/30843
dc.language.iso	eng	en_US
dc.publisher	American Physical Society	en_US
dc.rights	open access	en_US
dc.subject	Physics	en_US
dc.subject	Anderson localization	en_US
dc.subject	Multiple scattering of ultrasound	en_US
dc.subject	Diffusing acoustic wave spectroscopy	en_US
dc.subject	Vibrational density of states	en_US
dc.subject	Mesoscopic glasses	en_US
dc.subject	Intensity correlations	en_US
dc.subject	Disordered materials	en_US
dc.title	Ultrasonic waves in strongly scattering disordered media: understanding complex systems through statistics and correlations of multiply scattered acoustic and elastic waves	en_US
dc.type	doctoral thesis	en_US