title: Internal granular dynamics, shear-induced crystallization, and compaction steps.
abstract: Internal imaging using index matching, and sensitive volume measurement, are used to investigate the spatial order and dynamics of a deep disordered layer of spheres sheared under a fixed load. Shearing triggers a crystallization transition accompanied by a step compaction event. The delay preceding the transition depends strongly on the layer thickness and can require a translation of about 10(5) particle diameters. The mean velocity varies with depth by more than five decades, and its profile is qualitatively altered by the transition.
authors.affiliation: Physics Department, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: J-C
authors.initials: JC
authors.lastname: Tsai
authors.forename: G A
authors.initials: GA
authors.lastname: Voth
authors.forename: J P
authors.initials: JP
authors.lastname: Gollub