  The reversible aggregates formation in a shear thickening, concentrated
colloidal suspension is investigated through speckle visibility spectroscopy, a
dynamic light scattering technique recently introduced [P.K. Dixon and D.J.
Durian, Phys. Rev. Lett. 90, 184302 (2003)]. Formation of particles aggregates
is observed in the jamming regime, and their relaxation after shear cessation
is monitored as a function of the applied shear stress. The aggregates
relaxation time increases when a larger stress is applied. Several phenomena
have been proposed to interpret this behavior: an increase of the aggregates
size and volume fraction, or a closer packing of the particles in the
aggregates.
