We study the aging of a colloidal laponite glass by measuring the dynamic structure factor of dilute embedded tracer particles on micrometric length scales. We show that an initial aging regime, where the decay time grows exponentially with aging time $t_w$, $\tau \sim \exp \left(\gamma t_w\right)$, is followed by a full aging regime, $\tau \sim t_w^v$ with $v\approx 1$. The dynamics of the tracers is diffusive in the exponential regime and hyperdiffusive in the full aging regime, up to micrometric length scales.

• Received 3 December 2004

DOI:https://doi.org/10.1103/PhysRevE.72.011403