We present the results of an experimental study of patterned segregation in a horizontally shaken shallow layer of a binary mixture of dry particles. An order parameter for the segregated domains is defined and the effect of the variation of the combined filling fraction, $\mathcal{C}$, of the mixture on the observed pattern formation is systematically studied. We find that there is a critical event associated with the onset of segregation, at ${\mathcal{C}}_c=0.647\pm 0.049$, which has the characteristics of a continuous phase transition, including critical slowing down.

• Received 16 July 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.244301