Fractals and dynamical chaos in a two-dimensional Lorentz gas with sinks -art. no. 036227

We consider a two-dimensional periodic reactive Lorentz gas, in which a mov ing point particle undergoes elastic collisions on fixed hard disks and ann ihilates on absorbing disks, called sinks. We present clear evidence of the existence of a fractal repeller in this open system. Moreover, we establis h a relation between the reaction rate, describing the macroscopic evolutio n of the system, and two characteristic quantities of the microscopic chaos : the average Lyapunov exponent and the Hausdorff codimension of the fracta l repeller.