  The problem of Maxwell's demon in granular gas is revisited in the case of a
mixture of two particle species. The phase space is found to be 2d. Existence
of cyclic orbits, with periodic segregation, is demonstrated by investigating
the case of 2 kinds of particles with identical parameters but different
masses. At large excitation equi-partition shall be obtained, but convergence
towards the steady state is found in spiral. The spiral convergence is imposed
due to the rule of kinetic-energy transfer between the two species. It results
that the most probable scenario is that the steady state breaks into cyclic
orbit at lower amplitude of vibration below a bifurcation threshold. The nature
of the bifurcation is not known; it can be critical, subcritical, hypercritical
or can exhibit a tri-critical point as varying the control parameters. No
conclusion is obtained at very low vibration amplitude: it is guessed two
scenarii under further cooling which generates Maxwell's demon and
segregation..
