  We report an experimental study of a dilute "gas" of inelastically colliding
particles excited by vibrations in low gravity. We show that recording the
collision frequency together with the impulses on a wall of the container gives
access to several quantities of interest. We observe that the mean collision
frequency does not scale linearly with the number N of particles in the
container. This is due to the dissipative nature of the collisions and is also
directly related to the non extensive behaviour of the kinetic energy (the
granular temperature is not intensive).
