The coordination number of granular cylinders

We report the first experimental measurements of the contact number distribution between randomly packed granular right cylinders (rods and disks) as a function of aspect ratio. The average coordination number (z) for cylinders varies smoothly with aspect ratio rising from (z) similar to 6 for aspect ratios close to one to (z) similar to 10 for large aspect ratio. Additionally, our measurements demonstrate the validity of the random contact model for compacted piles of long granular cylinders.