  We present an experiment in which a horizontal quasi-2D granular system with
a fixed neighbor network is cyclically compressed and decompressed over 1000
cycles. We remove basal friction by floating the particles on a thin air
cushion, so that particles only interact in-plane. As expected for a granular
system, the applied load is not distributed uniformly, but is instead
concentrated in force chains which form a network throughout the system. To
visualize the structure of these networks, we use particles made from
photoelastic material. The experimental setup and a new data-processing
pipeline allow us to map out the evolution subject to the cyclic compressions.
We characterize several statistical properties of the packing, including the
probability density function of the contact force, and compare them with
theoretical and numerical predictions from the force network ensemble theory.
