Scaling laws for large magneto-optical traps

Multiple scattering of light has been the main limitation of the maximum atomic density achievable in magneto-optical traps (MOTs). We present a detailed experimental investigation of the size and density scaling laws for large MOTs with up to N = 10(10) atoms, larger than those usually studied in detail. Most of our observations can be explained with previous models and only a few regimes show unexplained deviations. We also propose a new repulsion mechanism, based on the rescattered repumper photons that might limit the atomic density of atoms when the optical thickness for repumper light becomes important, adding an additional ingredient in the complexity of large MOTs.