Diffuse light scattering from a dense and cold microscopic $^{87}$Rb sample

We report investigation of near-resonance light scattering from a cold atomic sample of $^{87}$Rb. Measurements are made on the $F=2\to F'=3$ nearly closed hyperfine transition for atomic densities ranging from $\sim10^{10}$ to $\sim10^{13}$ atoms/cm$^3$. The sample, initially prepared in a magneto-optical trap, is loaded into a far-off-resonance trap (FORT) in which the ensemble has a temperature $\sim$100 $\mu$K and initial Gaussian radii of $\sim$3 $\mu$m and $\sim$280 $\mu$m in the transverse and longitudinal directions, respectively. The experimental geometry consists of projecting a near-resonance collimated laser beam onto the entire volume of the FORT and detecting the diffusely scattered light. The measured scattered light intensity as a function of detuning, atomic density, and sample size suggests that collective light scattering plays an important role in the experimental results.