Key points are not available for this paper at this time.
We studied the properties of a cold (100) and dense (10^8--10cm^-3) atomic Rydberg Cs gas, and found that the observed widths and shapes of resonances in population transfers cannot be explained in the framework of a usual gas model. We propose a ``frozen Rydberg gas'' model, where the interplay between two-body and many-body phenomena affects in an unexpected way the width and the shape of spectral lines.
Mourachko et al. (Mon,) studied this question.