  We report direct, time-resolved observations of single-photon superradiance
in a highly extended, elliptical sample of cold 87Rb atoms. The observed rapid
decay rate is accompanied by its counterpart, the cooperative Lamb shift. The
rate of the strongly directional decay, and the associated shift, scale
linearly with the number of atoms and show a strong dependence on the sample
shape, demonstrating the collective nature of the observed quantities.
