  We study the measurement of transverse diffusion through beam echoes. We
revisit earlier observations of echoes in RHIC and apply an updated theoretical
model to these measurements. We consider three possible models for the
diffusion coefficient and show that only one is consistent with measured echo
amplitudes and pulse widths. This model allows us to parameterize the diffusion
coefficients as functions of bunch charge. We demonstrate that echoes can be
used to measure diffusion much quicker than present methods and could be useful
to a variety of hadron synchrotrons.
