  We present core radii for 54 Milky Way globular clusters determined by
fitting King-Michie models to cumulative projected star count distributions. We
find that fitting star counts rather than surface brightness profiles produces
results that differ significantly due to the presence of mass segregation. The
sample in each cluster is further broken down into various mass groups, each of
which is fit independently, allowing us to determine how the concentration of
each cluster varies with mass. The majority of the clusters in our sample show
general agreement with the standard picture that more massive stars will be
more centrally concentrated. We find that core radius vs. stellar mass can be
fit with a two parameter power-law. The slope of this power-law is a value that
describes the amount of mass segregation present in the cluster, and is
measured independently of our distance from the cluster. This value correlates
strongly with the core relaxation time and physical size of each cluster.
Supplementary figures are also included showing the best fits and likelihood
contours of fit parameters for all 54 clusters.
