  We present a spectroscopic deprojection analysis of a sample of ten relaxed
galaxy clusters. We use an empirical F-test derived from a set of Markov Chain
Monte Carlo simulations to determine if the core plasma in each cluster could
contain multiple phases. We derive non-parametric baryon density and
temperature profiles, and use these to construct total gravitating mass
profiles. We compare these profiles with the standard halo parameterizations.
We find central density slopes roughly consistent with the predictions of LCDM:
$-1 \lesssim d\log(\rho)/d\log(r) \lesssim -2$. We constrain the core size of
each cluster and, using the results of cosmological simulations as a
calibrator, place an upper limit of ~0.1 cm^2/g = 0.2 b(GeV/c^2)^{-1} (99%
confidence) on the dark matter particle self-interaction cross section.
