This the manuscript of the two-pion interferometry from the beam energy scan.  It is probably best known for the azimuthal HBT analysis.  This is the thesis work of Chris Anson.

The abstract:
We present results of analyses of two-pion interferometry in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5,
19.6, 27, 39, 62.4 and 200 GeV measured in the STAR detector as part of the RHIC Beam Energy
Scan program. The extracted correlation lengths (HBT radii) are studied as a function of
beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass ($m_T$)
of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at
kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes
in the equation of state.  A new global fit method is studied as an alternate method to directly
measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease
with beam energy that is qualitatively consistent with the trend from all model predictions and
quantitatively consistent with a hadronic transport model.

Chris' protected web page (with STAR Note etc) for this manuscript may be found here:  www.star.bnl.gov/protected/bulkcorr/canson/Paper/LongPaper/