Speaker
W.J. Llope
(Rice University)
Description
In the dense and high-temperature systems formed in relativistic
heavy-ion collisions, final-state composites - light nuclei and
antinuclei - are formed close to the freeze-out hypersurface. Their
spectra, compared to those of the constituent (anti)nucleons, can be
described by picturing the formation process as the coalescence of a
number of nucleons that are close to each other in phase space. This
makes the composite spectra sensitive to the distribution of the
constituent nucleons in phase space. It also implies a sensitivity of
the spectra to the local densities and flow velocities of the source.
In the coalescence picture, specific ratios of these spectra provide
information on the baryon densities and homogeneity volumes. The
STAR experiment has collected data from Au$+$Au collisions at
seven beam energies, $\sqrt{\rm s_{\rm NN}}$, ranging from 7.7
to 200 GeV. The particle identification is performed for transverse
momenta from $\sim$0.3 to
\raisebox{-0.6ex}{$\stackrel{>}{\sim}$}3 GeV/c using a
combination of the ionization energy loss in the Time Projection
Chamber and the time of flight. The spectra for (anti)protons,
(anti)deuterons, and (anti)tritons at mid-rapidity, and the source
information inferred from these spectra, will be presented and
compared to several dynamic coalescence models.
Primary author
W.J. Llope
(Rice University)