  Light nuclei have much smaller binding energy compared to the temperature of
the system created in heavy-ion collisions. Consequently, the distributions of
light nuclei can be used to probe the freeze-out properties, such as
correlation volume and local baryon density of the medium created in
high-energy nuclear collisions. In this paper, we report the results of
deuteron and anti-deuteron production in Au+Au collision at
$\sqrt{s_\mathrm{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV,
measured by STAR at RHIC. The collision energy, centrality and transverse
momentum dependence of the coalescence parameter $B_2$ for deuteron and
anti-deuteron production are discussed. We find the values of $B_2$ for
anti-deuteron are systematically lower than those for deuterons indicating the
correlation volume of anti-baryon are larger than that of baryon. In addition,
the values of $B_2$ are found to decrease with increasing collision energy and
reach a minimum around $\sqrt{s_\mathrm{NN}}$ = 20 GeV implying a change of the
equation of state of the medium in these collisions.
