Beam energy dependence of d and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mover accent="true"><mml:mrow><mml:mi>d</mml:mi></mml:mrow><mml:mo>‾</mml:mo></mml:mover></mml:math>production in Au+Au collisions at RHIC

The binding energy of light nuclei is small compared to the temperature of the system created in heavy-ion collisions. Consequently, the yields 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 sNN=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 B2 for deuteron and anti-deuteron production are discussed. We find the values of B2 for anti-deuterons 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 B2 are found to vary with collision energy and show a broad minimum around sNN=20GeV, implying a change of the equation of state of the medium in these collisions.