Light nuclei production in heavy-ion collisions at relativistic energies

We have measured the production of light nuclei $(A<~3)$ in $11.6 \mathrm{GeV}/c$ Au-Au collisions at the Brookhaven Alternating Gradient Synchrotron (AGS). The transverse mass spectra are analyzed using a thermal fireball model, and the yields for different particle species are discussed assuming coalescence and fragmentation as possible production mechanisms. The wide acceptance range of the ${}^{3}\mathrm{He}$ measurements permits a broad study of the coalescence parameter ${B}_{3}$ as functions of transverse momentum and rapidity. Comparisons with data obtained previously at AGS energies suggest that the simple models are insufficient to describe fully the production mechanisms of light nuclei.