Program: GS-2018B-Q-226

Galactic globular cluster are crucial laboratories and benchmarks for our understanding of the nearby and distant universe. We will use the GeMS/GSAOI instrument to obtain deep J and Ks photometry of 9 Milky Way globular clusters that were previously observed by the HST/ACS Galactic Globular Cluster Survey and the HST UV Legacy Survey of Galactic Globular Clusters in the UV and optical filters and that are accessible to GSAOI in period 2018B. With these data we will i) study the morphology of near-IR CMDs and determine the internal consistency of model CMD predictions for various J and Ks filter combinations and test the influence of molecular absorption band variations on theoretical isochrone predictions in the near-IR using abundance measurements from high-resolution spectroscopy, ii) derive absolute GC ages to better than a Gyr and corresponding metallicities with uncertainties Delta(Z)~0.1 dex, iii) explore how age and stellar content may affect horizontal-branch morphology, and iv) characterize the population of binary stars.