Experimental Optimization of a Cryogenic Buffer Gas Source for Molecular Magneto-optical Traps
Molecular magneto-optical traps (MOTs) are loaded from cryogenic buffer gas beam (CBGB) sources, which produce a large flux of cold molecules. However, only a small fraction of this flux is slowed and captured. Here, we investigate and optimize one of these CBGB sources through a combination of experiment and simulation to maximize the number of molecules loaded into a MOT of CaF molecules. We experimentally determine the range of molecule velocities from the source that are successfully slowed and captured in the MOT, and perform a systematic study of buffer gas source geometries to identify designs that maximize MOT loading. Our observations agree well with Monte Carlo simulations, which provide physical insight into the dynamics within the source and explain how source geometry influences the subset of molecules that are ultimately trapped. These results provide practical design guidelines for optimizing cryogenic buffer gas beam sources used in laser cooling experiments.