  Understanding propagation of scintillation light is critical for maximizing
the discovery potential of next-generation liquid xenon detectors that use
dual-phase time projection chamber technology. This work describes a detailed
optical simulation of the DARWIN detector implemented using Chroma, a GPU-based
photon tracking framework. To evaluate the framework and to explore ways of
maximizing efficiency and minimizing the time of light collection, we simulate
several variations of the conventional detector design. Results of these
selected studies are presented. More generally, we conclude that the approach
used in this work allows one to investigate alternative designs faster and in
more detail than using conventional Geant4 optical simulations, making it an
attractive tool to guide the development of the ultimate liquid xenon
observatory.
